食品包装技术（英文版）：36756_22

22.1 Introduction Major technological developments in food packaging can introduce many benefits to consumers and food and food-packaging industries, but at the same time they are liable to the introduction of new problems. Although active and intelligent packaging continues to broaden in scope and these new packaging systems are already being successfully applied in the USA, Japan and Australia, its penetration in the European marketplace has been quite limited thus far. This is partly due to the strict European regulations for food contact materials, which fail to keep up with technological innovations and currently prohibit the application of many of these systems. In addition, a lack of knowledge of consumer acceptance, of economic aspects and of the environmental impact of these novel concepts and, in particular, the lack of hard evidence of their effectiveness demonstrated by independent investigators has inhibited their commercial usage. Within the Actipak project active and intelligent packaging systems were defined as follows: 1 ? Active packaging actively changes the condition of the packaged food to extend shelf-life or improve food safety or sensory properties while maintaining the quality of the packaged food. ? Intelligent packaging systems monitor the condition of packaged foods to give information about the quality of the packaged food during transport and storage. In Europe, no specific regulation governing active and intelligent food packaging exists to date. Most active and intelligent agents are not considered 22 Legislative issues relating to active and intelligent packaging N. de Kruijf and R. Rijk, TNO Nutrition and Food Research, The Netherlands as food additives but rather as food contact material constituents, and therefore these food packaging systems should comply with the existing regulations for food contact materials. When these regulations were drafted, no allowance was made for active and intelligent packaging as these systems were not applied as food contact materials in Europe at that time. The current packaging regulations require that all components used for the manufacture of food contact materials are covered by so-called positive lists. These lists of approved compounds usually include components required to manufacture the packaging material. Constituents used for other purposes such as extending or monitoring the shelf- life of packaged foods are not included. Therefore, most active and intelligent agents are not listed. In addition, active and intelligent systems should comply with relevant overall and specific migration limits. The overall migration limit of 60 mg per kg food is a major hurdle to the application of active packaging in Europe, especially when the system is designed to release active ingredients into foods to extend their shelf-life or improve their quality. Moreover, current migration tests are not always suitable for these new packaging systems because the conventional ratio of 6 dm 2 to 1 kg food is generally much smaller and, in addition, they often differ in contact mode from conventional packaging. Therefore, a new approach to food packaging regulations is required, and new migration test methods should be developed and validated for some of these new food packaging systems. No single European regulation currently covers specifically the use of active and intelligent packaging systems. The food-contact application of active and intelligent packaging systems is covered by a range of EU regulations, each having its specific requirements, such as regulations for food-contact materials, food additives, biocides, modified-atmosphere packaging, hygiene of foodstuffs, labelling and packaging waste. Some of these regulations may be, unintentionally, an obstacle to the introduction of active and intelligent systems in Europe. Therefore, a few years ago, two initiatives were taken to implement active and intelligent packaging within the European regulations. In 1999, a pan-European project was started within the framework of the EU FAIR R&D programme. The study aims at initiating amendments to European legislation for food contact materials to establish and implement active and intelligent systems within the current relevant regulations for packaged food in Europe. 1, 2 In 2000, a comprehensive report on legislative aspects of active and intelligent food packaging was published by a project group under the Nordic Council of Ministers. The report describes some types of active and intelligent food contact materials, the legislation the project group found to be relevant to consider, as well as some conclusions and proposals for administrators for future work with recommendations and interpretations of existing legislation. Also, the possibility of establishing new specific legislation for active and intelligent packaging is considered. 3 Both initiatives will now be discussed in more detail below. 460 Novel food packaging techniques 22.2 Initiatives to amend EU legislation: European project In 1999, a European study was started to enable the safe application of active and intelligent packaging systems throughout Europe by initiating amendments to European legislation for food contact materials in order to establish and implement these systems in current relevant regulations for packaged food in Europe. The study was entitled ‘Evaluating safety, effectiveness, economic- environmental impact and consumer acceptance of active and intelligent packagings’ (‘Actipak’). The Actipak project was co-ordinated by TNO Nutrition and Food Research and was jointly carried out by nine research organizations and three industrial companies. 1 The research project consisted of five key tasks. The study was completed by the end of 2001. For each task the main results and conclusions are summarized below. Task 1: Inventory At the start of the project an overview of all existing commercial and promising but not (yet) commercially available active and intelligent packaging systems was prepared. The review contains information on technology, market trends, consumer needs and current legislation in Europe and relevant countries outside Europe. Part of the review has been described in detail in a separate publication. 2 The main conclusion to be drawn from the review is that no European regulation currently covers the use of active and intelligent packaging. The traditional European regulations for food contact materials, the overall migration limit and lists of approved compounds may be inconsistent with some of the objectives of active and intelligent packaging. In addition, some 25 packaging systems were selected for compositional analysis and overall migration study (Task 2). Task 2: Classification of active and intelligent systems In this task the composition and migration behaviour of selected active and intelligent packaging systems were investigated to identify conflicts with current legislation. A total of 20 active systems and 6 intelligent systems were investigated. The composition was investigated in view of the EU positive list and positive lists of national regulations. Determination of the composition focused on active ingredients and relevant reaction products. The compositional analysis of some active packaging systems has been described in detail. 4, 5 Some typical results are shown in Table 22.1. 1 The compositional analysis revealed that many active and intelligent packaging systems are very complex in composition. Apart from plastics, other materials such as paper, metals, adhesives, printing and minerals are being used. Existing EU legislation for food contact materials such as the EU Directive for polymeric food contact materials (Directive 90/128/EEC and its amendments) applies to only a minority of the materials tested. In addition, the overall migration behaviour of the active and intelligent packaging systems was investigated. Some relevant results of the overall migration study obtained for oxygen scavengers and moisture absorbers Legislative issues relating to active and intelligent packaging 461 are presented in Table 22.2. 1 A complete overview of all migration values obtained in this study has been reported by De Meulenaer et al. 5 Quite a few migration values obtained exceed the overall migration limit. Some of the high levels observed were supposed to be attributable to the use of inappropriate liquid migration simulants. Solid migration simulants such as agar gels could be an alternative. 6 The three time-temperature indicators were not included in the overall migration study. As the current systems are generally applied on the outside of the packaging and for relatively short periods of time, the packaging material can be considered to be a functional barrier, and therefore migration testing of time- temperature indicators is not relevant. Based on the results of the evaluation of the composition and the migration behaviour, the active and intelligent systems were classified in view of restrictions of current regulations into five categories (A–E) according to the scheme shown in Fig. 22.1. These categories are: Category A: Systems that comply with the current legislation (i.e. composition and migration). Category B: A system belongs to category B if it contains components not listed in the positive lists of the EC (90/128/EEC and amendments) but which are food additives and/or natural components and/or other components of which toxicological data are available. The migration behaviour of the category-B systems is in compliance with the migration limits as set by the EC. Table 22.1 Composition of some active and intelligent packaging systems 1 Packaging system Ingredients identified Oxygen scavengers Iron powder Silicates Sulfite Chloride Polymeric scavenger Elements: Fe, Si, Ca, Al, Na, Cl, K, Mg, S, Mn, Ti, Co, V, Cr, P Antimicrobial releasers Acids Silicates Ethanol Zinc Elements: Si, Na, Al, S, Cl, Ca, Mg, Fe, Pd, Ti Methylene blue and other colour indicators Indicators Acids Antioxidants Mineral oil Sugars Elements: Na, Ca, K, Si, Al, Mg 462 Novel food packaging techniques Table 22.2 Overall migration from oxygen scavengers and moisture absorbers 1 Overall migration (mg/sample) into: Sample Type Test Water 3% 10% 15% 95% Iso- Olive condition Acetic Ethanol Ethanol Ethanol octane oil acid Oxygen scavenger Sachet 10 days at 40oC 620 b 1700 c – 800 a 210 c – 2 days at 20oC 1.9 c Oxygen scavenger Cap 10 days at 40oC 74 c 98 c 80 c – 43 c – 2 days at 20C 0.9 c Oxygen scavenger Crown 30 min. at 70oC 1.0 c 1.7 c 1.5 a – – – 27.8 a + 10 days at 40oC Moisture absorber Sachet 10 days at 40oC <0.1 a 970 c – 0.6 c 2.3 c 2 days at 20oC <0.1 a – Moisture absorber Pad 10 days at 40oC 9.3 b 46 c – 7.2 b 21 c – 2 days at 20oC 18 c Moisture absorber d Film 10 days at 40oC 260 a 300 a – 300 b 8.2 b – 2 days at 20oC 0.1 c a Standard deviation <5% (n = 3 or 4) b Standard deviation >5% and <10% (n = 3 or 4) c Standard deviation > 10% (n = 3 or 4) d Overall migration in mg/dm 2 instead of mg/sample – Not measured Category C: These systems contain components that are included in the positive lists of the EC, but the migration exceeds the migration limit(s) set in the current legislation. Category D: These systems contain components that are not included in the positive lists of the EC but are food additives or natural components or other components for which toxicological data are Fig. 22.1 Classification of active and intelligent food-packaging systems in view of current legislation. For a description of categories A–E, see the text (reproduced with permission from Food Additives and Contaminants, July 2002. http:/www.tandf.co.uk). 464 Novel food packaging techniques available. In addition, the migration from the systems exceeds the migration limit(s) set by the EC. Category E: These systems contain components that neither are listed nor are food additives or natural components or other components for which no toxicological data are available. Most of the systems investigated could be classified into categories A and B. Some fall into categories C and D. Only a carbon dioxide-releasing system could not be classified. 5 Generally, it could be concluded that an extension of existing regulations with dedicated requirements seems to be necessary to permit the breakthrough of these materials on the EU market and to guarantee their safe introduction and use in Europe. The results of the classification have been used to select representative combinations of foods and active and intelligent packaging systems for further validation studies. An overview of the food-packaging combinations selected for evaluation of microbiological safety, shelf-life-extending capacity and efficacy of the active and intelligent systems is presented in Table 22.3. Task 3: Evaluation of microbiological safety, shelf-life-extending capacity and efficacy of active and intelligent systems In this task an overall evaluation of the capability (including effectiveness, safety and shelf-life-extending capacity) of the active and intelligent packaging systems was conducted. To this end, the microbiological safety of the test food, packed and stored in active packaging systems, was determined by analyzing their microbiological condition. In addition, the risk of false indication of intelligent systems was examined. Furthermore, the effectiveness of active Table 22.3 Food-packaging combinations selected for validation studies Packaging system Food Oxygen-scavenging film Fresh pasta Moisture-absorbing film Fish Moisture-absorbing pad Fresh meat Ethylene-absorbing film Bananas Antimicrobial film Cheese Antimicrobial film Meat Antimicrobial film Fruit Aldehyde-absorbing film Cereal Oxygen-scavenging sachet Milk powder Oxygen-scavenging sachet Biscuits Moisture-absorbing sachet Milk powder Antimicrobial sachet Sandwich bread Oxygen-scavenging crown Beer Time-temperature indicators Fish Oxygen indicators Sliced meat Carbon dioxide indicator Sliced meat Legislative issues relating to active and intelligent packaging 465 packaging systems to improve the microbiological stability of food, as compared to traditional packaging systems, was tested. Also the extension of sensory and chemical shelf-life was investigated for different active packaging/food combinations. In total, 12 studies were performed to investigate the effectiveness and shelf-life-extending capacity of selected food/active packaging combinations. Some typical results are presented in Table 22.4. Most of the active systems investigated appeared to be effective as claimed by their manufacturers. From the shelf-life studies it can be concluded that a number of active systems indeed prolong shelf-life. The indication capacity of three time-temperature indicators, two oxygen indicators and a carbon dioxide indicator was investigated. The indicators investigated indicated relatively well the conditions they were meant for (time-temperature history, package headspace oxygen or carbon dioxide). Task 4: Toxicological, economic and environmental evaluation of active and intelligent systems Intelligent devices and some active systems may contain substances that are not food additives and have not been evaluated by the EU Scientific Committee on Food (SCF) for use in food contact materials. Within the Actipak project it was therefore agreed to study the consequences when a substance is not on the positive list of the directives on food contact materials and to collect and interpret available toxicological data. Examination of existing toxicity data of Table 22.4 Effectiveness and shelf-life extending capacity of some food/active packaging test combinations Active packaging Food product Effective Shelf-life extension * Oxygen-scavenging film Fresh pasta Yes Yes, longer microbiological shelf-life not due to O 2 absorption but to barrier characteristics of the active film Moisture-absorbing pad Pork Yes No, same microbiological and sensory shelf-life Antimicrobial film Cheese/ bread Possibly No, same microbiological shelf-life Aldehyde-absorbing film Cereals Yes Yes, longer sensory and chemical shelf- life O 2 -absorbing sachet Milk powder Yes No, but a good alternative (same sensory and chemical shelf-life) to MAP can packaging O 2 -absorbing sachet Cooked ham Yes Yes, longer sensory shelf-life/same microbiological shelf-life O 2 -absorbing crown cork Beer Yes No, same sensorial shelf-life * Compared with a food/packaging combination without an active packaging system. 466 Novel food packaging techniques one substance with oxygen absorption capacity indicated the substance to be potentially mutagenic. This demonstrates that substances used in active and intelligent packaging systems should be evaluated by SCF before allowing them to come in contact with foodstuffs. In other words, they should be evaluated like all other substances used in food contact materials. To establish acceptance among European consumers of active and intelligent systems that have been proved to be suitable and safe, these systems were subjected to an international study on consumers’ attitudes towards application of these systems. This study also provides insights into national differences and general attitudes. Consumer focus groups consisting of 8–12 people of mixed age and sex were formed in six European countries, namely the UK, Italy, Germany, the Netherlands, Finland and Spain. The results demonstrated that for active and intelligent devices to be readily accepted in Europe in the immediate future, their introduction to the marketplace should be supported by a substantial information campaign clarifying their benefits and how they function. They will not gain acceptance purely by virtue of extension of shelf-life. Also, to avoid confusion, some standardization, at least of indicators, would be preferable. Attitudes are fairly consistent in Europe with the exception of Spain and possibly Italy. Consumers in Spain were much more ready to accept both active devices (absorbers, including sachets) and indicators, and responded very positively to them. Italy also seemed slightly keener than the rest of Europe. The economic consequences and environmental implications of active and intelligent systems were evaluated as part of the project. The shelf-life- extending capacity of active packaging is expected to reduce food waste due to spoilage. Consequently, energy and packaging materials may be saved. Multi- layer barrier packaging materials might be replaced by less complicated packaging materials, thus reducing packaging waste. In addition, from the study the conclusion can be drawn that the use of intelligent packaging such as time- temperature indicators will decrease the waste generated in the long term. Task 5: Recommendations for legislative amendments Finally, all results of the project and the requirements of all relevant EU regulations were evaluated. Based on this evaluation recommendations were drafted for the implementation of suitable active and intelligent systems in relevant European Directives. These recommendations were discussed informally with several national and European authorities. In addition to food packaging regulations, other relevant European regulations were studied such as regulations for food additives, biocides, pesticides, modified-atmosphere packaging, flavouring, food hygiene, labelling, product safety and packaging waste. These regulations generally do not form a serious hurdle to the safe introduction of active and intelligent food packaging systems in Europe. The directive on food hygiene even appeared to be an incentive to the use of active and intelligent packaging. The first proposal for changing the framework Directive 89/109/EEC has resulted in a draft amendment of the this directive in which active packaging is Legislative issues relating to active and intelligent packaging 467 included in the scope as described in Article 1. It is expected that this amendment will be approved by the end of 2003. This will remove the first barrier to the introduction of active packaging systems in Europe. A more detailed description of the results of this task will be given in section 22.4. 22.3 Initiatives to amend EU legislation: Nordic report The Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) have a long tradition of co-operation in the food packaging area, and these countries have similar legislation for food contact materials. A project group under the Nordic Council of Ministers has discussed the legal aspects of active and intelligent systems. The project group was chaired by Dr Fabech of the Danish Veterinary and Food Administration. In 2000, the project group published a report on legislative aspects of active and intelligent food packaging. 3 This so- called ‘Nordic Report’ aimed at contributing to a solution of legislative problems related to active and intelligent food contact materials. In the first chapter of that report an overview is given of different types of active and intelligent food packaging. The effectiveness of these systems and the test requirements are discussed. The most important part of the report is a comprehensive overview of European legislation relevant to active and intelligent packaging. In section 22.4, a description of these EU directives is given and their relevance to active and intelligent packaging is discussed. In the Nordic report recommendations are also given as to which parts of the EU legislation should be reviewed and which questions could be solved through interpretation of existing legislation. Preferably, harmonized legislation should be interpreted on a European basis to avoid divergence in interpretation, which could lead to barriers to trade. Proposals are given for solutions to problems by interpretation. According to the Nordic group, it is not necessary to introduce new EU legislation. Instead, amendments should be made to existing legislation and guidelines on how to interpret existing legislation should be given. Finally, initiatives are proposed to be taken by legislators, both on a national and on an EU level, when drafting new or revising existing legislation on active and intelligent packaging. 22.4 Current EU legislation and recommendations for change For this study of relevant European regulations, a schedule was made of the scope of active and intelligent packaging systems. Definitions of active and intelligent systems are proposed. Based on that principle an overview of the physical appearance of the systems is required as well as a division by functionality of the various systems. 468 Novel food packaging techniques 22.4.1 Scope of active and intelligent systems Active systems Active packaging systems may differ in appearance. Active packaging systems may be packaging materials to wrap foodstuffs, but may also be added to the packed food in the form of a sachet, label, box, etc. A correct description, which will be used in regulatory amendments, would be ‘active food contact material systems’. For practical reasons, the term ‘active packaging systems’ will be used here. Conventional packaging materials are considered passive, and their main function is protection against the environment. Active packaging systems intentionally absorb or release substances from or to the food or its environment. Ingredients required to achieve the effect may be incorporated in the packaging material itself or packed in a sachet or label inserted into the package. The total contact area of active packaging systems may be the same as for conventional packaging material, such as a film. But, in case of sachets or labels, the ratio may be significantly smaller than 6 dm 2 /kg food. This may influence migration requirements and testing protocols. Both absorption and release of substances should not endanger human health. For this purpose many regulations at the EU and the national level are in force, which should be taken into account to judge the acceptability of an active packaging system. Intelligent systems Intelligent systems are only occasionally packaging materials. They usually are packed together, inside or outside the primary packaging, with the food in the form of a label, a pill, etc. As there is potential contact with food they should be called ‘intelligent food contact material systems’ but, for practical reasons they will be called ‘intelligent packaging systems’ here. Intelligent packaging systems provide the user with information on the conditions of the food. Intelligent systems do not influence the food but provide information to consumers, retailers, manufacturers, etc. Intelligent packaging systems should not release their constituents to the food. In many cases a so- called functional barrier, which prevents migration, is present. However, attention must be paid to the fact that intelligent systems may contain all kinds of chemicals required for detection of the intended information. Attention should also be paid to the acceptance of the use of these substances, particularly for packed foods presented directly to the consumer. Starting from the requirement that safety of the food and subsequently safety of the consumer shall never be endangered, the legal restrictions as well as the possibilities for the use of active and intelligent systems were studied in depth. Solutions for existing barriers are proposed. 22.4.2 Identification of relevant regulations Active and intelligent packaging systems in contact with foods should comply with regulations on food contact materials. In addition, the composition of the Legislative issues relating to active and intelligent packaging 469 food can be influenced by the use of active packaging systems. The following regulations are considered and further discussed: ? food contact materials ? food additives ? flavouring ? hygiene ? biocides ? pesticides ? labelling ? product safety ? weight and volume ? waste. 22.5 Food contact materials The requirements for food contact materials (FCM) are formulated in general terms in Framework Directive 89/109/EEC; 7 some materials are regulated in detail in specific directives. Directive 89/109/EEC is under revision and will be published in 2003. 22.5.1 Framework Directive 89/109/EEC Directive 89/109/EEC specifies the definition of FCM and general requirements. Article 2 requires production of FCM according to good manufacturing practice, while application of FCM shall not endanger human health or change the composition or sensory properties in an unacceptable way. Article 6 describes the requirements for labelling and a demonstration of compliance with specific directives. Relevance to active and intelligent packaging systems Undoubtedly, active and intelligent packaging systems are intended to come into contact with food, although some may be separated by a ‘functional barrier’ from the food. Therefore, active and intelligent packaging systems fall within the scope of framework Directive 89/109/EEC. According to article 2, they shall not endanger human health, nor change the food’s sensory characteristics. The latter requirement may be influenced by personal preferences and could be an issue of discussion. In addition, in further specific directives like 2002/72/EC 8 an overall migration limit of 60 mg/kg food is established as a purity requirement. Active systems developed to release certain components most likely will not comply with this requirement. To provide clarity, the scope of Directive 89/109/EEC should be extended to allow intentional migration from food contact materials at levels exceeding 60 mg/kg. 470 Novel food packaging techniques Intentional migration of substances has an effect on the composition of the food. It should be emphasized that the released substances are subject to various relevant regulations pertaining to food ingredients, food additives, labelling, etc. Intelligent packaging systems shall comply with Article 2, so no additional provisions in the framework directive are considered necessary. Specific measures may be required to regulate the chemicals used in the intelligent packaging systems, but this is a subject of specific directives. Recommendations for extending Directive 89/109/EEC Based on the results of the Actipak project, amendment of Directive 89/109 has been proposed, and the proposals have been adopted for implementation. A revised Directive will include an extended scope that mentions the allowed use of active and intelligent food contact materials. Special attention will be given to releasing packaging systems. The food in contact with such systems shall comply with any relevant food or food additive regulation. The releasing active packaging systems will be limited to materials that release substances added for that purpose. This means that natural materials, for example wooden barrels for wine or whisky storage, are excluded from the definition of active food contact materials. Proper labelling will also be required. This includes the conditions (time and temperature) in which the system can be brought into contact with the food and the food that may be in contact with a releasing system. As food additive regulations have to be obeyed the food packer should be informed about the amount of substance released from one object. Annex I of the Directive will be extended with active and intelligent systems. Annex I contains a list of materials, covered by specific measures. This means that in the future a specific directive will be drafted on active and intelligent packaging systems. 22.5.2 Directive 80/590/EEC 9 Symbol for food contact materials In Directive 80/590/EEC the symbol to be used for food contact materials not already in contact with foodstuffs is introduced. The symbol shall be used according to the requirements of Directive 89/109/EEC. Alternatively, subjects may be accompanied with the words ‘suitable for food contact’. Relevance to active and intelligent packaging systems Both active and intelligent packaging systems will not be available to consumers, as they usually require special care before bringing them into contact with foodstuffs. The final user of the A&I systems has to be informed that the subject is suitable for food contact, and thus the systems have to be labelled accordingly. Options are to print the symbol on the system or, at the wholesale stage, to add documentation with this symbol or proper wording. In those cases where a system as such is available to consumers the system should also be labelled in accordance with the requirements of this directive. Legislative issues relating to active and intelligent packaging 471 Recommendations Directive 80/590/EEC should be followed. There is no need for amendment of this directive. 22.5.3 Plastics directives Directive 2002/72/EC sets requirements for food contact materials manufactured solely from plastics. The composition of plastics permitted as food contact materials is based on the principle of a positive list. Maximum allowed migration limits of plastic components are based on the toxicological properties of substances. An overall migration limit of 60 mg/kg food or 10 mg/dm 2 is set to prevent contamination of the food to an unacceptable level. The directive is intended to harmonize certain classes of substances such as monomers, starting materials and additives. Polymerization regulators are not covered by the directive, but they shall not endanger human health according to framework Directive 89/109/EEC. In some countries, including the Netherlands and Germany, these substances are regulated at a national level. Article 8 of Directive 2002/72/EC requires verification of compliance with the requirements of the directive in accordance with the rules laid down in Directives 82/711/EEC and 85/572/EEC. In addition, the materials and articles shall be accompanied with a declaration of compliance at the marketing stage rather than the retail stage. Relevance to active and intelligent packaging systems Active packaging systems manufactured solely from plastics must comply with the requirements of Directive 2002/72/EC, meaning that composition and migration behaviour must be in compliance with the positive list and the migration restrictions. Active packaging systems, such as some types of oxygen absorbers, based on active ingredients that are incorporated in the backbone of the polymer shall comply with the directive. It is argued that these materials may be used to wrap the food in the same way as conventional packaging materials. This means that all substances used should have been evaluated by the SCF and be added to the positive list with or without a specific migration limit. Plastic materials and articles containing a substance intentionally released to the food should be treated differently. The base polymer should comply with Directive 2002/72/EC, whereas the released substance should be an approved food ingredient or food additive. Listing of the released substances on the positive list for plastics seems unnecessary as these substances should be allowed as food ingredients or food additives. However, allowance of the presence of such substances should be provided for in the plastics directive. Overall migration from releasing materials or articles may conflict with the overall migration limit. A requirement of enforcement authorities may be the possibility to check the overall migration of the polymer itself. In principle, this could be determined by the classic determination of the overall migration and subsequent subtraction of the specific migration of the released substance. However, in many cases the amount of released substance may be much higher 472 Novel food packaging techniques than the overall migration limit and the analytical error may be even higher than the overall migration limit itself. As a matter of fact, the plastic material can only be verified for compliance if the plastic is available without the releasing substance. This would require either enforcement of the plastic material at an early stage or demonstration of compliance by a reliable and acceptable certification procedure. Homogeneous intelligent systems manufactured from plastics only (mono- and multi-layers) and in which the intelligent ingredients are immobilized in the polymer backbone or blended as an additive in the plastic should comply with the requirements of Directive 2002/72/EC provided they are intended to come directly into contact with the food. Two types of composed materials and articles can be identified. First, there are systems that are manufactured by packing the active or intelligent ingredients in a plastic bag or box. Such a system is usually inserted into the primary package with the foodstuff. The plastic part of the system should be in compliance with Directive 2002/72/EC. However, the ingredients packed inside cannot be considered as plastic. These systems should be considered an entity of a food contact material and hence the whole system is excluded from the plastics regulation. Special provisions will be required to include this type of food contact materials. Systems of a second type are composed of various types of packaging materials, such as plastic, paper, metal, printing, adhesives, varnish and active or intelligent ingredients. Usually the individual components of the final system are hard to recognize. Such composite materials and articles are not covered by Directive 2002/72/EC. It is most likely that no EU regulation exists on the individual parts of the system. Regulations for paper, metal, printing inks and varnishes exist at the national level of some member states, waiting for harmonization at the EU level. This means that these systems are subject to national regulations and to the framework Directive 89/109/EEC. Both for enforcement authorities and for manufacturers this is an uncomfortable situation as it is difficult to establish the safety of these types of food contact materials. It seems realistic to assume that fully harmonized legislation on all types of food contact materials will not be available in the short term. Concerning active and intelligent ingredients, it was found that some are already included in a positive list, such as iron oxide used in oxygen absorbers, but many others are not. However, all these substances need to be regulated to avoid their use is forbidden without firm grounds and the possibility that unsafe situations may occur. Therefore, if there is direct contact with the food, the system should be submitted to migration testing protocols and the relevant substances should be toxicologically evaluated and subsequently added to a positive list. Frequently applied intelligent systems, such as time/temperature indicators, are positioned on the outside of the primary food packaging. In addition, these systems are usually made of plastic and connected to the packaging by an adhesive layer. Use of time/temperature indicators almost automatically implies Legislative issues relating to active and intelligent packaging 473 that storage times are relatively short and temperatures are low. Taking this into account the probability of migration through the primary packaging into the food is negligible. These types of intelligent systems should not be considered as food contact materials with respect to migration testing. Nevertheless, it may be necessary to include ‘intelligent substances’ in a positive list for which toxicological evaluation can be kept to a minimum. Recommendations ? Active and intelligent packaging systems manufactured from plastics only shall comply with the compositional and migration requirements (except for intentionally released substances). ? Substances intentionally released from an active releasing system shall comply with relevant requirements for food and food additives. Provisions should be made for allowance of migration values higher than the overall migration of 60 mg/kg food. ? It is proposed to draft a specific directive in which active and intelligent packaging systems are regulated. For regulation of composite materials reference to existing national regulations with regard to the base packaging materials and separate listing of the active and intelligent ingredients seems the best solution for the time being. ? Active and intelligent packaging systems should be accompanied with a declaration of compliance provided the provisions proposed have been realized. ? It will remain very difficult and laborious for enforcement laboratories to prove violation of Article 2 of Directive 89/109/EEC for complex systems. For manufacturers it may be difficult to demonstrate compliance with the rules, as they are usually not aware of the composition of all parts of the final article. A proper certification system may provide a better guarantee of the safety of the packaging system. Proper rules and guidelines, as well as the appointment of recognized certification laboratories would be required for that purpose. The scheme given in Fig. 22.2 could be a starting point for drafting a certification procedure. 22.5.4 Basic rules for migration tests At the EU level, rules for testing plastic food contact materials are given in 82/ 711/EEC 10 as amended by 93/8/EEC 11 and 97/48/EEC. 12 Directive 85/572/ EEC 13 provides a list of simulants that could replace real foodstuffs in migration testing. Simulants prescribed for compliance testing are water, 3% acetic acid, 10% ethanol or olive oil. In some cases olive oil may be replaced with the substitute food simulants 95% ethanol and iso-octane. In Directive 85/572/EEC it is recognized that a fat simulant may be a stronger extractive than the food. Depending on the food and its fat content reduction factors are included in the list. This means that the migration value obtained with a fat simulant should be divided by the value indicated for that particular food. The reduction factors vary from 2 to 5. 474 Novel food packaging techniques In Directive 97/48/EC detailed conditions of time and temperature are given to demonstrate compliance with the limits set in Directive 2002/72/EC. The test conditions to be applied shall represent the worst foreseeable conditions of use in case of contact with foodstuffs. Food contact materials and articles should be accompanied with a statement indicating the restrictions of use, if any, with respect to the types of food and the maximum contact conditions of time and temperature, according to Article 6 of Directive 89/109/EEC. Fig. 22.2 Scheme for certification procedure. Legislative issues relating to active and intelligent packaging 475 Directive 97/48/EC explicitly mentions that, if the food contact material under specified contact conditions shows physical or other changes that do not occur under conditions of use, the migration test shall be carried out under the worst foreseeable contact conditions of use in which these physical or other changes do not take place. This article allows for the use of specially developed testing protocols depending on the problems encountered in the standardized testing protocols. However, the test protocols are applicable only to materials made of plastic. This means that materials composed of one or more layers not made of plastic are not covered by the EU regulation. At a national level, for example in the Netherlands, the testing protocols are used for most types of food contact materials. Detailed methods in which the requirements of these directives are taken into account have been drafted and validated by the European Standardisation Committee (CEN) in EN 1186 and EN 13130. Relevance to A&I packaging systems The appearance (size and shape) and the composition of active and intelligent packaging systems depend on their application. Systems used to wrap the food and made of plastics solely can be examined according to the requirements of Directive 82/711/EEC. If such a system intentionally releases substances to the food, then technically the system can be examined according to the requirements of Directive 82/711/EEC, but it may exceed the overall migration limit without endangering human health, changing the composition of the food in an unacceptable way or deteriorating sensory properties. Therefore these systems would require a special approach in interpretating migration values. Most active and intelligent packaging systems are composed of various (non- plastic) materials. In principle, these materials are excluded from EU regulations. However, at a national level the same testing protocols are applied to most other non-plastic food contact materials. In contrast to conventional packaging materials and articles, active and intelligent packaging systems have often a very limited surface area compared to the food in contact with them. Many of these systems are not intentionally in contact with the food but only by accident. For example, a sachet with an oxygen absorber may not be in contact with the food at all at the stage of packing. During transport or handling in a retail shop the food may make contact with the absorber, but only a relatively small area of the food will be in contact with the absorber sachet. Nevertheless, migration may occur and migration testing is required to guarantee food safety. The test conditions of time and temperature can be selected from Directive 82/ 711/EEC, and the appropriate simulants from Directive 85/572/EEC. For active and intelligent packaging systems in contact with dry foodstuffs (without free fat on the surface) no migration tests with simulants are prescribed. If necessary, the specific migration of substances should be measured in the food itself. Systems in contact with aqueous or fatty foods require testing with simulants. In principle, the protocols prescribe that food contact materials are brought into contact with a food simulant. This can be achieved by total immersion or by one- sided contact of the material with the food simulant. One-sided contact of plastic 476 Novel food packaging techniques materials is achievable by filling an article such as a bottle or by using a migration cell for one-sided contact. Due to the construction of many active and intelligent packaging systems this approach is not feasible, and only submersion of the article is an option. The conditions of contact and, as a consequence, the migration of substances during submersion in food simulant may deviate severely from the conditions of contact occurring under real conditions of contact. For example, the conditions of contact of a small oxygen absorber with roasted nuts are not comparable to submersion in a fat simulant, not even when the allowed reduction factor is applied. When submersing the oxygen absorber in oil the whole article is soaked with oil, which does not happen when it is in contact with nuts. Comparable situations were observed when using systems in contact with meat, for which Directive 85/572/EEC requires testing with water and oil. The tests with water and, in case of processed meat products, with 3% acetic acid by total immersion results in excessive migration of iron ions into the food simulant. After the migration period the food simulant is usually brown- coloured by iron oxide. This phenomenon does not occur with foodstuffs; otherwise, the food contaminated with brown spots would not be acceptable from a sensory point of view. In the case of moisture absorbers, submersion of the absorber leads to contact conditions significantly different from those occurring in contact with food under real conditions as well. Active and intelligent packaging systems are in contact with the foodstuff under different conditions from conventional packaging materials. In addition, the composition (multi-layer) of the system, as well as the presence of an active ingredient, are reasons for high migration when testing under conventional conditions. Therefore, there is a need for extending the existing test protocols with so-called dedicated test methods. Within the Actipak project some experiments with dedicated tests have been performed. Oxygen-absorbing labels were tested by sandwiching the label between layers of filter paper immersed in iso-octane as the fatty food simulant. After the migration period the paper was extracted and the overall migration was determined. Migration from a paper fibre-based moisture absorber was determined with a block of agar. The agar immobilizes the water in a comparable way as water bound in meat, for example. To demonstrate potential migration the absorber was first partly saturated with water containing a fluorescent label. After the contact period the migration of the fluorescent label was measured. This test could be useful to demonstrate whether or not migration may occur. Similar tests were performed with a moisture regulator based on the hygroscopic properties of sugar solutions. Migration of iron and sodium chloride from an oxygen absorber in real food, food simulants and alternative simulants has been determined as well. The results are very promising, but need further standardization and validation. Intelligent systems placed on the outside of the primary packaging may form a separate group. These intelligent systems are connected to the packaging material by means of an adhesive. Many intelligent systems are composed of plastic material that contains the intelligent ingredients as one of the layers of Legislative issues relating to active and intelligent packaging 477 the system or in a plastic sachet. There is no direct contact with the food. In addition, the shelf-life of foods with an intelligent system on the outside is relatively short. Even if a polyolefin is used for the primary packaging the lag time will prevent any migration. There is no need yet to require migration testing of intelligent systems connected to the outside of the primary packaging. Recommendations ? Active and intelligent packaging systems composed of only plastic shall be tested according to Directives 82/711/EEC and 85/572/EEC. ? Substances intended to be released from an active system could be quantified by migration testing or by determination of the total amount present, while assuming that the total amount of substance present in the active system will be released to the packed food. ? The annex of Directive 97/48/EC should be extended to allow testing with foodstuffs too. ? Article 1 (4) of Directive 82/711/EEC should be amended to allow application of the provisions of the Directive to active and intelligent packaging systems not composed of plastics only. ? Intelligent systems placed on the outside of the primary packaging should be excluded from migration testing. Clause 4 of Chapter II of the Annex of Directive 97/48/EEC should be extended for that purpose. ? An additional Chapter V in the Annex of Directive 97/48/EC should be inserted to allow for dedicated test protocols for some types of active and intelligent packaging systems. ? Dedicated test protocols need further development and standardization. 22.5.5 Other directives on food contact materials Other specific directives concerning food contact materials have been published. However, these directives do not influence the use of active and intelligent packaging systems and are hence not discussed here in detail. For the sake of completeness, these directives are listed below. 93/10/EEC 14 regenerated cellulose film 93/111/EC 15 1st amendment to Directive 93/10/EEC 84/500/EEC 16 ceramic articles intended to come into contact with foodstuffs 2002/16/EC 17 use of certain epoxy derivatives 22.6 Food additives The requirements for food additives are formulated in general terms in Frame- work Directive 89/107/EEC. Specific directives have been published on colours, sweeteners and food additives other than colours and sweeteners. 478 Novel food packaging techniques 22.6.1 Framework Directive 89/107/EEC 18 as amended by Directive 94/34/ EEC 19 Directive 89/107/EEC specifies the definition for food additives and the scope of the directive. In simple terms, it states that food additives are not food ingredients or characteristic ingredients. Food additives are intentionally added to attain a technological effect during manufacturing, storage and distribution of the food. Various categories of food additives have been identified, each with its typical properties. Food additives are allowed only if there is a technological need, if there is no hazard to human health and if they do not mislead the consumer. Consumers should be informed about the presence of additives in foodstuffs by means of proper labelling of the food or the food additives. At a national level specific requirements on listing the ingredients as well as their traceability may exist. Relevance to active and intelligent packaging systems The directive on food additives is relevant only to systems that intentionally release substances into the food. The substance intentionally released from an active system should in the first place be an allowed food additive covered by one of the categories listed in Annex I of Directive 89/107/EEC. In addition, there should be a technological need that cannot be met by other means. Validity of this clause may be difficult to demonstrate but active systems fulfil a technological function in the food when food is already packed. In addition, the requirement to add the lowest level possible to achieve a desired effect may support the use of active systems. Active systems usually will be active at the surface of the packed food, whereas a food additive is often mixed into the food. As a result, the total amount of a substance may be significantly reduced when using an active system. Foods may contain a substance that is also released from an active packaging system. In those cases, the final concentration in the food should be taken for a proper judgement of compliance with regulatory requirements. The food packer will carry that responsibility in first instance. The proper labelling of the active releasing system concerning the maximum amount of substance released from an active system avoids the possibility of that maximum limit being exceeded. Active releasing systems may release the food additive via the headspace of the packed food to obtain a distribution as uniform as possible. In other cases the transfer of substances may be caused by intense contact with the active system. In both cases the concentration at the surface may be higher than the maximum allowed concentration. However, measured on the basis of the bulk of the food the amount of food additive should be significantly below the allowed concentration limit. Taking into account that the whole bulk of the packed food is consumed this should not be a problem. In analysis of the foodstuff a proper homogenization of the food should be ensured. Recommendations ? Directive 89/107/EEC does not form any hurdle to the use of active and Legislative issues relating to active and intelligent packaging 479 intelligent packaging systems. The substances released from active packaging systems shall comply with the requirements of this directive. ? Foods in contact with a releasing system should be homogenized before analyzing the food on the total amount of the relevant food additive. 22.6.2 Specific directives on colours, sweeteners and food additives other than colours and sweeteners In addition to the Framework directive, specific directives on food additives have been published. Directive 95/2/EC 20 (last amended by 2001/5/EC 21 ) provides a glossary of the various categories of food additives covered by the directive. Also substances not included in the directive are indicated, for example substances for the treatment of drinking water. The directive is based on the positive list principle. The substances, provided with a so-called E number, are listed in five separate annexes. The annexes list substances for general use or for use in specified foods or concentrations. A relevant issue is the packaging gases that are allowed in all foodstuffs. In this respect, the Directive defines packaging gases as gases other than air, introduced into a container before, during or after placing a foodstuff in that container. Packaging gases provided with an E number are carbon dioxide, argon, helium, nitrogen, dinitrogen oxide and oxygen. The additives are subject to purity requirements, which are laid down in specific directives. Requirements for colours used in foodstuffs are laid down in Directive 94/36/EC. 22 Colours allowed to add or restore colour in foodstuffs include colours of natural sources. In five annexes the permitted colours and the conditions of their use are laid down. The annexes include a positive list, a list of foodstuffs that may not be coloured, and colours with restricted uses. Directive 94/35/EC 23 (as amended by Directive 96/83/EC 24 ) concerns the use of sweeteners added to foodstuffs. Only the sweeteners listed may be used in the foodstuffs listed at a level fulfilling the intended purpose and shall not mislead consumers. Relevance to active and intelligent packaging systems The specific directives of the framework Directive 89/107/EEC are relevant only to releasing systems. The specific directives are detailed and do not allow deviations. Therefore, the releasing systems should comply with qualitative and quantitative requirements on food additives. Manufacturers and food packers should realize that a releasing system may not be generally applicable to all foodstuffs but only to specified ones. Therefore, it seems obvious that the manufacturer of releasing systems should give proper instructions and define conditions of use, although the final user or food packer has his own responsibility as well. None of the specific directives mentions the removal of substances from the packed foodstuffs. This may be logical as the directives are dealing with 480 Novel food packaging techniques additives. The use of an oxygen absorber, which removes oxygen from the headspace of the packed food, is excluded from the directive whereas flushing with nitrogen is included. The resultant packaging gas is, however, similar. The application of gas absorbers is not covered by any directive and remains the responsibility of the food packer. As the application of oxygen absorbers is very similar to the use of packaging gases, it seems logical that labelling and food safety are handled in the same way. Labelling of packed food Packaging gases used for packaging certain foodstuffs should not be regarded as ingredients and therefore should not be included in the list of ingredients on the label. However, consumers should be informed of the use of such gases inasmuch as this information enables them to understand why the foodstuff they have purchased has a longer shelf-life than similar products packaged differently. Therefore, the following text should be used on the label in the national language: ‘packed under a protective atmosphere’, as is required for modified-atmosphere packaging Food safety When the atmosphere inside a package is altered, the limiting factor for shelf- life may also change. For example, in an oxygen-free atmosphere the growth of aerobic micro-organisms is inhibited, but this atmosphere may promote the growth of anaerobic micro-organisms. The limiting factor for shelf-life may then become the growth of anaerobic micro-organisms. A similar reasoning may be valid for preservative-releasing systems. Shelf-life studies should reveal the spoilage mechanism and the actual shelf-life of the food should be established. Recommendations ? Food additives released from active packaging systems shall comply with the requirements laid down in the framework directive and its subsequent specific directives. Limits and requirements on the total quantity of additives in foods and the purity of the additives shall be obeyed. Also the limitation of addition of substances to specified foods must be taken into account. ? Oxygen absorbers should be included in the section about modified- atmosphere packaging by amending Article 1(3 r) of Directive 95/2/EC as follows: ‘packaging gases’ are gases other than air, introduced into a container before, during or after placing of the foodstuff in that container, or by selective removal of oxygen after placing of the foodstuff in that container’ ? Substances released into food shall be labelled according to requirements on labelling. Legislative issues relating to active and intelligent packaging 481 22.7 Food flavouring Framework Directive 88/388/EEC 25 (as amended by 91/71/EEC 26 ) concerns flavouring substances for use in or on foodstuffs to impart odour and/or taste. The flavouring substances should be obtained from materials of vegetable or animal origin or by chemical synthesis. Flavourings should not imply addition of any element or substance in a toxicologically dangerous quantity. Maximum levels for arsenic, lead, cadmium and chromium have been set. Also the content of 3,4-benzopyrene is limited in all foods. There is a short list of substances that may be used at certain maximum concentrations in foodstuffs. Labelling requirements concerning the description, quantity, suitability for food use and traceability have been laid down. In Council regulation EC 2232/ 96 27 a procedure is laid down which includes the listing of all flavouring substances in use in the EU member states. The substances will be evaluated to establish their conditions of use. Commission decision 1999/217, 28 as amended by Commission decision 2000/489, 29 lists more than 2800 substances The registration is a first step to a harmonized positive list of flavouring substances. The Nordic countries have some specific rules for the use of flavourings in certain food products. 3 Relevance to active and intelligent packaging systems Active packaging systems releasing flavourings are by definition an attractive way of flavouring food. A flavour added to the packed foodstuff will generate an attractive or characteristic smell when consumers open the packed food. Sausage casing may be flavoured to release the smoke flavour to the sausage in order to obtain a flavour taste and to preserve the sausage. A classic example is the use of wine barrels, which are used to store the wine but at the same time release their flavour to the wine, which may be characteristic of the wine. In modern wine making wood chips may be used to obtain the same effect. Although a wine barrel is clearly an active packaging material in the definition of active packaging systems, for historical reasons and because of the natural origin, wine barrels could be excluded from classification as an active packaging material. Application of flavour-releasing systems will not be hindered by the existing regulations on flavouring, provided the rules laid down for flavouring of foodstuffs are taken into account. Release of flavour, can however, also be used to hide some negative aspects of the foodstuff. Directive 88/388/EEC clearly indicates that flavouring must not be allowed to mislead consumers. The use of flavouring to hide spoilage is not acceptable; it would mislead consumers and may cause serious food poisoning. But, when the flavour is added in order to overwhelm an off-flavour of the food and the use of flavouring does not cause any toxic harm it may be found acceptable. Active flavour-releasing systems are also strong tools to avoid so-called scalping of flavour of packed foods. By supplementing the flavours through the packaging material this effect could be avoided. 482 Novel food packaging techniques Another category of active packaging systems that may mislead consumers are absorbers. For instance, an absorber could be used to remove the amine smell of fish and, as a consequence, consumers will be deprived of a sensory indicator for spoilage. These types of active systems are not covered by the flavouring regulations but are actually comparable to hiding effects or, in the worst case, misleading consumers. Recommendations ? There are no fundamental objections to the use of an active system that releases flavouring substances, provided the regulations on flavouring are followed. ? Allowed total quantities of flavourings in foods shall not be exceeded. ? Flavouring to hide spoilage is not allowed. ? Flavouring to mask natural or synthetic off-flavours should be further studied. Conditions of acceptability should be drafted. ? Removal of substances is not an issue of the flavouring regulation but needs legal attention. Appropriate provisions could be included in the specific directive on active and intelligent food contact materials. 22.8 Biocides and pesticides Biocides are substances intended to destroy, deter, render harmless, prevent the action of, or otherwise exert a controlling effect on any harmful organism by chemical or biological means, as defined in Directive 98/8/EC. 30 Several areas are excluded from the directive. Among others, food additives subject to Directive 89/107/EEC and food contact materials subject to Directive 89/109/ EEC are excluded from the biocide regulations. 22.8.1 Relevance to active and intelligent packaging systems The biocide regulation excludes food additives and food contact materials. Thus, any substance with a biocidal effect should be listed in these regulations. Active systems intended to release a biocidally active substance into foods are limited to the use of substances allowed as food additives. All requirements and restrictions laid down in the regulations on food additives must be taken into account. Only in bulk transport is the use of biocides as well as pesticides allowed. A ship cargo space may be gassed with biocides or pesticides to protect the food. This may also be feasible with active systems of sufficient capacity. This is considered a special category of application that should comply with the rules presently valid. Often confusion is brought about with regard to the use of biocidal substances in food contact materials. There are two reasons to add biocidal products to food contact materials. First, it may be necessary to stabilize a polymer emulsion before manufacturing the final article. This application is indispensable to allow Legislative issues relating to active and intelligent packaging 483 transport and storage of the semi-manufactured product. A second application, of increasing interest, is the addition of antimicrobial substances to protect the surface of the final article from microbial contamination. In both situations the addition of the biocide should not be considered as an active system as there is no intentional influence on the food. In both cases migration of the substance should be negligible or as low as possible; anyway, there should be no effect on the food in contact with the materials. Recommendation The regulation on biocides excludes food contact materials and food additives. Therefore, all applications related to biocidal substances are subject to regulations on food contact materials and food additives. 22.8.2 Pesticides Directive 91/414/EEC 31 regulates the use of pesticides, which, in short, are active substances to protect plants and plant products against harmful organisms. Plant protection products (pesticides) are used on agricultural produce and are not added to foodstuffs as preservatives. Maximum residue levels (MRLs) for each specific pesticide in agricultural produce have been defined in the Directive, either for a group of products or for individual products. 22.8.3 Relevance to active and intelligent packaging systems The use of pesticides is legal only if approved for a specific use or on specific agricultural produce. At the pre-harvest stage the use of active packaging is unlikely even if possible. However, some products may also be treated with pesticides at the post-harvest stage; for example, the use of certain plant growth regulators for potatoes is authorized as well as some insecticides on cereal grains. The use of these pesticides is usually a matter of bulk treatment. Protective substances on potatoes or cereal grains may or may not be volatile. Treatment with non-volatile agents is unlikely as it will not be effective on the bulk of food. The protection of potatoes with volatile substances may be feasible but due to the batch treatment this is unlikely. No such applications are currently in use or under development. When active systems are developed then they should comply with the rules on treatment of food products. Impregnation with biphenyl of paper used for packaging citrus fruits has been known for many years. However, in this application biphenyl is regulated as a food additive. Recommendation When active systems are developed, they shall comply with the regulation on pesticides. 484 Novel food packaging techniques 22.9 Food hygiene The aim of Council Directive 93/43/EEC 32 on the hygiene of foodstuffs is to control all activities critical to food safety, and thus it covers all aspects affecting hygienic production, storage, packaging and distribution of foodstuffs, in order to ensure the safety and wholesomeness of foodstuffs. The Directive aims at establishing uniform minimum requirements for food production to ensure that only safe food is retailed. Regulations on veterinary products, such as Directive 92/5/EEC 33 for meat products, contain more detailed requirements (e.g. approval of establishment, stricter temperature conditions, official controls) for the production of some products of animal origin. Special provisions for the hygiene of quick-frozen foodstuffs are given in Council Directive 89/108/EEC 34 to protect them from microbial or other external contamination and from drying. To achieve safe food the directive requires protection of the food within the food production chain against any contamination that renders the food unfit for consumption. Foods supporting the growth of pathogenic micro-organisms or the formation of toxins should be kept at temperatures that will not endanger health. Principles of HACCP (hazard analysis of critical control points) as given by the FAO/WHO Codex Alimentarius Commission 35 should be followed. Food packaging materials are not directly covered by the EC Directive, but hygienic conditions of the packaging materials will be a prerequisite in hygienic food production. Neither the microbiological criteria for foodstuffs nor the temperature requirements have been harmonized in the European Union. Various time-temperature requirements can therefore be found for certain food categories in different countries. 36 Where no legislation exists, the manufacturer may freely choose the best storage temperature for the product provided the product is safe for consumption. Although legislative requirements and recommendations for temperature control during manufacturing, heating, cooling and chilled storage are abundant, there are no rules in food legislation on how long food quality should remain acceptable. Directive 2000/13/EC 37 on labelling requires pre-packed foods to bear a date of minimum durability or, for highly perishable foods, a ‘use by’ date. It is the manufacturer’s responsibility to determine the shelf-life of the product, taking into account storage conditions, and to ensure that the product is safe throughout its assigned shelf-life. The shelf-life of foods depends on the specific properties of the food product and the environmental conditions in which the food is treated and stored. In particular, the shelf-life of microbiologically sensitive foodstuffs will depend on storage conditions of time and temperature. 22.9.1 Relevance to active and intelligent packaging systems The Food Hygiene Directive requires that all measures be taken to ensure the safety and wholesomeness of foodstuffs during production, transport, storage and offering for sale or supply to the consumer. The use of active systems may Legislative issues relating to active and intelligent packaging 485 be helpful to maintain the quality of the food and to extend its shelf-life. Intelligent systems could provide reliable information on the conditions of the food by showing, for instance, the time and temperature conditions during the life cycle of the food, or by detecting gases generated by micro-organisms. The use of an oxygen absorber will suppress the growth of certain micro- organisms. The use of preservative-releasing systems will have a similar final effect. Foodstuffs will not only have a longer shelf-life but will also be safer at the time of consumption. The use of moisture absorbers, for example for packaged meat, has in the first instance a visual benefit as the meat juice is absorbed by the absorption pad. If, however, such a pad is treated with a selected mixture of spices, then microbial deterioration will be slowed down resulting in a longer shelf-life and safer product. It is required today to print on packaged food the ‘use by’ date. Usually the ‘use by’ date is established on the basis of experience. For products with a long shelf-life this does not cause any problem as the storage time and temperature conditions are not very critical. For products with a long shelf-life chemical deterioration is usually the limiting factor, whereas for foods with a relatively short shelf-life microbiological conditions are often the limiting factor. Food packers may extend the safety margin to allow of some ‘misuse’ during transport by consumers from the retailer to their homes, or incorrect temperature settings during display. Use of a time/temperature indicator could indicate the safety of the food by indicating that the allowable storage conditions of time and temperature have not been exceeded. These time/temperature indicators could prevent unnecessary waste of food due to the elapse of the ‘use by’ date, which of itself is no guarantee that the food is fit for consumption. The indicator will inform consumers whether the product is still suitable for consumption. These indicators could replace the requirements of printing ‘use by’ dates when it is demonstrated that they are reliable and when the consumer is familiar with the use of the indicators. However, most time/temperature indicators are not capable of giving proper information on the period still to go before the ‘use by’ date is passed. This could be overcome by printing the production date or date of packing on the packed food instead of a ‘use by’ date in addition to an indication of the shelf-life. This approach would require, of course, a range of indicators with variable ‘response times’ to allow the use of a proper indicator. Modified-atmosphere packaging with packaging gases is a frequently used method to preserve foods. However, if the gas-tightness of the package fails, the protective atmosphere will change and the food may become unfit for consumption. This is very difficult to observe both for the manufacturer and for consumers. Insertion of an indicator that detects, for example, oxygen will provide information not available without the indicator. Similar indicators can be inserted to detect the generation of microbial respiratory gases. The Food Hygiene Directive requires ‘all measures necessary to ensure the safety and wholesomeness of foodstuffs’. The use of both active and intelligent packaging systems is a new means of meeting this requirement. Actually, the requirements of the hygiene directives strongly support the use of active and intelligent systems. 486 Novel food packaging techniques Recommendation Allowance should be made in the Food Hygiene Directive to replace the ‘use by’ date with dedicated time temperature indicators. 22.10 Food labelling, weight and volume control Labelling of foodstuffs is meant to give consumers information on the composition of the food and to protect them. In Directive 2000/13/EC requirements for labelling of foodstuffs to be delivered to the ultimate consumer are laid down. Labelling of the foodstuff should not mislead the ultimate consumer. Detailed but generally applicable requirements have been formulated as to the information to be provided. Major issues are: name, list and quantities of ingredients, shelf-life, name and address of the manufacturer, instructions for use, etc. All ingredients should be listed in descending order of quantity. Food additives shall be designed by their category name followed by their specified name or EC number, for example ‘Emulsifier E 322’. Also requirements on the minimum durability of the foodstuff should be printed by using the wording ‘best before . . .’ or ‘use by . . .’ depending on the perishable nature of the foodstuff. Directive 89/109/EEC lists requirements on labelling of packaging materials. This concerns, however, not the final product but the packaging material when it is not in contact with the food. In that case the packaging material should be accompanied with instructions for use such as suitability for various types of foodstuffs and maximum temperature range. In addition, it should be possible to trace back the packaging material to the manufacturer in case of a calamity. 22.10.1 Relevance to active and intelligent packaging systems Directive 2000/13/EC requires listing of food additives used in the manufacture or preparation of foods and still present in the finished product. It may be questionable whether an additive released from the packaging material is added during manufacturing or preparation, but no doubt it will be present in the final product. Therefore, any substance intentionally released into the food while being packed should be listed according to the rules of Directive 2000/13/EC. Requirements on total quantities should be respected, irrespective of the stage at which the substance becomes part of the foodstuff. Intelligent systems could supplement the information presently given to the consumer. It is conceivable that labelling requirements could be changed due to the information given by intelligent systems. For example, ‘use by’ dates could be replaced by information obtained from a time-temperature indicator. However, the introduction of intelligent systems and consumer education regarding interpretation will be needed before making any changes to labelling requirements in this respect. Active and intelligent packaging systems may be incorporated in the packaging material of the foodstuff. They can also be packed with the food in Legislative issues relating to active and intelligent packaging 487 the form of a sachet, box or label. Consumers should be made aware that the object included in or on the packed food is not a part of that food. Sachets with a powder could easily be confused with ingredients like salt or pepper. Great care should be taken to prevent the consumers eating it. Labelling only by text seems not sufficient. Consumers who cannot read must be protected as well. Therefore, the introduction of a harmonized universal symbol, which indicates that the object is not part of the foodstuff, seems appropriate. According to labelling Directive 2000/13/EC, the ultimate consumer should be informed properly. Therefore, also information on the function of the inedible active or intelligent packaging system, should be printed. Usually, active and intelligent packaging systems will not be available to the consumer as such. They will be purchased by food manufacturers and food packers. The manufacturers should also be informed about the range of applications and restrictions of use as well as about the quantity of additive that may be released from an active system. This could be achieved by means of documents attached to a batch of articles. Recommendations ? Labelling of foods shall be in compliance with Directive 2000/13/EC. Substances released from a system should be considered a food additive added during manufacturing or preparation of the food. ? Requirements on labelling, at the retail stage, should be formulated with the aim to inform the consumer about: – the presence of a non-food component – the function of the system – inedibility of the system by means of written text and a pictogram – any possible risk upon digestion of a system. These requirements could be added to the directive on labelling, but it may be more appropriate to add them to the specific directive on active and intelligent food contact materials. ? At the wholesale stage, active and intelligent packaging systems should be accompanied by a certificate of compliance with regulations of food contact materials. ? Instructions on conditions and restrictions of use should be given at the wholesale stage. 22.10.2 Weight and volume control Several EU directives deal with the weight and volume control of pre-packaged food. Directive 75/106/EEC 38 and Directive 76/211/EC 39 relate to pre-packages made up by volume and weight respectively. The pre-packages must bear an indication of the product weight or volume, known as ‘nominal weight’ or ‘nominal volume’ which they are required to contain. 488 Novel food packaging techniques 22.10.3 Relevance to active and intelligent packaging systems Active systems may influence the weight or volume of the foodstuffs. In the case of emitters of food additives (preservatives, flavouring compounds, etc.) the migration of these compounds will have a negligible effect on the weight or volume of the food. Lightweight foods, such as chips and dried herbs, may be exceptions. Moisture absorbers, such as an absorbing pad for meat drip, usually have a noticeable effect on the net weight of meat. The aim of the Directives on weight and volume control is to ensure that consumers are correctly informed on the net quantity of the food. If the active system influences the weight or volume, this must be taken into account in the declared weight or volume. Recommendation Active packaging systems with absorbing properties should take into account the loss of weight due to the absorber. 22.11 Product safety and waste Directive 2001/95/EC 40 concerns general product safety. The general product safety directive dictates that all products placed on the market shall be safe. ‘Safe products’ mean that under normal or reasonably foreseeable conditions of use the product does not present any risk or only the minimal risks compatible with the product’s use. In the judgement of safety aspects the characteristics of the product, presentation, labelling instructions and the category of consumers, in particular children, should be considered. Manufacturers are obliged to provide the relevant information to the final consumer. 22.11.1 Relevance to active and intelligent packaging systems The general product safety directive applies to active and intelligent systems. The active or intelligent system may never endanger food safety or consumer health. To comply with safety a number of issues have to be considered before bringing systems on the market. 22.11.2 Labelling of active and intelligent systems Several active and intelligent systems are present inside the primary packaging, such as sachets, cups and pads. It has to be made clear that these systems are not suitable for consumption. There should be no confusion with sachets or cups that contain, for example, herbs, salt or butter, which are intended to be consumed with the packaged food. Therefore, on the active or intelligent system a well legible, indelible warning has to be placed in at least the national language that the active or intelligent system is not to be consumed, for example ‘DO NOT EAT’. Functionally dyslexic people and those not able to read the national language should be able to understand the warning ‘DO NOT EAT’ by means of a symbol Legislative issues relating to active and intelligent packaging 489 printed on the label. This symbol has to express that the content of the active or intelligent system is not suitable for consumption. Harmonization of the wordings and the symbol would enhance the understanding of the wording and symbol in a short period of time, whereas the use of different indications would confuse the consumer. Within the Actipak project a symbol is proposed which is shown in Fig. 22.3. Possibly better designs could be developed, but the main issue is that only one symbol should be adopted for harmonization. 22.11.3 Size and shape of active or intelligent systems A recommendation has been issued to member states to take action to prevent consumption of the non-food article. In this respect children, mentally disabled patients and elderly people are considered high-risk groups. It is therefore advisable that the non-food article is so large that adults cannot swallow it. For toys 41 the minimum size is determined on the basis of a defined cylinder, resulting in a size of 3.17 cm. For adults the minimum size should be increased to 5 cm. In addition, the non-food article should have a morphology distinguishing it from the packaged food. Another possibility is to thoroughly attach the active or intelligent system to the packaging. Content of active and intelligent system If, for any reason, the active or intelligent system releases its chemicals, no acute danger to the consumer may occur. Therefore, active and intelligent compounds present in sachets, cups or pads used in consumer packaging should not be seriously irritating, corrosive, harmful or toxic. Furthermore, these compounds shall not be carcinogenic. Directive 67/548/EEC 42 can be used to classify dangerous substances. Some active or intelligent systems consist of a film that incorporates the active compound. In these cases the Scientific Committee on Food has to assess their toxicity and migration behaviour and set limits accordingly. 22.11.4 Food imitation directive Products referred to in the Food Imitation Directive 87/357/EEC 43 are those which, although not foodstuffs, possess a form, odour, colour, appearance, packaging, labelling, volume or size such that it is likely that consumers, especially children, will confuse them with foodstuffs and consequently place them in their mouths, or suck or ingest them, which might have serious effects. Fig. 22.3 Proposed symbol to warn consumers not to eat the system. 490 Novel food packaging techniques Member states are obliged to take all measures necessary to prohibit the marketing, import and either manufacture or export of unsafe products. 22.11.5 Retail versus wholesale Active or intelligent packaging systems can also be used in wholesale food applications, for example, during transport of wholesale packaged foodstuffs. These active or intelligent systems will not reach consumers. The final users are then professional employees, not the risk groups of children, elderly people and mentally disabled persons. Therefore, active and intelligent systems used in wholesale that are not intended to reach consumers do not have to comply with the previously described safety aspects regarding the size and content, or the food imitation directive. Recommendations ? Measures should be taken to harmonize the text and symbol to be printed on active and intelligent packaging systems. ? Requirements on size and shape as laid down in toys regulations should be made applicable to movable objects packaged with foodstuffs. ? Quantities of substances that could have serious health or lethal effects should not be allowed. ? Directive 87/357/EEC on food imitation may be applicable to active and intelligent packaging systems depending on the appearance of the system. Manufacturers should consider this directive, in particular in the develop- mental phase of their system. 22.11.6 Waste Waste Directive 94/62/EC 44 describes measures aiming at preventing the production of packaging waste. It additionally aims at reusing, recycling or recovering packaging waste to reduce the final disposal of packaging waste. The directive covers all packaging placed on the market regardless of the material used. The directive is applicable to all types of packaging waste. Member states in communication with stakeholders are encouraged to promote reuse of packaging materials. Identification codes should facilitate collection, reuse and recycling. Restrictions as to the levels of lead, cadmium, mercury and hexavalent chromium must be reduced in time. The directive mentions the recycling processes actually available. The directive also assumes that materials can be reused only when appropriate. Packaging use shall be reduced to a minimum. Relevance to active and intelligent packaging systems In environmental issues it is often necessary to perform a life cycle analysis. Only in that way is it possible to establish whether the use of a certain type of Legislative issues relating to active and intelligent packaging 491 packaging material is the most appropriate. Addition of an active or intelligent packaging system may require an additional amount of packaging material resulting in more waste. However, if by virtue of a longer shelf-life of the packed food the waste of packaging material and food is reduced, the scale could easily be turned in favour of the use of active or intelligent packaging systems. Recovery of food contact materials, with the exception of paper, glass and metal, is limited. In recycling of plastics only recycled polyethylene terephthalate is commercially applied. For most other polymers recycling of food contact plastics into new articles is still on a modest scale. Collection, sorting, cleaning and processing is cumbersome, as the directives on plastics require that the material shall be safe and comply with the positive list. This means that recycling of complex mixtures like active and intelligent packaging systems is currently not an issue. The presence of various chemicals, present only in relatively small quantities, may meet objections upon incineration but if the substances are of organic nature they will be incinerated. Oxygen absorbers containing iron may produce some additional slag. In general, no problems are manifesting themselves now but developers of active and intelligent packaging systems should take into account possible environmental consequences. Recommendation ? Manufacturers should consider the use of active and intelligent packaging systems in view of environmental issues. 22.12 References 1. DE KRUIJF N, VAN BEEST M, RIJK R, SIPILA ¨ INEN-MALM T, PASEIRO LOSADA P and DE MEULENAER B, ‘Active and intelligent packaging: applications and regulatory aspects’, Food Addit Contam, 2002 19 144–62. 2. VERMEIREN L, DEVLIEGHERE F, VAN BEEST M, DE KRUIJF N and DEBEVERE J, ‘Developments in the active packaging of foods’, Trends Food Sci Technol, 1999 10 77–86. 3. FABECH B, HELLSTR?M T, HENRYSDOTTER G, HJULMAND-LASSEN M, NILSSON J, RU ¨ DINGER L, SIPILA ¨ INEN-MALM T, SOLLI E, SVENSSON K, THORKELSSON A ` E and TUOMAALA V, Active and intelligent food packaging – A Nordic report on legislative aspects, Copenhagen, Nordic Council of Ministers, 2000. 4. PASTORELLI S, DE LA DRUZ C, PASEIRO P, DE MEULENAER B, HUYGHEBAERT A, DE KRUIJF N, VAN BEEST M and RIJK R, ‘Chemical elucidation of the composition of some active packaging materials’, Food Addit Contam, submitted for publication. 5. DE MEULENAER B, HUYGHEBAERT A, SIPILA ¨ INEN-MALM T, HURME E, DE KRUIJF N, VAN BEEST M, RIJK R, PASEIRO P, PASTORELLI S, DE LA CRUZ C, WILDERVANCK C and BOUMA K, ‘Classification of some active and intelligent food packaging systems with regard to current EU food 492 Novel food packaging techniques packaging legislation’, Food Addit Contam, submitted for publication. 6. DE MEULENAER B, HUYGHEBAERT A, DE KRUIJF N and RIJK R, ‘On the use of agar gels as alternative food simulants to evaluate migration from selected active packaging materials’, Innovative Food Science and Emerging Technologies, submitted for publication. 7. Council Directive of 21 December 1988 on the approximation of the laws of the Member States relating to materials and articles intended to come into contact with foodstuffs. Official Journal, L040, 11/02/1989,0038- 0044. Corrigendum Official Journal, L 347, 28/11/1989, 0037. 8. Commission Directive 2002/72/EC of 6 August 2002 relating to plastic materials and articles intended to come into contact with foodstuffs (Text with EEA relevance). Official Journal, L220, 15/8/2002, 0018-0058. 9. Commission Directive of 9 June 1980 determining the symbol that may accompany materials and articles intended to come into contact with foodstuffs (80/590/EEC). Official Journal, L151, 19/06/1980, 0021-0022. 10. Council Directive 82/711/EEC of 18 October 1982 laying down the basic rules necessary for testing migration of the constituents of plastic materials and articles intended to come into contact with foodstuffs. Official Journal, L297, 23/10/1982, 0026-0030. 11. Commission Directive 93/8/EEC of 15 March 1993 amending Council Directive 82/711/EEC laying down the basic rules necessary for testing migration of constituents of plastic materials and articles intended to come into contact with foodstuffs. Official Journal, L 090, 14/04/1993, 0022– 0025. 12. Commission Directive 97/48/EC of 29 July 1997 amending for the second time Council Directive 82/711/EEC laying down the basic rules necessary for testing migration of the constituents of plastic materials and articles intended to come into contact with foodstuffs (Text with EEA relevance). Official Journal, L 222, 12/08/1997, 0010-0015,. 13. Council Directive of 19 December 1985 laying down the list of simulants to be used for testing migration of constituents of plastic materials and articles intended to come into contact with foodstuffs (85/572/EEC). Official Journal, L372, 31/12/1985, 0014-0021. 14. Commission Directive 93/10/EEC of 15 March 1993 relating to materials and articles made of regenerated cellulose film intended to come into contact with foodstuffs. Official Journal, L93, 17/04/1993, 0027-0036. 15. Commission Directive 93/111/EC of 10 December 1993, amending Directive 93/10/EEC relating to materials and articles made of regenerated cellulose film intended to come into contact with foodstuffs. Official Journal, L310 14/12/1993, 0041. 16. Council Directive of 15 October 1984 on the approximation of the laws of the Member States relating to ceramic articles intended to come into contact with foodstuffs (84/500/EC). Official Journal, L277 20/10/1984, 0012-0016. 17. Commission Directive 2002/16/EC of 20 February 2002 on the use of Legislative issues relating to active and intelligent packaging 493 certain epoxy derivatives in materials and articles intended to come into contact with foodstuffs (Text with EEA relevance). Official Journal, L 051 22/02/2002, 0027-0031. 18. Council Directive of 21 December 1988 on the approximation of the laws of the Member States concerning food additives authorized for use in foodstuffs intended for human consumption (89/107/EEC). Official Journal, L 040, 11/02/1989, 0027-0033. 19. European Parliament and Council Directive 94/34/EC of 30 June 1994 amending Directive 89/107/EEC on the approximation of the laws of Member States concerning food additives authorized for use in foodstuffs intended for human consumption. Official Journal, L 237, 10/09/1994, 0001-0002. 20. European Parliament and Council Directive No 95/2/EC of 20 February 1995 on food additives other than colours and sweeteners. Official Journal, L 061, 18/03/1995, 0001-0040. 21. Directive 2001/5/EC of the European Parliament and of the Council of 12 February 2001, amending Directive 95/2/EC on food additives other than colours and sweeteners. Official Journal, L 055, 24/02/2001, 0059-0061. 22. European Parliament and Council Directive 94/36/EC of 30 June 1994 on colours for use in foodstuffs. Official Journal, L 237, 10/09/1994, 0013- 0029. 23. European Parliament and Council Directive 94/35/EC of 30 June 1994 on sweeteners for use in foodstuffs. Official Journal, L 237, 10/09/1994, 0003-0012. 24. Directive 96/83/EC of the European Parliament and of the Council of 19 December 1996 amending Directive 94/35/EC on sweeteners for use in foodstuffs. Official Journal, L 048 , 19/02/1997, 0016-0019. 25. Council Directive of 22 June 1988 on the approximation of the laws of the member states relating to flavourings for use in foodstuffs and to source materials for their production (88/388/EEC). Official Journal, L 184, 15/ 07/1988, 0061-0066. 26. Commission Directive of 16 January 1991 completing Council Directive 88/388/EEC on the approximation of the laws of the Member States relating to flavourings for use in foodstuffs and to source materials for their production (91/71/EEC). Official Journal, L 042 , 15/02/1991, 0025- 0026. 27. Regulation (EC) No 2232/96 of the European parliament and of the Council of 28 October 1996 laying down a Community procedure for flavouring substances used or intended for use in or on foodstuffs. Official Journal, L 299, 23/11/1996, 0001-0004. 28. Commission Decision of 23 February 1999 adapting a register of flavouring substances used in or on foodstuffs drawn up in application of Regulation (EU) 2232/96 of the European parliament and of the Council of 28 October 1996 (notified under number C(1999) 399) (text with EEA relevance) (1999/217/EC). Official Journal, L 084, 27/03/1999, 494 Novel food packaging techniques 0001-0007. 29. Commission Decision of 18 July 2000 amending Decision 1999/217/EC adopting a register of flavouring substances used in or on foodstuffs (notified under document number C(2000) 1722) (Text with EEA relevance) (2000/489/EC). Official Journal, L197, 03/08/2000, 0053- 0056. 30. Directive 98/8/EC of the European Parliament and of the Council of 16 February 1998 on the placing of biocidal products on the market. Official Journal, L 123, 24/04/1998, 0001-0063. 31. Council Directive of 15 July 1991 concerning the placing of plant protection products on the market (91/414/EEC). Official Journal, L 230, 19/08/1991, 0001-0032. 32. Council Directive 93/43/EEC of 14 June 1993 on the hygiene of foodstuffs. Official Journal, L 175, 19/07/1993, 0001-0011. 33. Council Directive 92/5/EEC of 10 February 1992 amending and updating Directive 77/99/EEC on health problems affecting intra-Community trade in meat products and amending Directive 64/433/EEC. Official Journal, L 057, 02/03/1992, 0001-0026. 34. Council Directive of 21 December 1988 on the approximation of the laws of the Member States relating to quick-frozen foodstuffs for human consumption (89/108/EEC). Official Journal, L 040, 11/02/1989 0034- 0037. 35. FAO/WHO Codex Alimentarius Commission (1997). Hazard Analysis and Critical Control Point (HACCP) system and guidelines for its application. Annex to CAC/RCP 1-1969, Rev. 3 (1997). In Food Hygiene Basic Texts. Rome: Food and Agriculture Organization of the United Nations, World Health Organization. 36. European Commission, Harmonization of safety criteria for minimally processed foods, Inventory report, FAIR Concerted Action FAIR CT96- 1020. 37. Directive 2000/13/EC of the European Parliament and of the Council of 20 March 2000 on the approximation of the laws of the Member States relating to the labelling, presentation and advertising of foodstuffs. Official Journal, L 109, 06/05/2000, 0029-0042. 38. Council Directive of 19 December 1974 on the approximation of the laws of the Member States relating to the making-up by volume of certain prepackaged liquids (75/106/EEC). Official Journal, L 042, 15/02/1975, 0001-0013. 39. Council Directive of 20 January 1976 on the approximation of the laws of the Member States relating to the making-up by weight or by volume of certain prepackaged products (76/211/EEC). Official Journal, L 046, 21/ 02/1976, 0001-0011. 40. Council Directive 2001/95/EC of 3 December 2001 on general product safety (Text with EEA relevance). Official Journal, L 11, 15/01/2002, 0004-0017. Legislative issues relating to active and intelligent packaging 495 41. NEN-EN 71-1: 1998. 01/09/1998. Safety of toys – Part 1: Mechanical and physical properties. 42. Council Directive of 27 June 1967 on the approximation of laws, regulations and administrative provisions relating to the classification, packaging and labelling of dangerous substances (67/548/EEC). Official Journal, L 196, 16/08/1967, 0001-0005. 43. Council Directive of 25 June 1987 on the approximation of the laws of the Member States concerning products which, appearing to be other than they are, endanger the health or safety of consumers (87/357/EEC). Official Journal, L 192, 11/07/1987, 0049-0050. 44. European Parliament and Council Directive 94/62/EC of 20 December 1994 on packaging and packaging waste. Official Journal, L 365 , 31/12/ 1994, 0010-0023 496 Novel food packaging techniques 23.1 Introduction Food packaging is a still growing market. As a consequence, the demand to re-use post-consumer packaging materials grows as well. Recycling of packaging materials plays an increasing role in packaging, and numerous applications can already be found on the market. Ten or twenty years ago most post-consumer packaging waste was going into landfill sites or to incineration. Traditionally, only glass and paper/board were recycled into new applications. In the case of packaging plastics the situation is quite different. Only uncontaminated in-house production waste was collected, ground and recycled into the feedstream of the packaging production line without further decontamination. With increasing environmental demands, however, post-consumer plastics packaging materials have also been considered more and more for recycling into new packaging. A closed-loop recycling for packaging plastics is also supported by public pressure. The packaging and filling companies have to take responsibility for their packaging materials and environmental concerns. In many countries the consumer, government and the packaging companies want to have packaging materials with a more favourable ecobalance in the supermarkets. A more favourable ecobalance can be achieved with different approaches. One of these approaches is the re-use of recycled material in packaging. This development is driven by the recent strong increase in polyethylene terephthalate (PET) bottles used for soft drinks, water and other foodstuffs. 1 Today, many filling companies have decided to start using recycled plastics into their PET bottles in the near future. But recycling of packing plastics is also a question of recycling technology and collection of packaging waste. Today many countries have established 23 Recycling packaging materials R. Franz and F. Welle, Fraunhofer Institute for Process Engineering and Packaging, Germany collection systems for post-consumer packaging waste, like the green dot systems. Such country-wide collecting systems guarantee increasing recovery rates. Together with new developments of recycling systems and with increasing recycling capacity the way is open for some plastics for a high value recycling of packaging waste. Due to health concerns most of the recycled post-consumer plastics are going into less critical non-food applications, but in recent years there have also been efforts to recycle post-consumer plastics like PET into new food packaging applications. This changes the situation for some packaging plastics from an open-loop recycling of packaging plastics into a closed-loop recycling into new packaging materials. However, the recycling of post- consumer plastics into direct food contact application needs much more knowledge about contamination and migration than for non-food applications, in order to assess the risk to consumers’ health. Additionally a quality assurance system for post-consumer plastics should be established. 23.2 The recyclability of packaging plastics It is generally known that food contact materials are not completely inert and can interact with the filled product. 2 In particular, interactions between packaging plastics and organic chemicals deserve the highest interest in this context. Such interactions start with the time point of filling and continue during the regular usage phase of a package and even longer, in case a consumer ‘misuses’ the empty packaging by filling it with chemical formulations such as household cleaners, pesticide solutions, mineral oil or others. The extent of these interactions depends on the sorption properties and the diffusion behaviour which is specific to certain polymer types or individual plastics. These physical properties together with the contact conditions ultimately determine the potential risk of food contamination from recycled packaging plastics. In other words, taking only the polymer itself into consideration and not possible recycling technologies with their special cleaning efficiencies, etc., under given conditions the inertness of the polymer is the basic parameter which determines the possibility for closed-loop recycling of packaging plastics. The inertness of common packaging polymers decreases in the following sequence: Poly(ethylene naphthalate) (PEN), poly(ethylene terephthalate) (PET), rigid poly(vinyl chloride) (PVC) > polystyrene (PS) > high density polyethylene (HDPE), polypropylene (PP) > low density polyethylene (LDPE) In relation to this aspect, PEN, PET or rigid PVC do possess much more favourable material properties in comparison to other packaging plastics, such as polyolefins or polystyrene and are, therefore, from a migration related point of view much better suited for being reused in packaging applications. Polymers 498 Novel food packaging techniques like polystyrene and HDPE may also be introduced into closed loop recycling if the cleaning efficiency of the recycling process is high enough regarding the input concentrations of post-consumer substances. However, regarding consumers’ safety, the composition and concentration of typical substances in post-consumer plastics and the ability of the applied recycling process to remove all post-consumer substances to concentrations similar to virgin materials is of interest. The incoming concentration of post-consumer contaminants can be controlled off-line with laboratory equipment like gas chromatography or HPLC or online with detecting or sniffing devices. With help of online devices nearly a 100% control of the input materials can be established. Therefore the post- consumer material is much more under control and packaging materials with high concentrations of migratable substances, or misused bottles, can be rejected and the requirements on the cleaning efficiency of the recycling process are lower. The source control is therefore the crucial point regarding of the ‘worst- case’ scenario of the so-called challenge test (see Section 23.4.1). Recovery of packaging plastics into new packaging applications requires blending of recycled with virgin materials. In praxis today, the recyclate content of packaging materials varies from only a few per cent up to 50% recycled material in some packaging applications. Numerous studies have been carried out on the determination the material properties and the blending behaviour of recycled plastics. However, it is not the focus of this chapter to deal with blending of polymers but it needs to be stressed that the recycled material should be suitable for blending with virgin materials. Additionally, the mechanical properties of the recyclate should be not influenced in a negative way, so as to avoid potential consequences for the additive status of the recycled plastics. The average number of cycles is a function of the blend ratio and the number of recycling steps carried out. In practice the average number of cycles ranges from one to three. 3 Therefore, the material is not recycled many times and the problem of accumulation of degradation products is in most cases of no concern. An inherent problem of recycling, however, is the inhomogeneity of the recovered materials. Normally various polymer additives, lubricants, etc. are used by the different polymer manufacturers or converters in order to establish the desired properties of the packaging materials, and all different polymer additives are found as a mixture in the recyclate containing packages. Modern sorting technologies are able to provide input materials for recycling which are nearly 100% of one polymer type. Taking, in addition, the additive status into account will be a sophisticated challenge of future developments. Together with the inertness of the polymers this is one reason why recent closed-loop recycling efforts are focused on polymers which have low amounts of additives e.g. PET. However, as mentioned above, the question of recyclability is mainly influenced by the source control of the input material going into the recycling process. If the recovery system considers the manufacturer or the origin of the packaging materials, usually the additive status of the input feedstock is known. An example for this will be HDPE milk bottles collected by a deposit system (see Section 23.5.2). Recycling packaging materials 499 23.3 Improving the recyclability of plastic packaging 23.3.1 Source control The source control is the first and most important step in closed-loop recycling of packaging plastics. There must be efficient recovery or sorting processes which are able to control the input fraction going into a closed-loop recycling process. The feedstream material should have a minimum polymer type purity of 99%. Other polymers, which may interfere, have to be sorted out of the recycling stream. Also the first life of the packaging material is of interest. In general only packages previously filled with foodstuffs should be used as an input fraction for a closed-loop recycling process. However there are exceptions, e.g. for PET due to its high inertness the first packaging application is not so important. Two studies were undertaken 4,5 to determine the impact of PET materials formerly used for non-food applications. Both studies came to the same result, that due to the low diffusivity of PET packages from non-food applications could also be used as input material for bottle-to-bottle recycling. This underlines the favourite position of PET bottles for a closed loop recycling. It could be shown that deposit systems and recovery systems like curbside packaging collections with efficient sorting processes, are able to support input materials for high value recycling. However, as mentioned above, the higher the diffusivity of the polymer and, therefore, higher sorption of post-consumer substances the more important is the source control in order to reduce contamination with post-consumer substances or misused packages. The source control can be supplied by modern detecting or sniffing devices which are able to reduce the intake of undesired post-consumer substances into the recycling stream. 23.3.2 Contamination levels and frequency of misuse of recycled plastics Regarding the typical contamination of post-consumer plastics most published data are available for PET bottles and corresponding recyclates. Most of them have quantified or identified substances in post-consumer PET by using different methods. Sadler et al. 6,7 , published two studies containing data of contaminants in recycled PET. In the first study he pointed out that most compounds found in recycled PET come from PET starting materials, oligomers, flavour bases, label materials and compounds originating in base cups. Contaminants which do not fall into one of these categories are rare. In samples with high levels of contaminants the sum of all compounds was detected to be approximately 25 ppm. No single contaminant appears to be present in post-consumer PET above 1 ppm and all non-usual compounds in post-consumer PET were present below 0.1 ppm. In a second study the identity and origin of contaminants in food grade virgin and commercially washed post- consumer PET flakes were determined. A total of 18 samples of post-consumer recycled PET flakes was examined. In most cases, positive identification was possible, however, in few cases ambiguity resulted from the similarities in mass 500 Novel food packaging techniques spectra of closely related compounds. Compounds identified were classified into categories associated with their chemical nature or presumed origins, e.g. small and ethylene glycol related compounds (methanol, formic acid, acetaldehyde, acetic acid), flavour compounds (limonene), benzoic acid or related benzene dicarboxylic acid substances (benzoic and terephthalic acid and corresponding esters, benzaldehyde, phthalates), aliphatic hydrocarbons and acids as well as unexpected and miscellaneous compounds (Tinuvin, nicotine). Bayer 4 has analysed samples from five different recovery systems including PET containers from non-food applications. In these samples he identified 121 substances. The total concentration of all substances found in deposit material was 28.5 ppm. The corresponding concentrations of PET flakes coming from non-food applications were found to be 39 ppm. The key compounds identified were hexanal, benzaldehyde, limonene, methyl salicylate and 5-iso-propyl-2- methylphenol (the flavour compound carvacrol). In conventional washed flakes a maximum concentration of 18 ppm for limonene was determined. For PET flakes from non-food applications the major compound methyl salicylate was determined in a maximum concentration of 15.3 ppm. Additionally the material was analysed after a super-clean process. No peak could be detected in concentrations above the FDA threshold of regulation limit of 0.22 ppm. All three published studies mentioned above found no hints for misuse of post-consumer PET bottles e.g. for storage of household cleaners etc. This is most probably due to the fact that these studies are based only on very small amounts of different flake samples. From a statistical point of view flakes from misused bottles should be extremely rare due to high dilution with non-misused PET bottles. Therefore, these published studies are not able to detect the frequency of misuse in typical post-consumer PET flakes. In 2002 an EU project under the co-ordination of Fraunhofer IVV was finished. 8,9,10 Within this study 689 post-consumer PET flake samples from commercial washing plants were collected between 1997 and 2001. The samples are conventionally recycled deposit and curbside fractions collected in twelve European countries. In addition, 38 reprocessed pellet samples and 142 samples from super-clean recycling processes were collected. All samples were screened for post-consumer substances, and for hints of possible misuse of the PET bottles by the consumer, in order to get an overview of the quality of commercially recycled post-consumer PET. As a result the average concentrations in 689 PET flake samples for typical post-consumer compounds like limonene and acetaldehyde are 2.9 ppm and 18.6 ppm, respectively. A maximum concentration of approximately 20 ppm of limonene and 86 ppm for acetaldehyde could be determined, which is in close agreement with the above- mentioned studies. The impact of the recovery system and the country, where the post-consumer PET bottles were collected, on the nature and extent of adventitious contaminants was found not to be significant. However in three bottle flakes hints for a possible misuse of PET bottles e.g. for storage of household chemicals or fuels were found. From a statistical evaluation 0.03 to 0.04% of the PET bottles might be misused. Under consideration of the dilution Recycling packaging materials 501 of the PET flakes during washing and grinding with non-misused PET bottles average concentrations of 1.4 to 2.7 ppm for conspicuous substances from misused PET bottles were estimated from the experimental data. These concentrations can be considered as a basis for the design of challenge tests with respect to sufficiently high input concentrations of surrogates. The frequency of misuse was also detected by two other studies. Allen and Blakistone 11 indicate that hydrocarbon ‘sniffers’ for refillable PET bottles rejected between 0.3 and 1% of PET bottles as contaminated. The majority of these rejections came from PET containers with ‘exotic’ beverages and not from harmful contaminants. Therefore the part of misused bottles on the rejection in the ‘sniffer’ device is less than 0.3 to 1%. Bayer et al. 12 reported the frequency of misuse of PET bottles is one misused bottle out of 10 000 uncontaminated bottles. Both studies are in agreement with the results of the EU project. In conclusion for PET the predominating polymer unspecific contaminants are soft drink components where limonene plays a key role. PET unspecific contaminants such as phthalates are found far below 1 ppm. Misuse of PET bottles occurs only in a very low incidence and due to dilution with non- contaminated material the average concentration of substances originated from misuse are also in the lower ppm range. It should be noted here, that the given conclusions are only for PET bottles. If closed loop recycling of other packaging plastics is to be established similar studies on the input concentrations of post- consumer substances should be done. Comprehensive studies on the contamination of other polymers than PET are vary rare in the literature. Huber and Franz 13 investigated 21 reprocessed HDPE pellet samples from the bottle fraction of household waste collections from five different sources. Aim of the study was to investigate the quality of the recycled HDPE samples focusing on substances which are not present in virgin polymers. The samples are recycled with conventional washing and extruding steps without a further deep cleansing recycling process. They found that the post- consumer related substances in these different samples were the same. They identified 74 substances which occur in concentrations in the polymers above 0.5 ppm. The predominant species are ester from saturated fatty acids and phthalates, hydrocarbons, preservatives, monoterpenes and sesquiterpenes including their derivatives. Most of the substances are identified as constituents from personal hygiene products, cosmetics and cleaning agents which are sorbed into the polymer material during storage. The highest concentrations were found for limonene, diethylhexyl phthalate and the isopropyl esters of myristic and palmitic acid, which are present in the concentration range of 50 ppm to 200 ppm. Many odour compounds and preservatives are determined in concentrations of about 0.5 ppm and 10 ppm. They came to the conclusion that due to the concentration and nature of contaminants found in the investigated HDPE samples the recycled material is suitable only for non-food packaging. In a second study Huber and Franz 14 investigated a total amount 79 polymer samples (HDPE, PP, PS and PET) from controlled recollecting sources. As a 502 Novel food packaging techniques result they found limonene in nearly all polymer samples independent of the polymer type in concentrations up to 100 ppm for polyolefines (HDPE and PP) and 12 ppm and 3 ppm for PS and PET, respectively. Limonene can be considered as a marker substance for post-consumer polymers. It is interesting to note that the differences in the limonene concentration are in line with the diffusion behaviour of the polymers. In addition to limonene they found phthalates esters, alkanes, 2,6-di-tert-butyl-4-hydroxytoluene and oligomers but no hints for misuse of the bottles for storage of toxic chemicals. They concluded that most of the investigated (conventionally recycled) polymers are excluded from closed loop recycling due to the fact that in the polymers substances can be detected which are not in compliance with the European positive list system. It should be noted here that this is an inherent problem of positive lists in view of food law compliance of recycled polymers as well as virgin polymers. A threshold of regulation concept should offer a solution of assuming that a certain concentration of non-regulated compounds is of no concern for consumers’ health. 23.3.3 Recycling technology Today a considerable diversity in recycling technologies can be found, although all of them have the same objective which is to clean up post-consumer plastics. Most of them first use a water-based washing step to reduce surface contamination and to wash off dirt, labels and clues from the labels. The material is also ground to flakes during one of the first steps in the recycling process. In most cases these washing steps are combined with separating steps where different materials like polyolefines of PET are separated due to their density. It is obvious, that the cleaning efficiency of these washing processes is normally very different, depending on time, on hot or cold water-based washing or depending on the detergents added to the washing solution. However, typical washing processes are able to remove only contaminants from the surface of the polymers. 15,16 They are not able to remove organic substances which have migrated in the polymer. Therefore the purity of washed flakes is usually not suitable for closed-loop recycling. A simple remelting or re-extrusion of the washed fakes has an additional cleaning effect, 17 however the purity is usually not sufficient for reuse in the sensitive area of food packaging. So-called super-clean processes for closed-loop recycling of packaging materials therefore use further deep cleansing steps. Although there are many technologies commercially available the deep cleansing processes normally use heat and temperature, vacuum or surface treatment with chemicals for a certain time to decrease the concentration of unwanted substances in the polymers. The research on the cleaning efficiency of such super-clean recycling processes has shown that the existing recycling technologies are distinct in terms of rejection of unsuitable material, removal of contaminants and dilution with virgin material. Each of these stages in recycling uses special processes which have an effect on the quality of the finished recyclate containing packaging. Recycling packaging materials 503 23.4 Testing the safety and quality of recycled material 23.4.1 Challenge test The cleaning efficiency of super-clean processes is usually determined by challenge test. This challenge test is based on an artificial contamination of the input material going into the recycling process. Drawing up a worst-case scenario this challenge test simulates the possible misuse of the containers for the storage of household or garden chemicals in plastic containers. The first recommendations for such a challenge test are coming from the American Food and Drug Administration (FDA) 18,19 in 1992. It was a very pragmatic approach. The FDA originally suggested realistic contaminants like chloroform, diazinon, gasoline, lindane, and disodium monomethyl arsenate for use in challenge tests. However it has been shown in the past that the stability of these surrogates during recycling is in some cases not sufficient. Also the analytical methods in order to detect the surrogates are often difficult to establish and have high detection limits. It is easy to understand that the surrogates used in a challenge test should not degrade during all recycling steps. Otherwise the cleaning efficiency will be better than reality, with adverse consequences towards consumers’ safety. In the last ten years the selection of the surrogates has moved to chemicals with more model character. This development was supported by the fact that the range of chemicals available to the customers is extremely limited in practice, especially in the case of known genotoxic carcinogens. The surrogates used today in challenge tests cover the whole range of physical properties like polarity and volatility as well as the chemical nature of the compounds. Additionally, in some surrogates very aggressive chemicals towards the polymer are introduced. However, if too aggressive chemicals are used the physical properties of the polymer and the diffusion behaviour might be changed, which reduces the perception of the challenge test. Nowadays volatile chemicals like toluene, chlorobenzene, chloroform or 1,1,1-trichloroethane as well as non- volatile substances like phenyl cyclohexane, methyl stearate, tetracosane, benzophenone, methyl salicylate and methyl stearate are typically used. Of course, other substances with defined physical and chemical properties can be used for a challenge test. It should be kept in mind that such a test should challenge the recycling process in a worst-case scenario. If the resultant recyclate meets the food law requirements even under such a worst case scenario the process is able to produce recyclates suitable for reuse in packaging applications. In the last decade there have been controversial discussions between scientists, industry and authorities, in view of the worst-case character of such challenge tests. In most cases these discussions arise from the lack of information about the average contamination in the input materials for recycling. As mentioned above, the worst-case scenario depends on the concentrations of undesired substances in the post-consumer plastics as well as the frequency of misuse of plastic containers. With knowledge of contamination appropriate safety margins for each polymer type can be defined. 504 Novel food packaging techniques 23.4.2 Cleaning efficiency of conventional recycling processes Post-consumer PET which are going into packaging applications are usually recycled with super-clean recycling processes. However, these processes use conventional washing steps as well as several deep-cleansing steps in order to eliminate undesired post-consumer substances from the PET polymer matrix. Therefore the cleaning efficiency of conventional washing processes is of interest because it influences the input concentration of post-consumer substances in feedstock material going into the deep-cleansing processes. In the literature there are a few studies on the cleaning efficiency of conventional recycling processes. These processes contain washing and surface drying steps followed in some cases by remelting of the post-consumer material. Komolprasert and Lawson 15 determined the influence of NaOH concentration, mixer speed and temperature on removal of the surrogate tetracosane from spiked PET. In this study percentages of residual tetracosane in the PET flakes which were washed in small-scale experiments using 13 different conditions were determined. The results show that the tetracosane concentration in the washed flakes was 1.4 to 3.3% of the initial spiked level. As a result only mixer speed and temperature showed a significant effect on removal of the surrogate tetracosane from the PET flakes, while the effect of NaOH concentration was insignificant. The percentage of non-volatile hydrocarbon residues in washed PET flakes varies with the initial concentration. The study determined a removal of 89 to 97% of each hydrocarbon by washing. In a second study Komolprasert and Lawson 16 determined the effect of washing and drying on the removal of surrogates in spiked PET flakes as well as in spiked PET bottles. They concluded that the combination of washing and drying removes 97 to 99% of the organic surrogates from the spiked PET bottles. The copper concentration was found to be 21% of the initial concentration after washing and drying (remark: the low cleaning efficiency for the copper organic compound is most probably due to the instability of this surrogate. It reacts during recycling to CuO which cannot be removed. This behaviour shows that metal organic compounds are in general unsuitable as surrogates for challenge tests). In case of spiked PET flakes washing and drying removes more than 99% of the initial concentration of the organic surrogates. The high cleaning efficiencies of conventional washing and drying processes are most probably due high temperatures applied during the drying step and due to the fact that contaminants rarely penetrate more than a few m into the polymer surface. This is in agreement with the result that the initial concentrations of the surrogates in spiked bottles are much lower than those in flakes, because the surface area of flakes is higher than in bottles. A third study from Komolprasert et al. 17 evaluates the decontamination by remelting in a laboratory extruder. The results show that remelting can further reduce the contamination of spiked PET. However, from the data given in this paper, the amount of this reduction is very difficult to evaluate, because of the fact that the some of the applied surrogates (diazinon, malathion, metal organic copper compound) are not stable during extrusion. In addition volatile Recycling packaging materials 505 substances like toluene are almost completely removed during washing, so that an evaluation of the cleaning effect during remelting on basis of these surrogates is impossible. In conclusion, conventional washing processes are able to reduce the input concentrations of post-consumer substances in flakes. The washing process itself most probably removes only contaminants on the surface of the flakes whereas thermal drying processes are also able to decrease substance which sorbed into the flakes. Remelting processes further reduce the contamination. Due to the fact that conventional recycling processes use a wide range of parameters and equipment, a general conclusion and a quantification of the cleaning effects for washing, drying and remelting processes is not possible on basis of the above mentioned results. 23.4.3 Cleaning efficiency of super-clean processes In the last decade studies were undertaken to quantify the residual amounts of chemical substances in the material after deep-cleansing. Therefore the cleaning efficiency of super-cleaning recycling processes is well known. Additionally to the challenge test, the quality assurance of post-consumer recycle (PCR) PET is based on a feedstock control and an analytical quality assurance. Literature data about cleaning efficiencies of super-clean recycling processes are very rare. Three studies of the cleansing efficiency of super-clean recycling processes for PET are published by Franz and Welle. 20,21,22 The process investigated in the first two studies 20,21 contains the key steps: washing, re-extrusion and solid state polycondensation (SSP). The process was challenged with three different surrogate concentration levels. As a result the cleaning efficiencies for the different surrogates and contamination levels are between 94 and 99%. 20 The most challenging substance is benzophenone. The results show no significant dependency on the input concentration of the surrogates going into the process. It should be noted here, that this process was tested without a washing process. Including a conventional washing process, the cleaning efficiencies are increased to more than 99.3% even for benzophenone. 21 In the third study 22 a recycling process without solid stating was investigated. Except for benzophenone, the investigated recycling process reduces all surrogates by more than 95% for initial concentrations below 100 ppm and more than 90% for initial concentrations between 100 and 500 ppm. For that most challenging substance, benzophenone, a cleaning efficiency of approximately 77% at an initial contamination level of 294 ppm was obtained. In conclusion the determined cleaning efficiencies are lower than those of processes with solid stating. However, the specific migration of all surrogates from PET bottles made from contaminated and recycled PET was detected to be far below the migration limit of 10 ppb. 506 Novel food packaging techniques 23.4.4 Considerations on migration evaluation Migration from a given food/plastic package system is essentially influenced by kinetical (diffusion in plastic and food) as well as thermodynamic (equilibrium partitioning between plastic and food) factors. It is useful to start in migration evaluations as a worst assumption with total mass transfer scenarios based on knowledge of the starting concentration of a given migrant in the plastic. If this calculation leads to exceeding a migration limit, then it is advisable and necessary to refine the evaluation strategy and take account of partitioning and diffusion as the crucial parameters for migration. Complete scientific background and guidance on how to proceed can be found in the literature. 2 The FDA suggests that dietary exposures to contaminants from recycled food contact articles at a concentration of 0.5 ppb or less generally are of negligible risk. 18,19,23 With help of so-called consumption factors (CF) these dietary exposures can be converted into migration limits. For recycled PET for food contact use, for instance, the FDA system applies a CF = 0.05 as the currently valid consumption factor for post-consumer plastics and therefore the migration limit of PET recyclate-containing packages is 10 ppb for each individual substance. On the other hand, the migration limit can be converted into a maximum bottle wall concentration for any substance occurring in post- consumer plastics (including substances from virgin polymers). For example, for PET the maximum concentration in the PET material which correlates with 10 ppb dietary intake level is 0.22 ppm for a typical PET container at a thickness of 0.5 mm. This calculation is based on very conservative assumptions that all PET bottles are contaminated and that the contaminants are assumed to migrate completely from the bottle into the foodstuff. The contaminant limits calculated above also assume 100% recycled resin content in the finished article. It is generally known that the diffusion-controlled migration is usually much lower than the complete transfer of substances into the foodstuffs, and this especially for low diffusivity polymers like PET. Migration from virgin and post- consumer PET has been considered in numerous investigations where the low diffusion and migration rates have been reported and confirmed. 21,22,24 Therefore, diffusion models 25,26,27 provide an interesting scientific tool for a more realistic correlation between the allowed upper migration limit in the packed foodstuff and the corresponding maximum allowable concentration in the polymer. 18,19,28 A generally recognised migration model based on diffusion coefficient estimation of organic chemical substances in polymers 2 has been finished recently within the European project SMT-CT98-7513 ‘Evaluation of Migration Models in Support of Directive 90/128/EEC’. 29 Using this model the curves in Fig. 23.1 were calculated, which presents a correlation between migration into food and the corresponding maximum allowable concentrations of the surrogates in the bottle wall in dependency of the molecular weight for a PET bottle (assumption 1 l content with 600 cm 2 packaging surface). The migration or the corresponding residual concentration in the bottle wall was calculated for 95% ethanol at contact conditions of 40oC for 10 d. For most applications these scenarios are worst-case conditions overestimating the real migration situation by factors of at least 100. In Recycling packaging materials 507 view of challenge tests and particular focus on surrogates the following very conservative maximum allowable concentrations of surrogates in the bottle wall can be calculated independently of the package thickness: toluene 4.5 ppm, chlorobenzene 5.5 ppm, phenyl cyclohexane 7.5 ppm, benzophenone 8.6 ppm and methyl stearate 17 ppm. These concentrations can be considered to correlate safely with the 10 ppb migration limit for any food or simulant at test conditions of 10 days at 40oC. Hot-fill conditions are also covered by the above mentioned modelling data. Using test conditions of 1 h at 70oC followed by 10 days at 40oC, which are the usual test conditions for hot-fill testing, instead of only 10 days at 40oC the calculated migration rises only insignificantly. Going to a more severe condition, e.g. 30 min at 100oC followed by 10 d at 40oC the factor is 1,21. This shows that the migration from PET containers into food simulants (e.g. 95% ethanol as a worst case) are very low even under hot-fill conditions. 23.4.5 Sensory Test Requirements Huber and Franz investigated the sensory properties of conventionally recycled polymers (HDPE, PP, PS and PET). 14 They found in all samples the polymer specific odour found in virgin polymers. Nevertheless, all of the recycled polymers could be identified due to additional odour notes. For PET the lowest odour deviation was noticed and an increasing off-odour was perceptible from PS to PP and HDPE. However, the results are not surprising because in all investigated polymer samples flavour compounds like limonene can be found in Fig. 23.1 Correlation of migration into food and calculated maximum allowable concentrations (in ppm) of the surrogates in the bottle wall in dependency of the molecular weight for a 1 I PET bottle in 95% ethanol (10 d at 40oC). 30 508 Novel food packaging techniques significant concentrations, which are linked to sorbed compounds from the first use of the packaging materials (see Section 23.2.2). A deep cleansing of these polymers might influence the sensory properties in a positive way. However the sensory properties of recycled polymers are a crucial parameter for a closed loop recycling and should be investigated in case by case studies with the final recyclate containing packaging materials. This is due to the fact that odour threshold limits of some flavour compounds are very low and, in a few cases, below the analytical detection limits so that the results of the challenge test cannot be used for the sensory evaluation of recycled polymers. As an important consequence, to comply with the legal requirements of any legislation sufficient sensory inertness of the recycled PET product of food contact articles needs to be assured and this can only be achieved by appropriate sensory testing. Test conditions which in many cases can serve as worst case is storage of the article in direct contact with an appropriate food simulant (for instance water as a most severe test medium) for 10 days at 40oC. However, depending on the particular application modified tests may be more suitable. 23.5 Using recycled plastics in packaging Technically, recycled plastics can, in principle, be applied in direct food contact applications or protected from direct food contact by a functional barrier. From a legal point of view, there may be limitations due to different regulations in the European countries and the still missing harmonised rules for EU. In any case, the use of recycled plastic materials in packaging applications has to comply with the relevant regulations and must not be at the expense of the public health, nor should it alternate the filling’s quality. 31 In the following, practical examples of recycled plastics food packaging applications covered by a functional barrier as well as in direct food contact are described. 23.5.1 Indirect contact applications applying functional barriers In the most general understanding the concept of a functional barrier can be defined as follows: A functional barrier is a layer in the package which protects the food from external influences under the applied fill and storage conditions. In most cases the functional barrier is the food contact layer or, in complex multi-layer structures, one very close to it. This layer acts as a barrier against contamination from the packaging’s environment in general and, more specifically, from the recycled core layer or outer compartments of the package. The functional barrier efficiency must not be confused with an absolute physical barrier such as glass or metal layers. It is related to a ‘functional’ quantity in terms of mass transfer which is dependent on the technological and application-related parameters of the respective food-package system. These parameters are: Recycling packaging materials 509 ? manufacture conditions of the package ? thickness of the functional barrier layer ? type of functional barrier plastic ? molecular weight and chemical structure of penetrants (contaminants) ? concentration and mobility of contaminants in the matrix behind the functional barrier ? time period between manufacture of package and filling ? type of foodstuff, i.e. fat content, polarity etc. ? filling conditions and storage (time, temperature) of the packed foodstuffs More scientific background and guidance can be found in the published literature 31,32,33 as well as in the case studies described below. Three-layer PP cups for dairy products In 1994 a study was presented 34 where the safety in food contact use of symmetrically coextruded three-layered polypropylene (PP) cups with recycled post-consumer PP in the core layer (mass fraction 50%) and virgin food grade PP in the adjacent layers was investigated. The recycled PP, which contained about 95% PP and 5% PS, was completely under source control in the recollection system and had been used in its prior application for packaging yoghurt. The intended application for the recycled material was again packaging milk products such as yoghurt with storage for short times under refrigerated conditions. The essential working strategy in this study was to compare the recycled plastic with new, food grade plastic material of the same type. This comparison included experimentally three investigation levels: (1) compositional analysis of the raw materials (virgin versus recycled PP pellets), (2) compositional analysis of the finished food contact articles (virgin versus recycled cups) (3) migration testing on both types of cup (virgin and recycled) under regular as well as more severe test conditions. After identification and quantification of post-consumer or recycling-related potential migrants on levels (1) and (2) these compounds were used as indicator substances to be monitored in migration measurements on level (3). The major post-consumer related compound was identified as limonene, a flavour compound which can be found in many foodstuffs and also in the non- food area. In summary it turned out that none of post-consumer or recycling- related substances could be analytically detected in the food simulants (at a detection limit of 13 ppb) under prescribed migration test conditions. However, from the results obtained under more severe test conditions, it could be concluded finally that for the compound with the highest migration, limonene, the migration into a milk product will be below 1 ppb and for other post-consumer substances far below of 1 ppb. In conclusion, based on the US 510 Novel food packaging techniques FDA threshold of regulation concept 18 the intended application was con- sidered to be safe. Multi-layer PET bottles for soft drink applications In 1996 a study was published 35 in which the effectiveness of a virgin PET layer in limiting chemical migration from recycled PET was investigated. For this purpose three-layer bottles were prepared with an inner core (buried layer) of PET which was deliberately contaminated. The model contaminants used were toluene, trichloroethane, chlorobenzene, phenyl decane, benzophenone, phenyl cyclohexane and copper(II) acetylacetonate. As a result no migration was detected through a barrier of virgin PET of 186 39 m thickness into 3% acetic acid using general migration test conditions of 10 days at 40oC and also after 6 months storage at room temperature. Also migration testing with 50% and 95% ethanol as severe contact media which are relatively aggressive to PET did not lead to measurable migration rates. Consideration of diffusion models using limonene as substance for which diffusion coefficients were available, gave estimates that for a 100 m thick PET layer a breakthrough of a substance with comparable molecular weight would take place after 7.5 years or 0.8 years at room temperature or 40oC, respectively. It was concluded that an intact PET bottle layer in contact with the food represents an efficient functional barrier against migration from any possible contaminant encapsulated in a recycled PET material under normal conditions of use for soft drinks. Today, multi-layer PET soft drink bottles have received clearance for use in Austria, Belgium, Finland, France, Norway, Sweden and the United Kingdom. Studies on multi-layer PET and PET films for food packaging In another project, 36 several coextruded three-layered PET films spiked in the core layer with surrogates (toluene and chlorobenzene) and having a PET barrier layer thickness between 20 to 60 m, were systematically investigated with respect to their migration behaviour under different test and contact medium conditions. It was observed that the migration measured through the different barrier layers was predictable, and a diffusion model for predicting the functional barrier properties of layered films based on Fickian diffusion was presented. Also the effects of diffusion from the core layer to a virgin barrier layer during the coextrusion process was found necessary to be considered for reliable prediction of migration. On the basis of the presented mathematical model, maximum allowable concentrations can be established for a core layer for a given barrier thickness while still fulfilling threshold or specific migration limit requirements. In similar studies with symmetrical three-layer films spiked again in the core layer with toluene and chlorobenzene the functional barrier behaviour of high impact polystyrene (HIPS) was investigated. 27 The applied thicknesses of the HIPS barrier layer ranged higher than the above PET example and were 50 m, 100 m and 200 m. The contact medium was 50% ethanol which is a recognised medium for fatty food products for this plastic, and testing was carried out at Recycling packaging materials 511 40oC up to 76 days. From the results it was concluded that HIPS was an appropriate functional barrier under given application parameters which need to be optimised for the particular purpose. Generally, layer thicknesses from 100 m to 200 m were found to be very efficient, and this even in the case of exaggerated test conditions as applied in this study for fatty contact. When considering aqueous food products and room or cooling temperature applications, this conclusion is still much more valid and of general character. Again, as with the PET study, the contamination effect from the core layer to the virgin barrier layers during the high temperatures of the coextrusion process was investigated. For instance, for a 50 m thick HIPS layer it turned out that the same contamination effect of the food contact surface with the surrogate toluene, which is obtained after one year’s storage at room temperature, is achieved within 1 second only at the coextrusion temperature of 200oC. 23.5.2 Direct contact applications Mono-layer PET bottle for soft drink applications As mentioned before, PET is one of the most favoured candidates for closed- loop recycling. Due to higher costs of manufacturing multi-layer bottles, the bottle manufacturing and recycling companies started the development of recycling processes without a functional barrier of virgin PET. One decade later several super-clean recycling processes were established on an industrial scale. 1 In 2002, companies in Europe have built an overall recycling capacity of about 65.000 tons per year of super-clean post-consumer PET which can be used in direct food contact applications. The cleaning efficiencies of all the applied deep-cleansing recycling processes were investigated by challenge tests and the cleaning efficiencies are well known (see for example Lit. 20,21,22 ). In Europe today, the mono-layer direct food contact approach has received clearance for use in Austria, Belgium, France, Germany, The Netherlands, Norway, Sweden and Switzerland. Mono-layer HDPE bottles for fresh milk In 2002 the following project was started in Northern Ireland. 37 Milk bottles were recovered by a deposit system and were subjected to a bottle-to-bottle recycling process. Due to the recovery system the recycled HDPE was completely under source control and had been used in its prior application only for packaging fresh milk. The recovered material was recycled first by a conventional washing based recycling process and then further deep-cleansed using a super-clean process. Subsequently the recycled material was used with a content of 20 to 30% without a functional barrier. The intended application for the recycled material was again bottles for fresh milk with short time storage under refrigerated conditions. The project had several R&D phases before: after a screening of post- consumer HDPE milk bottles for compounds which are potential migrants the deep-cleansing process was evaluated and optimised. Subsequently, the 512 Novel food packaging techniques cleaning efficiency of the recycling process was determined with a challenge test. As a result only HDPE related compounds such as oligomers could be detected in the recycled polymer after deep-cleansing. In addition an online sniffing device based on so-called electronic noses was integrated into the recycling process. This sniffing device is able to detect potential migrants, such as solvents or other volatile substances, which might be introduced into the recycling process. Based on the challenge test results, upper limits for the concentration of volatile substances could be defined so that any HDPE lots with higher levels can be detected, and separated for being reused in non-food packaging areas. These higher recycling efforts over-compensated the principal lower material suitability of HDPE for closed loop recycling in comparison to PET. Another point of interest is, that the project was started in Northern Ireland at a small market scale which is under good control. The HDPE milk bottles were provided by only two bottle manufacturers, which are integrated into the project. By reading the bar code the vendors are able to separate bottles from these two manufacturing companies from other milk bottles which are rejected. Therefore, only milk bottles from bottle suppliers and filling companies which support the project are directed to the bottle-to-bottle recycling process. The recycling company, in principle, is therefore in a position to react on negative impacts of applied clues, label, colours etc. and can control its recyclate production. 23.6 Future trends For PET, a low diffusivity polymer, closed-loop recycling is now established in several countries all over the world. The HDPE study described in Section 23.5.2 shows that the combination of source control, efficient process technology and quality control using modern sniffing devices enables manufacturing companies also to re-use packaging plastics in direct food contact which have a higher diffusivity than PET. However, it must be realised that compared to PET recycling of polyolefines will always be of much more specific character i.e. limited to a certain first application and a relatively narrow and overseeable recovery system if it is intended to reuse the plastic for sensitive applications such as direct food contact. On the other hand recycling of polyolefine plastic crates into new ones for relatively insensitive applications, such as transport containers for fresh fruits or vegetables, is a less challenging issue and can therefore be dealt with in a more general way. Current and future technological improvements and further developments in recovery, sorting and recycling technologies will be an important basis for the expected increasing market shares of recycled polymers in the packaging area. Accompanied by increasing knowledge of possible post-consumer contaminant levels and further improving developments in analytical control systems, e.g. complete inline control of recyclate production, using appropriate sniffing devices, will enable the potential risk of exposure to the consumer of unwanted Recycling packaging materials 513 recycling-related compounds at the necessary low levels and at the expectable increasing use in the market place. However, the food packing market is not static. Further developments leading to more complex packaging systems, e.g. introduction of new barrier coating systems, multilayers or new plastics additives or active substances, may have an impact on closed-loop recycling which needs to considered at an early stage of the packaging developments. In the PET packaging area the introduction of so- called acetaldehyde scavengers can lead for instance to a yellowing of the recycled material, a negative optical appearance of the polymer which, however, does not pose a risk for the consumer but decreases the market value of recyclate-containing packaging materials. Therefore, in the future, closed-loop recycling will be a challenge which can only be efficiently and successfully managed by collaboration between recyclers and the packaging industry chain. 23.7 Sources of further information and advice 23.7.1 European Projects ‘Recycle Re-use’ and ‘Recyclability’ In the last decade the European Commission has supported two projects dealing with the question of recyclability and reusability of post-consumer plastics new food packaging applications. The first project AIR2-CT93-1014 3 is dealing with plastics packaging materials recovered from packaging waste. The second project FAIR CT98-4318 38 focuses on PET as the most favourable candidate plastics for direct food contact. Two other sections of the project are dealing with paper and board and recycled plastics covered with functional barriers. Both project reports provide deeper information on analytical approaches and their validation to assess the opportunity of recycling of post-consumer plastics into food packaging applications. Based on the results of the European Project FAIR CT98-4318 32 proposals for the forthcoming legislation were written and filed with the European Commission. One document is based on the results of the Europe-wide screening of post-consumer PET flakes and on migration considerations. 39 The other document gives guidance on the use of functional barriers. 33 23.7.2 US FDA Points to Consider In 1992 and 1995 the FDA published two guidelines for industry dealing with post-consumer plastics for direct food contact applications. 18,19 These guidelines provide recommendations about testing the cleaning efficiency of the investigated recycling process and the maximum content of post-consumer substances in recyclate-containing packaging materials as well as threshold limits for migration. Based on the agency’s reviews on petitions and on own research projects the FDA now provides an update of their guidelines. 5 This update integrates new knowledge, mainly for PET, of the contamination of post- consumer material and challenge tests. Especially for PET recommendations are 514 Novel food packaging techniques given for feedstock material from non-food applications, which are intended to be recycled into food packaging. The FDA also provides information about all ‘non objection letters’ on their internet homepage. 40 23.7.3 European ILSI document In 1997 an expert group under the responsibility of ILSI Europe has proposed specific guidelines on the re-use of recycled plastics in food packaging. 41 These guidelines, published in 1998, are based on the results obtained from the above- mentioned European ‘Recycle Re-use’ project. The intention of the document was to provide information for industry about the European view of closed-loop recycling of post-consumer plastics. The document gives recommendations for recycling or packaging companies, which want to introduce post-consumer plastics into food contact applications. 23.7.4 German BfR recommendations The German BfR (former BgVV) published in 2000 recommendations on the mechanical recycling of post-consumer PET for direct food contact applications. 28 This document is the result of a discussion by the German ‘Plastics Commission’ on PET bottle-to-bottle recycling. The BfR document gives recommendations for source control, challenge test and for the quality assurance of post-consumer PET intended to come into direct food contact. 23.8 References 1. K. FRITSCH, F. WELLE, Polyethylene terephthalate (PET) for packaging, Plast Europe, 2002, 92(10), 40–1. 2. O.-G. PIRINGER, A. L. BANER (Editors), Plastic Packaging Materials for Food – Barrier Function, Mass Transport, Quality Assurance and Legislation, 2000, WILEY-VCH, Weinheim, New York. 3. Final report of EU funded AIR project AIR2-CT93-1014, Programme to establish criteria to ensure the quality and safety of recycled and re-used plastics for food packaging, Brussels, December 1997. 4. F. L. BAYER, Polyethylene terephthalate (PET) recycling for food contact applications: Testing, safety and technologies – A global perspective, Food Additives and Contaminants, 2002, 19, Supplement, 111–34. 5. T. H. BEGLEY, T. P. MCNEAL, J. E. BILES, K. E. PAQUETTE, Evaluating the potential for recycling all PET bottles into new food packaging, Food Additives and Contaminants, 2002, 19, Supplement, 135–43 6. D. PIERCE, D. KING, G. SADLER, Analysis of contaminants in recycled poly(ethylene terephthalate) by thermal extraction gas chromatography – mass spectrometry, 208th American Chemical Society National Meeting. Washington DC, August 25, 1994, 458–71. Recycling packaging materials 515 7. G. D. SADLER, Recycled PET for food contact: Current status of research required for regulatory review, Proceedings: Society of Plastic Engineering Regional Technical Conference, Schaumburg, IL, USA, November 1995, 181–91. 8. R. FRANZ, Programme on the recyclability of food-packaging materials with respect to food safety considerations – Polyethylene terephthalate (PET), paper & board and plastics covered by functional barriers, Food Additives and Contaminants, 2002, 19, Supplement, 93–100. 9. F. WELLE, R. FRANZ, Typical contamination levels and analytical recognition of post-consumer PET recyclates, Congress Proceedings: EU-Project Workshop ‘Recyclability’, Varese, February 11, 2002. 10. R. FRANZ, M. MAUER, F. WELLE, European survey on post-consumer poly(ethylene terephthalate) materials to determine contamination levels and maximum consumer exposure from food packages made from recycled PET, Food Additives and Contaminants, submitted for publication. 11. B. H. ALLEN, B. A. BLAKISTONE, Assessing reclamation processes for plastics recycling, 208th American Chemical Society National Meeting. Washington DC, August 25, 1994, 418–34. 12. F. L. BAYER, D. V. MYERS, M. J. GAGE, Consideration of poly(ethylene terephthalate) recycling for food use, 208th American Chemical Society National Meeting. Washington DC, August 25, 1994, 152–60. 13. M. HUBER, R. FRANZ, Identification of migratable substances in recycled high density polyethylene collected from household waste, Journal of High Resolution Chromatography, 1997 29, 427–30. 14. M. HUBER, R. FRANZ, Studies on contamination of post-consumer plastics from controlled resources for recycling into food packaging applications, Deutsche Lebensmittel-Rundschau, 1997, 93(10), 328–31. 15. V. KOMOLPRASERT, A. LAWSON, Effects of aqueous-based washing on removal of hydrocarbons from recycled polyethylene terephthalate (PETE), Congress Proceedings ANTEC’94, San Francisco, 1994, 2906-9. 16. V. KOMOLPRASERT, A. LAWSON, Residual contaminants in recycled poly(ethylene terephthalate) – Effects of washing and drying, 208th American Chemical Society National Meeting. Washington DC, 1994, 435–44. 17. V. KOMOLPRASERT, A. R. LAWSON, A. GREGOR, Removal of contaminants from RPET by extrusion remelting, Packaging, Technology and Engineering, 1996, September, 25–31. 18. Points to consider for the use of recycled plastics in food packaging: Chemistry considerations, US Food and Drug Administration, Center for Food Safety and Applied Nutrition (HFF-410), Washington, May 1992. 19. Guidelines for the safe use of recycled plastics for food packaging applications, Plastics Recycling Task Force document, National Food Processors Association, The Society of the Plastic Industry, Inc. March 1995. 516 Novel food packaging techniques 20. R. FRANZ, M. HUBER, F. WELLE, Recycling of post-consumer poly(ethylene terephthalate) for direct food contact application – a feasibility study using a simplified challenge test, Deutsche Lebensmittel-Rundschau, 1998, 94(9), 303–8. 21. R. FRANZ, F. WELLE, Post-consumer poly(ethylene terephthalate) for direct food contact application – final proof of food law compliance, Deutsche Lebensmittel-Rundschau, 1999, 95, 424–7. 22. R. FRANZ, F. WELLE, Post-consumer poly(ethylene terephthalate) for direct food contact application – Challenge-test of an inline recycling process, Food Additives and Contaminants, 2002, 19(5), 502–11. 23. F. L. BAYER, The threshold of regulation and its application to indirect food additive contaminants in recycled plastics, Food Additives and Contaminants, 1997, 14, 661–70. 24. V. KOMOLPRASERT, A. R. LAWSON, Considerations for the reuse of poly(ethylene terephthalate) bottles in food packaging: migration study, Journal of Agricultural and Food Chemistry, 1997, 45, 444–8. 25. A. L. BANER, J. BRANDSCH, R. FRANZ, O. G. PIRINGER, The application of a predictive migration model for evaluation the compliance of plastic materials with European food regulations, Food Additives and Contaminants, 1996, 13, 587–601. 26. T. H. BEGLEY, H. C. HOLLIFIELD, Recycled polymers in food packaging: migration considerations, Food Technology, 1993, 109–12. 27. R. FRANZ, M. HUBER, O. G. PIRINGER, Presentation and experimental verification of a physico-mathematical model describing the migration across functional barrier layers into foodstuffs, Food Additives and Contaminants, 1997, 14(6–7), 627–40. 28. Use of mechanical recycled plastic made from polyethylene terephthalate (PET) for the manufacture of articles coming in contact with food, Bundesinstitut fu¨r Risikobewertung BfR, Berlin, October 2000. Also implemented into BfR Recommendation XVII. 29. O. PIRINGER, K. HINRICHS, Evaluation of Migration Models, Final Report of the EU-project contract SMT-CT98-7513, Brussels 2001. 30. R. FRANZ, unpublished results. 31. R. FRANZ, Safety assessment in modern food packaging applications, in: O.-G. Piringer, A. L. Baner, (editors), Plastic Packaging Materials for Food – Barrier Function, Mass Transport, Quality Assurance and Legislation. Wiley-VCH, Weinheim, 2000, Chapter 10.3, 336–57. 32. Final Project workshop of EU project FAIR CT98-4318, organised by the European Commission Joint Research Centre, Food Products Unit, and held on 10–11. February 2002 in Varese, Italy. A comprehensive download package of the presentations can be found at http://cpf.jrc.it/ webpack/projects.htm. 33. D. DAINELLI, A. FEIGENBAUM, Guidelines for functional barrier applications, oral presentation at the workshop given under Lit. 32 and downloadable from http://cpf.jrc.it/webpack/projects.htm. Recycling packaging materials 517 34. R. FRANZ, M. HUBER, O.-G. PIRINGER, Testing and evaluation of recycled plastics for food packaging use – possible migration through a functional barrier, Food Additives and Contaminants, 1994, 11(4), 479–96. 35. R. FRANZ, M. HUBER, O.-G. PIRINGER, A. P. DAMANT, S. M. JICKELLS, L. CASTLE, Study of functional barrier properties of multilayer recycled poly(ethylene terephthalate) bottles for soft drinks, Journal of Agricultural and Food Chemistry, 1996, 44(3), 892–7. 36. O. PIRINGER, M. HUBER, R. FRANZ, T. H. BEGLEY, T. P. MCNEAL, Migration from food packaging containing a functional barrier: mathematical and experimental evaluation, Journal of Agricultural and Food Chemistry, 1998, 46(4), 1532–8. 37. Personal Communication to the authors from Green Cycle, Armagh, Northern Ireland, internet http://www.greencycle.info. 38. Final report of EU project FAIR CT98-4318 ‘Programme on the Recyclability of Food Packaging Materials with Respect to Food Safety Considerations – Polyethylene Terephthalate (PET), Paper and Board and Plastics Covered by Functional Barriers’, Brussels, 2003. 39. R. FRANZ, F. BAYER, F. WELLE, Guidance and criteria for safe recycling of post consumer polyethylene terephthalate (PET) into new food packaging applications, Guidance document prepared within EU project FAIR CT98- 4318, submitted for publication. 40. Recycled Plastics in Food Packaging, US Food and Drug Administration, Center for Food Safety & Applied Nutrition, Office of Premarket Approval; internet: http://vm.cfsan.fda.gov/~dms/opa-recy.html. 41. Recycling of Plastics for Food Contact Use, Guidelines prepared under the responsibility of the International Life Sciences Institute (ILSI), European Packaging Material Task Force, 83 Avenue E. Mounier, B-1200 Brussels, Belgium, May 1998. 518 Novel food packaging techniques 24.1 Introduction: the problem of plastic packaging waste Polymers and plastics are typical materials of the last century and have made a tremendous growth of some hundreds of tons/year at the beginning of the 1930s to more than 150 million tons/year at the end of the 20th century with 220 million tons forecast by 2005. Western Europe will account for 19% of that amount. Today, the use of plastic in European countries is 60kg/person/year, in the US 80kg/person/year and in countries like India 2kg/person/year. 1 The basic materials used in packaging include paper, paperboard, cellophane, steel, glass, wood, textiles and plastics. Total consumption of flexible packaging grew by 2.9% per year during 1992–1997, with the strongest growth in processed food and above average growth in chilled foods, fresh foods, detergents and pet foods. Plastics allow packaging to perform many necessary tasks and provide thereby important properties such as strength and stiffness, barrier to gases, moisture, and grease, resistance to food component attack and flexibility. 2 Plastics used in food packaging must have good processability and be related to the melt flow behaviour and the thermal properties. Furthermore, these plastics should have excellent optical properties in being highly transparent (very important for the consumer) and possess good sealabilty and printing properties. In addition, legislation and consumers demand essential information about the content of the product. Compared to the total amount of waste generated in for example the EU, packaging accounts for only a small part, about 3%. Nevertheless, the actual total amount of packaging waste in Europe is still at least 61 million tons per year and this amount has a big impact regarding the waste streams produced by households. In the Netherlands the fraction of plastics in municipal waste is 24 Green plastics for food packaging J.J. de Vlieger, TNO Industrial Technology, The Netherlands nowadays 30% by volume 3 and in the US 21%. Disposal costs are high, in Europe 125 Euro per ton, in the USA 12–80 Euro per ton but in countries like Japan even 250 Euro per ton. 4 The durability of plastics is beyond dispute. Some plastics need to be durable but many plastics have only a limited life or are used only once and therefore durability is not essential. A recent governmental action against litter in the streets in The Netherlands shows a billboard with a plastic cup lying on the highway with the message that if nobody picks it up, this cup will still be there after 90 years. The persistence of these petrochemical-based materials in the environment beyond their functional life is a problem. To bring this waste disposal under control, integrated waste management practices including recycling, source reduction of packaging materials, composting of degradable wastes and incineration have to be introduced. However, these measures will not help to decrease dependency on petroleum-based products and part of the solution can perhaps be found in the development and introduction of so-called biodegradable packaging materials that will degrade naturally into harmless degradation products at the end of their life cycle. This had led in the past to some misconceptions about how these materials could help solve the problem because policy has always been strong on supporting recycling of present plastic materials. On the other hand politicians have also reacted by introducing legislation for degradability requirements and thus providing a platform for natural polymer producers to obtain a larger market share in the non-food area. Specific applications where biodegradability is required are sacks and bags that can be used for composting waste, foamed trays, cups and cutlery in the fast food sector, soluble foams for industrial packaging, film wrapping, laminated paper, foamed trays in food packaging, mulch films, nursery pots, plant labels in agricultural products and diapers and tissues in hygiene products. 5 24.2 The range of biopolymers 24.2.1 Introduction The development of biodegradable packaging alternatives has been the subject of much research and development in recent times, particularly with regard to renewable alternatives to traditional oil-derived plastics. Biopolymers, polymers synthesised by nature such as starch and polysaccharides, are an obvious alternative. However, these natural polymers on their own do not demonstrate the same material properties as traditional plastics, limiting potential applications of the technology. There are two major groups of biodegradable plastics currently entering the marketplace or positioned to enter it in the near future: polylactic acid (PLA) and starch based polymers. 6 These new polymers are truly degradable but full degradability will occur only when products made from these polymers are disposed of properly in a composting site. 520 Novel food packaging techniques 24.2.2 Lactic acid The efforts of biotechnology and agricultural industries to replace conventional plastics with plant derived alternatives have seen recently the following three approaches: converting plant sugars into plastic, producing plastic inside micro- organisms and growing plastic in corn and other crops. Cargill Dow has scaled- up the process of turning sugar into lactic acid and subsequently polymerises it into the polymer polylactic acid, NatureWorks TM PLA. Lactic acid can be produced synthetically from hydrogen cyanide and acetaldehyde or naturally from fermentation of sugars, by Lactobacillus. Fermentation offers the best route to the optically pure isomers desired for polymerisation. Condensation polymerisation of lactic acid itself generally results in low molecular weight polymers. Higher molecular weights are obtained by condensation polymerisation of lactide, the intermediate monomer. When racemic lactides are used, the result is an amorphous polymer, with a glass transition temperature of about 60oC, which is not suitable for packaging. 7 24.2.3 Polylactic acid Polylactic acid (PLA) is a polymer that behaves quite similarly to polyolefines and can be converted into plastic products by standard processing methods such as injection moulding and extrusion. It has potential for use in the packaging industry as well as hygiene applications. Currently a main obstacle is the high price of the raw material and the lack of a composting infrastructure in the European, Japanese and US markets. The current global market for lactic acid demand is 100,000 tons per annum, of which more than 75% is used in the food industry. Perhaps the biggest opportunities for PLA lie in fibres and films. For instance, worldwide demand for non-woven fabrics for hygiene application is 400,000 tons per annum. Other important market niches can be found in the agricultural industry such as crop covers and compostable bags. The polymer of choice for most packaging applications may be 90% L- lactide and 10% racemic D,L-lactide. This material is reported to be readily polymerised, easily meltprocessable and easily oriented. Its Tg is 60oC and its melting temperature is 155oC. Tensile strength of oriented polymers is reported to be 80–110Mpa with elongation at break of up to 30%. Polylactide films are reported to be very similar in appearance and properties to oriented polystyrene films. Residual lactide is not a concern since it hydrolyses to lactic acid, which occurs naturally in food and in the body. 7 Therefore, PLA polymers are designed for food contact. Cargill Dow, the largest producer of PLA polymers, has confirmed that one of their grades is GRAS (Generally Recognised As Safe), permitting its use in direct food contact with aqueous, acidic and fatty foods under 60oC and aqueous and acidic drinks served under 90oC. In Europe, lactic acid is listed as an approved monomer for food contact applications in Amendment 4 of the Monomers Directive, 96/11/EC. All PLA polymer additives have appropriate EU national regulatory status. 8 However, PLA is not yet found in large applications of food packaging today. Green plastics for food packaging 521 24.2.4 Native starch Starch is nature’s primary means of storing energy and is found in granule form in seeds, roots and tubers as well as in stems, leaves and fruits of plants. Starch is totally biodegradable in a wide variety of environments and allows the development of totally degradable products for specific market needs. The two main components of starch are polymers of glucose: amylose (MW 10 5 –10 6 ), an essentially linear molecule and amylopectin (MW 10 7 –10 9 ), a highly branched molecule. Amylopectin is the major component of starch and may be considered as one of the largest naturally occurring macromolecules. Starch granules are semi-crystalline, with crystallinity varying from 15 to 45% depending on the source. The term ‘native starch’ is mostly used for industrially extracted starch. It is an inexpensive (< 0.5 Euro/kg) and abundant product, available from potato, maize, wheat and tapioca. 9 24.2.5 Thermoplastic starch Thermoplastic starch (TPS) or destructurised starch (DS) is a homogeneous thermoplastic substance made from native starch by swelling in a solvent (plasticiser) and a consecutive ‘extrusion’ treatment consisting of a combined kneading and heating process. Due to the destructurisation treatment, the starch undergoes a thermo-mechanical transformation from the semi-crystalline starch granules into a homogeneous amorphous polymeric material. Water and glycerol are mainly used as plasticisers, with glycerol having a less plasticising effect in TPS compared to water, which plays a dominant role with respect to the properties of thermoplastic starch. 24.2.6 Water resistance of starch-based products Thermoplastic starch behaves as a common thermoplastic polymer and can be processed as a traditional plastic. TPS shows a very low permeability for oxygen (43cm 3 /m 2 /min/bar compared to 1880cm 3 /m 2 /min/bar of LDPE) which makes this material very suitable for many packaging applications. In contrast, the permeability of TPS for water vapour is very high (4708cm 3 /m 2 compared to 0.7cm 3 /m 2 of LDPE). This sensitivity to humidity (highly hydrophilic) and the quick ageing due to water evaporation from the matrix makes thermoplastic starch as such unsuitable for most applications. Due to this drawback there are no products available at the moment made from pure thermoplastic starch, which are form-stable (or even hydrophobic) in a wet atmosphere and mechanically stable over a sufficiently long period of time. Producers of starch-based products overcome this problem by blending the thermoplastic starch with hydrophobic synthetic polymers (biodegradable polyesters) or by the production of more hydrophobic TPS derivatives (starch ester). Unfortunately, all theses production processes make the starch-based products rather expensive in comparison to the common plastic alternatives. 522 Novel food packaging techniques New concepts are required to solve the intrinsic problem of the hydrophilicity and mechanical instability of starch-based bioplastics without too much added cost. 9 24.2.7 Polyhydroxyalkanoates An industrial fermentation process in which microorganisms converted plant sugars into polyhydroxyalkanoates was developed by ICI, later Zeneca. Almost all living organisms may accumulate energy storage materials (e.g. glycogen in muscles and in livers, starch in plants and fatty compounds in all higher organisms) whereby polyhydroxyalkanoates (PHAs), as polyesters, represent the group of energy storage materials (e.g. carbon source that is exclusively found among bacteria). Generally PHAs are thermoplastic, water-insoluble biopolyesters of alkanoic acids, containing a hydroxyl group and at least one functional group to the carboxyl group. The FDA approved Biopol, the PHA produced by Monsanto who acquired the technology from Zeneca, as a food contact material. Important aspects were the biopolymer itself and the presence of breakdown products as crotonic acid. Also the incorporation of fermentation by-products – the microorganism Ralstonia eutrophus is not food grade – was of major concern. Other types of PHAs have not been approved for food contact applications yet. 10 Although its water-resistant properties give it a cutting edge in food packaging compared to other bioplastics, the plastic turned out to cost substantially more than its fossil fuel-based counterparts and offered no performance advantages other than biodegradability. 11 29.2.8 Synthetic polyesters These (aliphatic) polyesters are formed by polycondensation of glycols and dicarboxylic acids. They have tensile and tear strengths comparable to low density polyethylene and can be coextruded and readily heat-sealed. They can be processed into blown or extruded films, foams and injection moulded products and used in refuse and compost bags and cosmetic and beverage bottles. Due to their high price, aliphatic polyesters are used only in combination with starch. When tested, starch-polyester blends show in all cases an important decrease in water sensitivity whatever the thermoplastic starch and polyester type and content but for thermoforming applications such blends cannot provide sufficient stiffness due to the intrinsic softness of the polyester. 12, 13, 14 24.2.9 Polycaprolactone and polyvinylalcohol Polycaprolactone is made from synthetic (petroleum) sources, and has seen only limited use, apart from being used in starch-blends because of its low glass transition temperature of 60oC and melting temperature of 60oC. Another polymer being used in packaging applications is polyvinylalcohol (PVOH), although its biodegradability is disputed. Some polymers like PVOH Green plastics for food packaging 523 and starch are so water sensitive that they can in fact be water soluble. The most widely used water soluble polymer PVOH is prepared by hydrolysis of polyvinylacetate. Its water solubility can be adjusted to render it soluble in both hot and cold water or in hot water only. Control of the degree of hydrolysis can give control over the water solubility of the resulting resin. PVOH is not used as food packaging but in unit doses for agricultural chemicals, dyes and pigments, as well as water-soluble laundry bags for hospitals and detergent pouches. 7 24.3 Developing novel biodegradable materials 24.3.1 Introduction One of the major problems connected with the use of most of the natural polymers, especially of carbohydrates, is their high water permeability and associated swelling behaviour in contact with water. All this contributes to a considerable loss of mechanical properties, which prohibits straightforward use in most applications. Because of the hydrophilic and low mechanical properties of starch the property profile of these materials is insufficient for advanced applications like food packaging. The few applications for just thermoplastic starch, which do not involve the use of polymeric substances to form blends, are packaging chips, packaging for capsules and as packaging for food products (e.g. separate layers in boxes of chocolates) but never in direct contact with food. Their hydrophilic character, their reduced processability (with respect to polyolefines), and their insufficient mechanical properties represent particular drawbacks in this respect. Special processing or after-treatment procedures are necessary to sustain an acceptable product quality. As indicated before, presently applied methods for decreasing the hydrophility and increasing and stabilising the mechanical properties are blending with different, hydrophobic, biodegradable synthetic polymers (polyesters) and the application of hydrophobic coating(s). One recent new technology involves the application of the nano-composite concept that has proven to be a promising option. 9 24.3.2 Barrier effect of nano clay particles in a biopolymer matrix The incorporation of nano-clay sheets into biopolymers has a large positive effect on the water sensitivity and related stability problems of bioplastic products. The nature of this positive effect lies in the fact that clay particles act as barrier elements since the highly crystalline silicate sheets are essentially non- permeable even for small gas molecules like oxygen or water. This has a large effect on the migration speed of both incoming molecules (water or gases) as well as for molecules that tend to migrate out of the biopolymer, like the water used as a plasticiser in TPS. In other words, nano-composite materials with well- dispersed nano-scaled barrier elements will not only show increased mechanical properties but also an increased long-time stability of these properties and a related reduction of ageing effects. 524 Novel food packaging techniques In order to achieve the final clay-starch nano-composite material, a ‘clay modification’ and an ‘extrusion’ processing step can be distinguished, which are described below. For the preparation of nano-composite materials consisting of starch and clay, the use of special compatibilising agents (modifier) between the two basic materials is necessary as depicted in Fig. 24.1. Layered silicates are characterised by a periodic stacking of mineral sheets with a weak interaction between the layers and a strong interaction within the layer. The space between the layers is occupied by cations. By cation exchange reactions between the clay and organic cations (such as alkyl ammonium salts) the layered silicate can be transformed into organically modified clay. The inter layer distance will increase by using voluminous modifiers. If this modifier is compatible with starch as well, a homogeneously and nanoscaled distribution (exfoliation) of the clay sheets can be effected in the polymer matrix. The modified clay can be analysed by X-ray investigation (XRD) to determine the inter-layer distance. The pure clay shows an interlayer distance of 1.26nm. It has been proven by XRD analysis that most of the layers are indeed ‘swollen’ after the modification reaction. The interlayer distance changes to 2.34nm – an increase of nearly 100% compared to the pure clay. 24.3.3 Extrusion The starch and the modified clay are mixed at temperatures above the softening point of the polymer by polymer melt processing (extrusion). At these temperatures the polymer melt intercalates. The success of the polymer intercalation depends on the modification of the clay, on the degree of increased interlayer distance and on the interaction between the modifier and the matrix material. A full destructurisation is needed for a successful polymer melt process of starch. Therefore, it is very important to find the optimal starch/clay/ plasticiser content, the most effective geometry of the screws and the right temperature profile within the extruder. 24.3.4 Properties of the starch-clay nanocomposites A homogeneous incorporation of clay particles into a starch matrix on a true nano scale has proved to be possible. The addition of clay during processing supports and intensifies the destructuring process of starch, providing a means of easier processing. The obtained starch/clay nanocomposite films show a very strong decrease in hydrophilicity. The stiffness, the strength and the toughness Fig. 24.1 Example of possible modifiers for starch-clay nano-composites and requirements for clay modification. Green plastics for food packaging 525 of the nanocomposite material are improved and can be adjusted by varying the water content. Clay will decrease the water permeability to some extent (maximal with a factor 2). Clay will reinforce the starch blends only when it is fully exfoliated. Hot pressed films made out from material indeed showed a great advantage compared to films made from pure thermoplastic starch. Ordinary TPS evaporates water very quickly upon ageing. Figure 24.2a shows a photograph of a hot pressed film of pure thermoplastic starch (after ageing the granulates for three hours at room temperature following the extrusion step). The apparent morphology indicates that it is not possible to form a true film any more. In contrast Fig. 24.2b shows a hot pressed film of a starch/clay nano-composite. Transparent and homogeneous films can be formed which show an increased mechanical stability and toughness as well. 24.4 Legislative issues It is important to remark that biodegradability and compostability are different concepts. 2 While biodegradation may take place as a result of the disposal of a material in landfills, composting usually requires a pre-treatment of municipal solid waste; it is necessary in fact to remove all bulky non-compostable items before beginning the composting process, separating organic from inorganic waste. Moreover, before composting other steps are necessary: particle size reduction, magnetic removal of metals, moisture addition and mixing. Under ideal conditions the decomposition of organic material can take 30 to 60 days. International Standards Research (ISR) at the request of ASTM studied the performance of biodegradable plastics in full-sized composting facilities and under laboratory conditions. The ISR work determined that plastics needed to meet three criteria to be compostable. According to this standard ASTM D6400 they must be able to: 1. demonstrate inherent biodegradability at a rate and degree similar to natural biodegradable polymers 2. disintegrate during active composting, so that there are no visible, distinguishable pieces found on the screens 3. have no ecotoxicity – nor impact the ability of the resultant compost to support microbial and plant growth. 15 A standard world-wide definition for biodegradable plastics has not been established, nevertheless all the definitions already in place (ASTM, CEN, ISO) correlate the degradability of a material to a specific disposal environment and to a specific standard test method which simulates this environment in a time period which determines its classification. The European Parliament on 20 December 1994 adopted a directive (94/62 EC) in order to harmonise national measures concerning the management of packaging and packaging waste, to provide a high level of environmental protection and to ensure the functioning of the internal 526 Novel food packaging techniques market. In the 94/62 EC Directive a very brief part is dedicated to compostable and biodegradable materials. In item three, ‘compostability’ is defined as organic recycling and it is pointed out that compostability can take place only under controlled conditions and not in landfills. Moreover, ‘biodegradable packaging’ is Fig. 24.2 Compression moulded films of a) pure TPS granulate and b) starch/clay nano- composite granulate Green plastics for food packaging 527 defined as a material that must be capable of physical, chemical, thermal and/or biological degradation such that this material used as compost ultimately decomposes completely into carbon dioxide and water. 2 According to European directive No. 94/62 the producer or importer of packaging is responsible for the recovery of a substantial fraction of the annual amount of packaging it produces in the market. It states that at least 65% must be recovered, at least 45% must be recovered by material recycling and at least 15% of each packaging material must be recycled. The term recovery denotes the sum of recycling (material recovery), incineration (energy recovery) and composting (organic recovery). Furthermore, the directive prohibits packaging that does not fulfil the essential requirements. For products to be designed to be compostable the requirement is that ‘they should be of such a biodegradable nature that it does not hinder the source-separated collection of biowaste, nor the composting activities in which it will be treated’. A draft standard, prEN 13432, has been made with requirements for compostable products. According to this standard, the following criteria are relevant for a compostable product. 16 1. The individual packaging components shall be completely biodegradable. 2. The total product shall disintegrate completely during a composting process. 3. The addition of the product to the biowaste shall not have negative effects on the composting process. 4. The addition of the product to the biowaste shall not have negative effects on the quality of the final compost. To demonstrate biodegradability, it is possible to use several internationally accepted standard methods for determining the biodegradability of organic compounds. Both aquatic tests and tests with high solids environments are allowed, although tests under controlled composting conditions are preferred. Evaluation criteria follow. 1. For a packaging material or the constituents of a packaging material which consists of only one polymer (homo-polymer or random copolymer) without any additives, the degree of biodegradation based on carbon dioxide release or oxygen consumption shall be more than 60% of the theoretical value. 2. For a packaging material or the constituents of a packaging material comprised of different components (polymer blends), or block copolymers and after addition of low molecular additives, the degree of biodegradation based on carbon dioxide release or oxygen consumption shall be more than 90% of the theoretical value. 3. The period of application of the test methods shall be a maximum of six months Unless technically impossible, the packaging, packaging materials or packaging component shall be tested for disintegration in the form in which it will 528 Novel food packaging techniques ultimately be used. In practice, packaging materials are tested and from this it is concluded that a complete packaging will be disintegrated if all its materials are capable of disintegration. A complete packaging should, however, be tested in cases where a direct conclusion is not possible, e.g., if two or more packaging materials are firmly joined together forming a fixed multi-layer structure. Due to the nature and analytical condition of the disintegration test, the test results cannot differentiate between biodegradation and biotic disintegration but they are required to demonstrate that a sufficient disintegration of the test materials is achieved within the specified treatment time of biowaste. By combining these observations with the information obtained from the laboratory tests it can be concluded whether a test material is sufficiently biodegradable under the known conditions of biological waste treatment. Food Contact Materials are all materials and articles intended to come into contact with foodstuffs, including not only packaging materials but also cutlery, dishes, processing machines, containers, etc. 17 The term also includes materials and articles that are in contact with water intended for human consumption, but it does not cover fixed public or private water supply equipment. The harmonisation at EU level of the legislation on Food Contact Materials fulfils two essential goals: the protection of the health of the consumer and the removal of technical barriers to trade. Food contact materials shall be safe and shall not transfer their components into the foodstuff in unacceptable quantities. The transfer of constituents of the food contact materials into the food is called migration. To ensure the protection of the health of the consumer and to avoid adulteration of the foodstuff two types of migration limits have been established in the area of plastic materials: 18 an overall migration limit of 60mg (of substances)/ kg (of foodstuff or food simulants) that applies to all substances that can migrate from the food contact material to the foodstuff and a specific migration limit (SML) which applies to individual authorised substances and is fixed on the basis of the toxicological evaluation of the substance. The SML is generally established according to the acceptable daily intake or the tolerable daily intake set by the Scientific Committee on Food. To set the limit, it is assumed that, every day throughout his/her lifetime, a person of 60kg eats 1kg of food packed in plastics containing the relevant substance at the maximum permitted quantity. 24.5 Current applications 24.5.1 Introduction Despite the problems still encountered in properties and production of biopolymers, biodegradable food packaging products enter the market because of supermarkets being increasingly tricked by the marketing effect of a green image. Novamont has begun to supply Tesco with nets for fruits and bags to Swiss and German supermarkets. Albert Heijn in The Netherlands uses biodegradable packages from Natura Verpackung while Sainsbury in the UK is doing composting trials for food waste at 75 of its stores, using Mater-Bi bags. Green plastics for food packaging 529 Table 24.1 gives some properties of polymers used in packaging materials. 19 Among the biodegradable polymers PLA seems to be the polymer that can compete in terms of mechanical properties with conventional polymers. The drawback here is the low Tg of PLA. 20 The main players in the biodegradable polymer market are shown in Table 4.2. Despite the slow entry into of use of biodegradables in food packaging, some trends are visibly shifting towards sustainable chemistry and green plastics being applied in niche markets. Most of the efforts these days seem to be focused on foamed products for food packaging. 24.5.2 Starch based foams in food packaging The use of foamed polymer packaging, for example, polystyrene (PS) clamshells, by prominent users such as McDonald’s Restaurants has recently decreased significantly because of perceived environmental disadvantages. Table 24.1 Properties of polymers used as packaging materials Polymer Tensile strength Tensile modulus Max. use MPa GPa temperature oC LDPE 6.2–17.2 0.14–0.19 65 HDPE 20–37.2 121 PET 68.9 2.8–4.1 204 PS 41.3–51.7 3.1 78 PA 6 62–82.7 1.2–2.8 – PP 33–37.9 1.1–1.5 121 PLA 40–60 3–4 50–60 Table 24.2 Main players in biodegradable polymers and their trade names Material Supplier Trade name Starch based Novamont MaterBi Starch based Biotec Bioplast Thermoplastic starch Avebe Paragon Thermoplastic starch National Starch Ecofoam (Novamont licensee) Envirofil Polylactide/PLA Cargill Dow Nature Works PLA Polylactide/PLA Mitsui Lacea Polylactide/PLA Hycail Polylactide/PLA Galactic Galactic (Co)polyester BASF Ecoflex (Co)polyester Eastman Chemical Eastar Bio (Co)polyester Du Pont Biomax (Co)polyester Showa Highpolymer Bionolle Polycaprolactone Union Carbide Tone polymer Polycaprolactone Solvay CAPA 530 Novel food packaging techniques Polystyrene is derived from non-renewable resources, is non-degradable and for its processing blowing agents were used in the past that contributed to the depletion of the ozone layer. Paper-based products have a more favourable environmental perception but do not share the mechanical properties of polystyrene foams. It is well known that starch, containing sufficient moisture, can provide stable foams. A step forward has been the introduction recently by Novamont of a new foamed tray based on starch particularly for the ‘McDonalds’ type of applications. 21 Apack has introduced another tray made from a baked starch formulation that has a coating of EastarBio aliphatic-aromatic copolyester. Sainsbury, a leading retailer in the UK, has been packaging its organic fruit and vegetables in these starch-based materials by Apack. 22 Paperfoam has patented Paperfoam that is produced from a viscous suspension containing starch, cellulose fibres and water. The suspension is injected into the mould. Due to the mould’s temperature (c. 200oC) the starch granulate gelatinises and the water evaporates. The manufacturing cycle bakes from five seconds to two minutes, depending on wall thickness, from starch, natural fibres and water using an energy-efficient, one-step production technology. It can be recycled with paper and is biodegradable. Paperfoam combines a foamed inner structure with a smooth outer face and is applicable for a wide variety of uses. At present Paperfoam is used in the packaging of hand- held electronic consumer goods, such as telephones, but not yet in food packaging. 23 Other types of foamed products at different stages of development are blends of starch with poly(vinyl alcohol-co-40%-ethylene), PVOH-40, a degradable, water resistant polymer that can be processed into viable alternatives to PS foam packages via wafer baking technology, extrusion, or expanded-bead moulding 24 and starch-based dough made by a baking process for various food containers. 25 Although one of the most versatile technologies for the production of starch- based foam is via this type of baking process where a starch dough is heated under pressure to form a moulded foam product, these starch products are moisture sensitive and have poor mechanical properties. Both of these attributes can be improved by the inclusion of fibres and/or fillers in the dough formulation. The resulting products are starch-based foam composites with mechanical and thermal properties rivalling those of polystyrene. 26 24.5.3 PHA in food packaging PHA properties show that it might be a very good alternative for conventional polymers in food contact packaging. However, when Monsanto bought the Biopol process in 1995 profitability still remained elusive. 11 The approach with the most potential was to grow PHA in plants, modifying the genetic make-up of the crop so that it could synthesise plastic as it grew and eliminate the fermentation process. However, it was found that producing one kilogram of PHA from genetically modified corn plants would require about 300% more Green plastics for food packaging 531 energy than the 29 megajoules needed to manufacture 1kg of fossil-fuel-based polyethylene. This finding prompted Monsanto to terminate this method of producing PHA. The Biopol assets were obtained by Metabolix but food packaging is not a product line they intend to focus on in future. Proctor and Gamble together with Kaneka Corporation are working on a new development in PHA production but this product might not become available in large quantities until 2005. 24.5.4 PLA in food packaging With PLA it is a similar story in terms of energy balance to PHA when one looks at the production site of Cargill Dow with its Nature Works TM PLA in Blair, Nebraska. The Blair plant with a capacity of 140 000 metric tons per year produces 1kg PLA with 56 megajoules of energy. However, in principle PLA processes can require between 20–50% fewer fossil resources than making plastics from oil but it is still significantly more energy intensive than most petrochemical processes. Packaging solutions from Nature Works can be extruded, thermoformed and blow moulded, unlike other traditional products, such as paper. For packaging they have two film grades and one grade for thermoforming. The film grades are designed for applications like candy twistwrap and for laminations for packaging such as flavoured crewels, coffee packs and pet foods because of the additional advantageous properties such as the barrier to flavour and grease and superior oil resistance. The potential applications of thermoformed products within packaging is multifold, dairy containers, food service ware, transparent food containers, blister packs and cold drink cups. PLA polymer has been shown to biodegrade similarly to paper under simulated composting conditions (ASTM D5338, 58oC). Degradation of PLA packaging depends both on exposure conditions and on amount and type of plasticiser. Sainsbury would like to use PLA but will not do this because of the lactic acid coming from GM crops. 21 The consumer might not accept this at the moment although the GM label is destroyed at the fermenting stage. Much of the PLA of Cargill Dow is for fibre applications but the company is already working with many leading European packaging converters, including Trespaphan on oriented PLA films, Klo¨cknes pentaplast on thermoformed trays and lids, and Autobar on thermoformed dairy pots. Food retailers are also increasingly involved. 24.5.5 Proteins in food packaging Proteins have long and empirically been used to make biodegradable, renewable, and/or edible packaging materials. Numerous vegetable proteins (corn zein, wheat gluten, soy proteins) and animal proteins (milk proteins, collagen, gelatine, keratin, myofibrillar proteins) are commonly used. Although protein materials have been studied extensively 27 a breakthrough is not yet imminent although some of the properties have increased extensively recently. Protein 532 Novel food packaging techniques materials can be processed into transparent and water-resistant films by casting or thermo-forming. In packaging, collagen sausage casings are the best known of the commercial applications. 28, 29 24.6 Future trends When one looks at the present market for biodegradable food packaging materials then that market is still virtually non-existent compared to any conventional plastics used in food packaging. The reason for this is the high price, the sometimes inferior cost/performance relation and the fact that still only a few materials have received FDA approval. Since 2001 the market for biodegradable/compostable products has definitely been growing after remaining at the same level of 20,000 tons worldwide for the last five years and although few in number, new products for food packaging have been introduced since. 24.7 References 1. JOGDAND S N, Welcome to the world of eco-friendly plastics, www.members.rediff.com, 1999 . 2. AVELLA M, BONADIES E, MARTUSSCELLI E, RIMEDIO R, ‘European current standardization for plastic packaging recoverable through composting and biodegradation’, Polymer Testing, 2001, 20, 517–521. 3. www.rivm.nl/mieucompendium: C6.6 Hoeveelheid kunststoffen en PVC in huishoudelijk restafval. 4. GRUBER P ‘Sustainable design of polymers and materials’, Abstracts, 6th International Scientific Workshop on Biodegradable Polymers and Plastics, Honolulu, Hawaii, 2000. 5. BASTIOLI C, ‘Global status of the production of biobased packaging materials’, Conference proceedings The Food Biopack Conference, Copenhagen, August 27–29, edited by C J Weber, 2–7, 2000. 6. BILBY G D, ‘Degradable polymers’, www.angelfire.com, 2000. 7. SELKE S, ‘Biodegradation and packaging’ (2nd edn), Pira International Reviews, 2000. 8. CARGILL DOW LLC, Product information, published June, 2000. 9. FISCHER S, VLIEGER J J, DE KOCK T, BATENBURG L-, FISCHER H, ‘Green’ nano- composite materials – new possibilities for bioplastics’ Materialen, 2000, 16, 3–12. 10. WEUSTHUIS R A, WALLE G A M, VAN DER EGGINK G, ‘Potential of PHA based packaging materials for the food industry’, Conference proceedings The Food Biopack Conference, Copenhagen, August 27–29, edited by C J Weber, 24–7, 2000. 11. GERNGROSS T U, SLATER S C, ‘How green are green plastics’, Scientific Green plastics for food packaging 533 American, feature article of August isssue, 2000. 12. AVE ′ ROUS L, FAUCONNIER N, MORO L, FRINGANT C, Blends of thermoplastic starch and polyesteramide: Processing and properties, J. Appl. Polym. Sci., 1999, 76, 1117. 13. AVE ′ ROUS L, MORO L, DOLE P, FRINGANT C, ‘Properties of thermoplastic blends: Starch-Polycaprolactone’, Polymer, 1999, 41, 4157. 14. AVE ′ ROUS L, FRINGANT C, to be published. 15. NARAYAN R, ‘The scientific rationale behind biodegradable/compostable standards’, Abstracts 6th International Scientific Workshop on Biodegradable Polymers and Plastics, Honolulu, Hawaii, 2000. 16. ZEE M VAN DER, ‘Compostable products-Legislation standards and future policy’, Green-Tech Newsletter April 1999, 2, 2, I. 17. LEBARON P C, WANG Z, PINNAVIA T J, ‘Polymer-layered silicate nanocomposites: an overview’, Applied Clay Science, 1999, 15, 11–29. 18. Final report Bionanopack project 1999-2001, FAIR CT98-4416, Co- ordinator J J de Vlieger, 2002. 19. BRODY A L, ‘Packaging materials’, Encyclopedia of Polymer Science and Engineering, 1987, 10, 684–710. 20. SO ¨ DERGA ? RD A, ‘Lactic acid polymers for packaging materials for the food industry’, Conference proceedings The Food Biopack Conference, Copenhagen, August 27–29, edited by C J Weber, 19–23, 2000. 21. Modern Plastics International, December 2001, 44. 22. European Plastic News, January 2002, 21. 23. Green-Tech Newsletter 2000, vol. 3, no 1, 4 Paperfoam, www.paper foam.nl. 24. ORTS W, NOBES G A R, GLENN G M, GRAY G M, HANSEN L U, HARPER M V, ‘Blends of starch with poly(vinyl alcohol)/ethylene copolymers for use in foam containers’, Abstracts 6th International Scientific Workshop on Biodegradable Polymers and Plastics, Honolulu, Hawaii, 2000. 25. GLENN G M, NOBES G A R, GRAY G M, ‘Insitu laminating process for baked starch based foams’, Abstracts 6th International Scientific Workshop on Biodegradable Polymers and Plastics, Honolulu, Hawaii, 2000. 26. NOBES G A R, ORTS W J, GLENN G M, ‘Use and effeects of agricultural fibers and fillers in baked starch-based foam composites’, Abstracts, 6th International Scientific Workshop on Biodegradable Polymers and Plastics, Honolulu, Hawaii, 2000. 27. GUILBERT S, ‘Potential of the protein based biomaterials for the food industry’, Conference proceedings The Food Biopack Conference, Copenhagen, August 27–29, edited by C.J. Weber, 13–18, 2000. 28. GUILBERT S, CUQ B, GONTARD N, ‘Recent innovations in edible and/or biodegradable packaging’, Food Additives and Contaminants 14, 2000, 6, 741–751. 29. KROCHTA J M, MUKDER-JOHNSTON C DE, ‘Edible and biodegradable polymer films: challenges and opportunities’, Food Technol., 1997, 51, 61–73 534 Novel food packaging techniques ‘All engineering, manufacturing, quality and sales efforts are wasted if your transport packaging fails and your customer receives a damaged product’ (ISTA). 1 25.1 Introduction: the supply chain for perishable foods Food is a perishable product. It is temperature-, moisture-, and time-sensitive, compared to books, automobile parts, and clothes, however they are shipped globally. The present systems for improving logistics, ordering and networks may cause the special nature of food to be ignored. The new IT systems are first applied to expensive, valuable products, not to commodity products, such as food. Then the commodity products must adapt to the systems, which exist even if the producers have not taken part in the development work. 25.1.1 Growth seasons and specialities in different areas of the world In many parts of the world there is only one yearly growing season yielding only one or two crops in a year. However, consumers prefer to eat both fresh produce and the specialities of specific areas the year round. This means that foodstuffs may be transported to the other side of the world. Some foodstuffs (canned food, aseptic packages, dried food) can be stored at room temperature. They are not sensitive to small temperature changes if they have been correctly packed. The quality and safety of frozen, chilled, and fresh food tolerates only a very narrow temperature range. Also chilled and fresh food has a limited shelf-life. An average employee in the food industry knows these 25 Integrating intelligent packaging, storage and distribution T. Ja¨rvi-Ka¨a¨ria¨inen, Association of Packaging Technology and Research, Finland facts very well, but there are several steps during transportation where one has no or very limited knowledge of the special requirements or needs of perishable products (harbours, airports, transport terminals). Also, a consumer may purchase products and expose them to too high temperatures or otherwise wrong storage conditions before they are eaten. As an example, let us look at the shipment of bananas to Finland where they are everyday commodities throughout the year. What follows are the stages on the route of bananas from tree to table. ? A half-ripe banana cluster is cut from a banana tree. ? It is lifted to a hook of a cableway. ? The cableway transports the banana cluster to the packaging area. ? The banana cluster is rinsed. ? The washed cluster is cut into smaller bunches, usually of about five bananas each. ? Cut bananas are washed. ? Bananas are lifted into a plastic tray, each tray containing about 18kg of bananas. ? The plastic tray is transported to the weighing station. ? Weighed bananas are sprayed with a biocide. ? Banana groups are brand labelled. ? Bananas are moved from the trays into transportation boxes. ? Boxes are stamped with packing date and location. ? Boxes are lifted on a pallet. ? Pallet loads are transferred to containers. ? Containers are transported to the harbour. ? Containers are lifted to a ship. ? Banana containers are monitored for temperature during the sea trip, which takes about two weeks. ? Containers are unloaded from the ship in Sweden. ? Banana pallet loads are transported to the ship terminal. ? The temperature of the bananas is checked. ? Banana pallet loads are loaded onto a lorry. ? The lorry drives onboard a ship sailing to Finland. ? Second sea voyage. ? The lorry drives the bananas to a building where the bananas are allowed to ripen. ? Bananas and their temperature are checked on arrival. ? Bananas are moved into a maturing room in order to ripen. ? During the ripening process, which takes about six days, the bananas are checked daily for their temperature and degree of ripeness. ? After ripening the bananas are transferred to a collection point. ? There the banana boxes are lifted either onto a trolley or onto a pallet. ? The full trolley or the pallet load is transported to the right gate on the shipping area. 536 Novel food packaging techniques ? The driver brings the trolley or the pallet to his truck. ? Bananas are transported to the shop. ? The driver moves the trolley to the inspection area of the shop. ? The shopkeeper checks and accepts the product. ? Bananas are moved to the storage area of the shop. ? Depending on sales the products are put on sale. ? The boxes are opened and the bananas are put on display. ? A consumer chooses some bananas and packs them into a bag ? The bananas are weighed. ? A price label is attached to the bag. ? The customer goes to the till. ? Customer puts the product on the cashier line. ? The scanner reads the price and gives the storekeeper information on the amount of bananas sold. ? The customer packs the products into a carrier bag and takes them home (Leppa¨aho, 2002). 2 The above list shows that bananas were exposed to several different temperature and moisture conditions. They were handled frequently and moved from place to place using a wide variety of transporting media. 25.1.2 Effect of distance, time, shock, vibration, air pressure, temperature and moisture to the products Transportation can be a long and time consuming process involving several handling steps, as the banana case illustrates. Transportation of goods exposures them to shock, vibration, air pressure, and moisture variations in addition to time and temperature. There are several studies on the vulnerability of foods, and how different packaging can improve or destroy the quality of a specific product (such as Chonhenchob et al. on mangoes, 2002). 3 Distribution packaging is generally tested by integrity and general simulation tests before shipment. The first step in the focused simulation test is to quantify, by actual field measurement, the distribution hazards on the packaged products in terms of their intensities and other conditions. For example, drops and impacts are measured, and the data is analysed according to the height or velocity, package orientation at impact, and frequency of occurrence. Vehicle vibrations are measured, with the data typically analysed as power spectral density plots according to the vehicle type and lading conditions, and time durations (or with a given relationship of time to trip length). Compression is measured in vehicles and warehouses, and data analysed to time and superimposed conditions. Atmos- pheric profiles are measured, and data analysed in terms of extremes, rates of change, and combinations. The measurements have become possible with the help of the currently available small, self-contained electronic field data recorders. (Kipp, 2002). 4 These instruments can record both static and dynamic information in order to get the required analyses. They are often smaller in size than a brick. Integrating intelligent packaging, storage and distribution 537 Unique systems must be designed, if temperature and humidity sensitive products are ordered by e-mail and shipped to other places (Singh, 2000). 5 Since fresh produce continues to respire after being harvested, this causes an intake of oxygen and release of carbon dioxide. The respiration rate of fruits, vegetables and flowers is dependent on temperature. An increase of package storage temperature results in an exponential increase in respiration rate that shortens the shelf-life of the produce, resulting in eventual decay. The United States Department of Agriculture has documented this information on recommended storage temperature, relative humidity and approximate shelf-life for various fresh produce (Welby et al., 1997). 6 Most fresh produce has a high moisture content, so it is important to maintain a high humidity environment during transportation in order to prevent moisture loss that would result in drying of the produce. USDA recommends a high humidity environment (80–95% relative humidity) for most fresh produce. Possible solutions include cooling aids and specially insulated packaging materials (Singh, 2002a). 7 A company in the USA selling expensive meat parts by e-mail has found an interesting method for chilling their goods. Instead of shipping meat pieces with cooling aids and fillers, frozen hamburgers are packed into the boxes serving as coolers and fillers. The customer gets a usable give-away and the extras increase the incentive for a further purchase (Singh, 2002b). 8 25.2 The role of packaging in the supply chain The main duties of packaging are to protect, contain, inform, and sell. The right packaging also preserves, as the products are received in a good and usable condition. The package needed for protection is a combination of product characteristics and logistical hazards. Well chosen packaging can reduce the cost of every logistical activity: transport, storage, handling, inventory control, and customer service. It can reduce the cost of damage, safety, and disposal. Integrated management of packaging and logistics is required, if a firm is to realise such opportunities to reduce costs (Twede, 1997). 9 25.2.1 Interviewing the food industry and trade Tekes, the National Agency of Finland, finances the ‘Safety and Information in Packaging’ program in Finland. There have been studies on the needs and wishes of industry and trade in order to gather information for directing the research program. During the summer of 2001 Pakkausteknologia – PTR (Association of Packaging Technology and Research) asked for the opinions of the Finnish food industry with a questionnaire of 93 questions (Pikkarainen et al., 2002). 10 Answers were received from producers of dry foods (sugar, flour), beverages, and ready-to eat foods, dairy products, and so on, covering the different sectors of food industry. Shocks, compression, changes in temperature and packaging closing methods all cause packaging problems for the food industry (Fig. 25.1). 538 Novel food packaging techniques The interviewees wished to gather more information on the following aspects: circumstances during the storage and transport, temperature changes, breakage of cold chain, and leak detection. They preferred additional properties to be within the packaging material, and also that the new properties would be in transport packages instead of consumer packages. They particularly wanted an active tag or a smart card containing memory to be developed for the distribution package rather than for the consumer package. The main reason is probably the price of the tags. If it were only a few cents then the tags would be accepted also for consumer packages. The profit margin in the food sector is low and therefore all additional costs must be carefully considered. Different information is required in consumer packages than in transport and distribution packages. The information in a consumer package is aimed at the consumers; retailers and other parties in the trade need information on distribution and storage conditions. All who replied wished to know about the cold chain, especially if it had been interrupted. Monitoring the temperature during distribution was an important aspect (Fig. 25.2). Only those whose products were not sensitive to temperature did not consider it very important. The majority (70%) also preferred the indicator to record information during distribution. In the ‘Safety and Information in Packaging’ program the storekeepers in Finland were also interviewed by Pakkausteknologia – PTR (Association of Packaging Technology and Research). All who were interviewed, mentioned that the most important aspects were the retail packages (the size should be right for the size of the store), environmental aspects, economics, alarm systems, and Fig. 25.1 Possible causes of trouble in packaging in food industry. Presented as an average of all answers. No problems at all is indicated by number 1, and 7 is given if major problems (Pikkarainen et al., 2002). Integrating intelligent packaging, storage and distribution 539 consumer packages. The consumer packages should be appealing to the consumer and contain information that the customer needs (Leppa¨nen-Turkula, 2002). 11 Ergonomics and ease of opening the packages at the retail level are important aspects of packaging design and are valued by the retailers. 25.3 Creating integrated packaging, storage and distribution: alarm systems and TTIs The current logistic systems use EAN-codes, shipment labels and codes, alarm systems, separate in-house control systems, and manual check-ups. Sometimes Fig. 25.2 Properties that increase information or safety on consumer or distribution packages. Presented as an average of all answers (Pikkarainen et al., 2002). 540 Novel food packaging techniques the distribution conditions are also checked with shock and vibration devices or continuous expensive devices, which monitor the time and temperature and moisture conditions during distribution. There is a need to develop an economic integrated system that would serve the different aspects of the whole chain. A producer wants traceability and an easy way to recall a product from the market. Low inventories and feed-back systems are also desirable. There is also a desire to check every actual shipment for environmental effects, and for shocks and vibrations. The main reason is to get information about where and when possible mishandlings occur so that responsibilities, liabilities, and improvements can be determined. Presently the price of the recorders and the difficulty of returning used recorders exert a pressure to develop cheaper systems that could even be added to each shipment. However, the achieved savings must be bigger than the costs. 25.3.1 Alarm systems It is estimated that shoplifters account for a $10 billion annual loss in the American retail trade. Retailers have struggled to reduce these losses by various means. Early electronic devices were cumbersome, and their cost meant that they had to be removed at the checkout counter and used again. A modern EAS (electronic article surveillance) device is paper-thin and the size of a postage stamp. The EAS is attached to the package or product. As more and more retailers are asking their suppliers to include EAS tags on their products, the problem of tagging merchandise is shifting from the retailer to the package supplier. The two systems, which are currently much in use, are acoustomagnetic and radio frequency technology. EAS will set off an alarm when the active device is passed though an EAS detection system. Acoustomagnetic uses 58 kilohertz. Demagnetising the strip or altering its magnetic properties so that it resonates at different frequency inactivates the alarm (Soroka, 1999). 12 25.3.2 In-house control At the moment all different stages of the food chain do their own in-house control tests. The storage facilities usually have temperature recorders, but how well the right temperature is maintained near doors and walkways is open to question. Is the capacity enough to cool a warmed product fast enough? The most common tests are plain visual checks, but the lorries usually have temperature recorders if they transport frozen or chilled foods. The store checks product temperatures at arrival. These sporadic tests, however, do not give continuous information. By using TTI indicators the time and temperature combined effects could be better monitored. When used in distribution packages the cost of the indicator is divided between several consumer packages. Integrating intelligent packaging, storage and distribution 541 25.4 Traceability: radio frequency identification 25.4.1 Automatic identification Automatic identification is a generic term describing various methods of data collection and entry. Automatic data collection reduces human error and speeds up the work. There are varying types of Auto ID operating in the world, many encountered on a daily basis without the users truly being aware of them. Examples of these are: card technologies, scanning devices, machine vision, optical character recognition, speech/voice recognition, radio frequency identification. Associated with an increase in entry accuracy is an overall reduction of costs as well as time savings. There are additional benefits that can be derived as well including, where appropriate, increased product or service quality, increased productivity and a reduction in inventory. 25.4.2 Radio Frequency Identification (RFID) RFID is a non-contact, wireless, data communication form where tags of some material, usually embedded with an IC chip, are programmed with unique information and attached to objects for identification and tracking. The information can be location, product name or code, expiration/product date, etc., depending on what is required. As tagged items pass by readers, the data from the tags is decoded and transferred to a host computer for processing. RFID offers practical benefits over other automatic data capture systems: a line-of- sight is not needed, it has the ability to read multiple tags simultaneously even on the move, and it is possible to write information to the tag, and so on (Clarke, 2002). 13 The main difference with EAS is that EAS gives only an alarm, but a RFID tag also identifies the article as a unique product. This increases the possibility of using the technique for recall and tracing. There are several recent articles on RFID. Articles portray a world where the items give detailed information and can communicate with each other without human intervention (Chips, 2002, Covell, 2002). 14, 15 There are also several names used: RFID tag, smart card, smart label. One of the questions is when should the RFID tag replace EAN-code in fast-moving consumer goods (FMCG)? Will it be in the next ten years or will there be only a limited use of RDIF tags? The present guess is that RFID will come first to returnable systems, such as pallets, crates and so on and later to distribution packages and to more expensive consumer goods. The main incentive to pursuing the system will be that some big retail chain such as Wal-Mart, or a producer, demands it in order to get real-time visibility in their supply chains. Actually Wal-Mart and Procter & Gamble are carrying out preliminary tests with transponders on pallets. Wal-Mart has fitted out two distribution centres as well as one Sam’s Club and one Wal-Mart store with the technology in the supply chain. The software provider is SAP (LebensmittelZeitung.com, 2002). 16 Actually, simple RFID tags are already are in use, library systems, bus and ski tickets, garment tracking, product handshaking (embedded systems). In warehouses and distribution centres some applications are in development. To 542 Novel food packaging techniques read a pallet load manually with bar codes can take up to 30 minutes, but smart labels can be read up to 1000 + tags per second automatically. The ultimate goal is real-time ‘people-free’ visibility throughout the supply chain. Trends and factors that affect the success of RFID tags, are the need for end-to-end visibility, the kind of investment that will be necessary, how open the infrastructure will be and the price level of systems. RFID technology may need some explanation. It generally uses passive tags that contain a chip and an antenna. When a host system sends power to the tag, it responds to the reader giving the information inside the chip. The tag is passive so that it needs no battery with it. There are also active tags, which have a battery. Active tags can be used to record information during the shipment or can be used to give information from a longer distance. Even the passive tags (transponders) and integrated host systems and readers make wireless data carrier technology available to manufacturer, supplier, retailer, and consumer. Transponders can be added to labels, packages, and products. RFID and standardisation There are several RFID frequencies in use: 125–134KHz, 13.56MHz, UHF 862– 928MHz, 2.45GHz, and 5.8GHz. In order to get a system that can work globally, there is a need for RFID standards. The following standards are available: ? ISO/IEC 15693-1:2000 Identification cards – Contactless integrated circuit(s) cards – Vicinity cards – Part 1: Physical characteristics ? ISO/IEC 15693-2:2000 Identification cards – Contactless integrated circuit(s) cards – Vicinity cards – Part 2: Air interface and initialisation (available in English only) ? ISO/IEC 15693-2:2000/Cor 1:2001 (available in English only) ? ISO/IEC 15693-3:2001 Identification cards – Contactless integrated circuit(s) cards – Vicinity cards – Part 3: Anticollision and transmission protocol (available in English only) AIM (Association for Automatic Identification and Data Capture Technologies) has listed in its web pages all different standards that may affect the usage of RFID (www.aimglobal.org, 2001): 17 JTC 1/SC 31 Automatic identification and data capture techniques JTC 1/SC 17 Identification cards and related devices ISO TC 104 / SC 4 Identification and communication ISO TC 23 / SC 19 Agricultural electronics CEN/TC 278 Road transport and traffic telematics CEN/TC 23/SC 3/WG 3 Transportable gas cylinders – operational requirements – identification of cylinders and contents ISO/TC204 Transport information and control systems ETSI European Telecommunications Standards Institute ERO European Radiocommunications Office Integrating intelligent packaging, storage and distribution 543 ANSI American National Standards Institute Universal Postal Union ASTM RFID now There was a major decision made in June 2002. EAN UCC (EAN International and Uniform Code Council) has taken some steps to launch GTAG (EAN 2002). 18 The technical foundation for GTAG-compliant products is aligned with standards being developed under the auspices of the international Organization for Standardization (ISO), and specifically the work of JTC1/SC31/WG4, and SG3. One of the deliverables from this Working Group and Sub-Group is a standard for the air interface (RF communications link) between reader and tags, which, through technical due diligence, has been chosen by the GTAG Project Team as the interface for GTAG-compliant systems. This specification is ISO 18000-6. The present state of this specification is a Committee Draft (CD). Auto-ID Center is a strong global promoter of wireless identification technologies. It is founded to develop network solutions and software for RFID technology and create an infrastructure throughout the entire retail supply chain. Its message is to get the next wave of the Internet revolution going; ‘all sorts of objects communicating with each other without people being involved’ (www.autoidcenter.com). Finnish Rafsec supplies the intelligent tags, which support the Auto-ID Center′s specifications for the low-cost tags (mass production from roll to roll). They cost now about 50 cents each. Rafsec produces the RFID transponders, the antenna and the fixing of the chip to the tag and antenna. The RFID chip generally contains memory from 512 bits to 2kb. The transponders are thin and flexible in form, they have read and write capabilities, and each chip is unique! So every product is unique after it is tagged! The information is coded in, the transponder is robust and it survives the whole life cycle and operates at temperatures from 25oC to +70oC. It can for a short time stand even a temperature of 150oC, which means that it can survive in a car tyre or in an injection moulding. When using 13.56MHz, the tag can be read from up to a one metre range at a relatively high data rate. A number of pilot projects are under way, but the threshold to use the systems is high (Savolainen, 2002a and b). 19, 20 The possibility of reading simultaneously through material at a distance provides interesting features. One can get exact information of a pallet load even though some products are removed. Of course there are also weaknesses in RFID technology; metal affects the signal so it will not read products in a metal cage. Also liquid materials can affect readability (Cole, 2002). 21 EAN UCC has been active with RFID. The use of a RFID tag in the supply chain offers a solution to multiple labelling during logistics. When a product is produced the only known information is the product identification, the batch number, and the production date. The logistic, transport and customer information will be known later on. The unique RFID tag would not replace 544 Novel food packaging techniques the entire printed label, but it will be the unique support on a logistic unit for capturing or writing computerised data. The new support could provide significant improvement in the supply chain, such as ? reduction in the number of labels printed by each party ? reduction in the number of barcode printers and label applicators in plants, warehouses and plate-form ? simplification of the reading and writing process. The EAN UCC report specially mention the possibility of tagging the support pallet. This makes the tag reusable, simplifies the replenishment of tags and allows the costs to be divided by the number of times it is reused. It also provides the opportunity to use this tag for the tracking of the pallet support itself. According to the general EAN UCC specifications, the only mandatory data that is required on a logistics unit is the serial shipping container code (SSCC). Additional common information is the batch number, best before date, net weight, the consignment number and ship to or deliver to postal code. In addition, one of the advantages of the RFID tag is that it enables the repetition of a particular piece of information, so that on a mixed pallet all required information of all components can be found (EAN UCC, 2002). EU and RFID research The EU has financed ten projects relating to RFID technology (www.cordis.lu, 2002): 22 1.Laundry application using RFID tags for enhanced logistics. 2.Trial of intelligent tag on industrial environment. 3.Passive long distance multiple access high radio frequency identification system. 4.Grocery store commerce electronic resource. 5.ParcelCall – an open architecture for intelligent tracing solutions in transport and logistics. 6.Development of an integration method of low-cost RFID tags in injection moulded and blow moulded packaging systems. 7.Inductively powered universal telemetry systems. 8.Intuitive physical interfaces to the www. 9.Hardtag – development of an industrial RF tagging technology to enable automated manufacture of ‘one-off’ and small batch products. 10. Radio frequency identification system I.CODE. 25.5 Future trends 25.5.1 The next wave of the Internet The next wave of the Internet revolution provides that all sorts of objects communicate with each other without people being involved. The products Integrating intelligent packaging, storage and distribution 545 come to the warehouse along a line, all codes of pallet loads are read to the computer and the automatic transport vehicles shift the products to the right shelves, from where they are then shipped further, on customer demand, without anyone touching them. With RFID, Bluetooth and Internet technologies it is already possible to detect when an expensive delivery is coming to a building site. Systems, of course, shall be first applied to more expensive products and to products that must be delivered to a site at an exact time. As computers have changed in 30 years, so these technologies will become cheaper and more common in the near future. The RFID technology is already in use in some ‘handshaking’ cases, the main usage areas now being in assembly lines. There are also some printers, which accept only the right colour carriage, as there is a microchip and antenna in the carriage and a reader in the printer to detect this. There are several businesses and industries that can benefit from the use of RFID tags; package delivery, consumer product manufacturers third-party logistics, retail, airlines, legal, medical, insurance, electronics, automotive, government. There are several places where tags can be read; in yards, on trucks, at sea, rooms, zones, dock doors, shelves, doors, conveyors, en route. The list of tagged assets is even longer; items, boxes, totes, pallets, trays, tubs, sacks, cartons, books, documents, files, handling equipment, containers, rail cars, trucks, forklifts, trailers, capital equipment (d’Hont, 2001). 23 How can the food industry use tags and their capabilities effectively for its own special needs? It must actively take part in research in this field or the systems and standards will be developed by others. The present development of RFID tags solves the problems of traceability, and information banks can be of great help. Maybe in the future the consumers also will get the required information easily, entertainingly and accurately. What intelligent and active features can be added to the new technology? Can techniques such as TTI or product freshness indicators be added to this technology? Can the RFID tag tell that a product is getting close to its best before date? Can it record the time and temperature? Can it be used also in-house control systems? 25.5.2 Traceability There are more and more demands for traceablity. The BSC and other incidents, such as food poisonings, have been the main cause of plans to increase traceability. We should be able to trace and recall if necessary not only the product but also all its ingredients and packaging materials. The idea is that product recall could be made precisely within an in-house control system in the whole food chain. There would be a pallet with a barcode lot number. The pallet contains products whose batch identity is known, and all of the ingredients, premixes and packaging materials can be traced by their own ID numbers. Of course we would then also know where each pallet is delivered and where the products are put on sale. 546 Novel food packaging techniques 25.5.3 Information banks EAN is collecting large information banks, from where typical information on fast moving consumer goods (FMCG) can be retrieved for the wholesalers, retailers and in the future maybe also for the customers. Currently the EAN- number provides information on the product and its package. If the RFID tags in the future become common as EAN-code is today, all parties will get more information on the product and its properties in an easy way. The communicating information banks would be at our doorsteps. 25.5.4 Consumer behaviour A number of very different segments of consumers already exist. Here are only a few examples served by the food sector: Not willing to spend time in mega stores Some of us are not keen on everyday shopping. Shall we go to the shops or order only via Internet and expect the products to be delivered to our home? There are already automats available that heat up the chosen frozen food according to the instructions on the package and tell the customer when the food is ready. Automats are replacing daily meal-to-home delivery systems with fortnightly refills. My diet is this, find suitable new products There are more and more people who must follow a certain diet. If your mobile phone communicates with the RFID tags on the products in the store, it could in future tell you that this or that product is good for your diet. ‘You need more vegetables in your diet, try those. Get the new instructions at the store computer.’ I am bored, give me pleasure, enjoyment . . . Enjoyment, excitement and other psychological aspects are becoming more and more important. Active systems in packages may give the consumer a new interest in buying a certain product. 25.6 Sources of further information and advice In addition to general packaging books and magazines, the following Internet pages are worth visiting as certain aspects such as the RFID are in rapid developmental stages. www.aimglobal.org www.autoidcenter.com www.cordis.lu www.ean-ucc.org www.pakkausteknologia-ptr.fi www.rafsec.com Integrating intelligent packaging, storage and distribution 547 25.7 References 1. ISTA, The Association for Transport Packaging (2002), ‘INSTA and package performance testing: how they contribute to the quality of life’ Worldpak 2002, Improving the quality of life through packaging innovation, Proceedings of the 13th IAPRI conference on packaging, June 23–28, 2002 East Lansing, Michigan, USA, CRC press, ISBN 1- 158716-154-0 p. 179. 2. LEPPA ¨ AHO K (2002) Personal information in Finnish, Kesko 30.10.2002. 3. CHONHENCHOP V and SILAYOI P (2002) ‘Comparison of Various Packages for Mango Distribution in Thailand’, Worldpak 2002, Improving the quality of life through packaging innovation, Proceedings of the 13th IAPRI conference on packaging, June 23–28, 2002 East Lansing, Michigan, USA, CRC press, ISBN 1-158716-154-0 pp. 3–11. 4. KIPP W (2002) ‘The technology of transport packaging evaluation’, Worldpak 2002, Improving the quality of life through packaging innovation, Proceedings of the 13th IAPRI conference on packaging, June 23-28, 2002 East Lansing, Michigan, USA, CRC press, ISBN1- 158716-154-0 pp. 180–9. 5. SINGH S P (2000) ‘Packaging Requirements for Shipping Fresh Produce Using E-commerce’, Marcondes J, Advance in Packaging Development and Research, Proceedings from the 20th International Association of Packaging Research Institutes Symposium, San Jose State University pp. 500—6. 6. WELBY E and MCGREGOS B (1997) Agricultural Export Transportation Handbook, USDA. 7. SINGH S P and SINGH J (2002a) ‘E-commerce distribution of fresh produce and flowers’, Worldpak 2002, Improving the quality of life through packaging innovation, Proceedings of the 13th IAPRI conference on packaging, June 23–28, 2002 East Lansing, Michigan, USA, CRC press, ISBN1-158716-154-0 pp. 446–54. 8. SINGH, S P (2002b) Personal communication during the presentation 24.6.2002. 9. TWEDE D (1997) ‘Logistical/distribution packaging’ in Brody A and Marsh K, The Wiley Encyclopedia of Packaging Technology, second edition, John Wiley & Sons, Inc ISBN 0-471-06397-5 pp. 572–9. 10. PIKKARAINEN K and JA ¨ RVI-KA ¨ A ¨ RIA ¨ INEN T (2002) ‘SIP -pakkaustutkimus ka¨yntiin tarvekartoituksella’, Kehittyva¨ elintarvike 2/2002 pp. 38–9. 11. LEPPA ¨ NEN-TURKULA A (2002) ‘Mita¨ kuluttajat odottavat pakkauksilta pa¨ivitta¨istavarakaupoissa, kauppiaiden na¨kemyksia¨’, Oral presentation at SIP vuosisemiaari Vantaa, Finland on 8.10.2002. 12. SOROKA W (1999) Fundamentals of Packaging Technology, Institute of Packaging Professionals, ISBN 1-939268-06-8, pp. 499. 13. CLARKE R H (2002) ‘Radio Frequency identification: will it work in your supply chain?’ Worldpak 2002, Improving the quality of life through 548 Novel food packaging techniques packaging innovation, Proceedings of the 13th IAPRI conference on packaging, June 23–28, 2002 East Lansing, Michigan, USA, CRC press, ISBN1-158716-154-0 pp. 655–62. 14. ‘Chips with everything’ (2002) New Scientist, 19.10.2002 pp. 44–7. 15. COVELL P (2002) ‘Smart money on RFID’, Packaging Today International October 2002, pp. 28–31. 16. LebensmittelZeitnung.com June 13.2002 (http://english.lz-net.de/news/ webtechnews/pages/showmsg.prl?id=1217) (available via Internet on 1.11.2002). 17. http://www.aimglobal.org/standards/rfidstds/RFIDStandard.htm 2001 (available via Internet on 8.11.2002). 18. EAN UCC (2002) White Paper on Radio Frequency Identification, June 2002, EAN International and Uniform Code Council, Inc. http/www.ean- ucc.org/gtag.htm 19. SAVOLAINEN S (2002a), RFID:lla¨ a¨lyka¨s ja turvallinen pakkauskonsepti, A ¨ lykka¨a¨t ja aktiiviset materiaalit pakkauksissa 21–22.5.2002 Suomen Kemian Seura. 20. SAVOLAINEN S (2002b), Personal communications on 5.11.2002. 21. COLE P H (2002) White paper: A study of factors affecting the design of EPC antennas & readers for supermarket shelves. Auto-id centre. June 1, 2002. 22. www.cordis.lu. search about RFID on 5.11.2002. 23. D’HONT, SUSY, Smart labels – hype or hope? The RFID Summit, Nov 12, 2001 available on the web at www.matrics.com. Integrating intelligent packaging, storage and distribution 549 26.1 Introduction: new packaging techniques and the consumer New packaging techniques promise consumers safe food products that keep their high quality throughout shelf-life. The improved quality has been achieved by applying tailored technological solutions that require highly specialised knowl- edge. From consumers’ point of view these new techniques require explanations if food can keep fresh for an unexpected and thereby unnaturally long time. Consumers in general tend to be suspicious towards novelty in food products as any new element can be potentially harmful (Rozin and Royzman, 2001). Furthermore, applying technology to achieve benefits can add to distrust as technology by itself can have negative connotations. Understanding how the benefits have been achieved requires advanced consumer education on the principles of food spoilage. The basic functions of the package have been described as containing the foodstuff, protecting and maintaining its quality, providing information for the consumer, convenience in use, being environmentally friendly, and selling the product (Hurme et al., 2002). For consumers, the favourable packaging attributes include convenience in opening, resealing, storing and disposing (Eastlack et al., 1993; Mikkola et al., 1997). These positive attributes are almost all related to the practical properties of packages and how easy they are to use, but include no safety issues. Similarly, most negative attributes referred to lack of convenience, the only safety related attributes listed were ‘product spoils easily’ and ‘can spill or leak’ (Eastlack et al., 1993). Most active and intelligent packaging methods aim at improving the quality and safety of food products. The improvement of safety by producing longer 26 Testing consumer responses to new packaging concepts L. La¨hteenma¨ki and A. Arvola, VTT Biotechnology, Finland safe shelf-life may be a hard concept to sell to consumers. Safety is likely to be for consumers a self-evident feature and therefore regarded as a basic requirement in packed food products. Therefore, consumers do not assess the package based on its safety merits, rather they assess the convenience of using the pack when taking the presumably safe foodstuff from the package. This implies that consumers need to be educated about the possible benefits that active and intelligent packaging can provide them and treating the different types of packaging solutions as integral parts of the product rather than the foodstuff and packaging as separate issues. Although active and intelligent packaging methods have been studied widely and innovations have been developed very few of them have been developed into commercially available products (Hurme et al., 2002). One reason for the slow progress may have been the anticipated consumer concerns of these new applications. Surprisingly, however, very few consumer studies have been published on this topic. This chapter describes how different approaches can be used to study consumers’ attitudes towards active and intelligent packaging technology. The first section calls attention to the special problems that are encountered when novel technologies are studied. Then the principles of most frequently used qualitative and quantitative methods are introduced and their strengths and weaknesses are discussed. A short overview of our current knowledge on consumer attitudes towards active and intelligent packaging will follow the methodological section. The few studies carried out have mostly dealt with consumers’ attitudes towards oxygen absorbers and time-temperature indicators. The last section in this chapter will discuss the future prospects of active and intelligent packaging from a consumer standpoint; what the issues are that need to be taken into account and how to approach possible consumer concerns. 26.2 Special problems in testing responses to new packaging The novelty aspect and the fact that food products are regarded as entities including both package and foodstuff create challenges for studying consumer responses to new packaging technologies. When asked about familiar issues consumers tend to have either positive or negative attitudes that are activated by asking questions related to them. This process depends on the importance and topicality of the subject. Information on important or on relevant matters are given more attention and the belief structures tend to be more complex for relevant than for non-relevant issues. Recent exposure to the topic, on the other hand, makes the beliefs more accessible. When required to give answers about new food products or technologies these responses can be very arbitrary. People give responses although they are not sure what the question actually involves since this is the socially most appropriate and easiest way of handling questions. The issues that come out are highly dependent on the associations these new technologies create in consumers’ minds and what other matters are relevant for the consumer at the time. Testing consumer responses to new packaging concepts 551 In order to gain meaningful responses, consumers need to be made more familiar with intelligent packaging. This can be done by explaining what a concept, whether active packaging or special indicator, means or by showing concrete examples of these active or intelligent package solutions. A simple way to explain to interviewees what the applications are and how they function is a set of photographs that are easy to take to different places. Furthermore, they are the same for all interviewees regardless of the time and location. If real food packages or indicators are used, they have to be replaced at each demonstration. This will raise the expenses of the study, not to mention the amount of products that need to be carried to different locations and stored at accurate temperatures. Modern technology makes it possible to carry out research by using the internet or computer-aided data collection systems. With these applications it is possible to demonstrate how the indicators work with no need to use actual food packages as samples. The most feasible way of demonstrating these package solutions is to show food products with and without the indicators, absorbers or emitters. The responses are then related both to the example food and the packaging technology. This raises the question whether packaging technologies can be studied separately from their applications in consumer studies, as they provide improvements for the quality of food, not improvements for packaging. For consumer acceptance the perceived benefits are important. Consumers will assess the benefits they gain, but they also have concerns about how these benefits have been achieved. Furthermore, any technology that solely provides advantages for the other actors in the food chain are not easily accepted by consumers especially if they raise prices. 26.3 Methods for testing consumer responses The central objective in consumer research is to find out whether consumers are willing to accept new packaging technologies, whether there are concerns that may obstruct or delay acceptance and how the benefits provided by the new technologies are perceived. The methods used can be broadly divided into two categories; qualitative and quantitative approaches. With qualitative methods we can get systematic information about how consumers think and formulate their opinions about food and packaging related issues. These techniques are valuable when we want to gather information about the different possible concerns consumers attach to novel technologies or we want to define what the reasoning is behind these concerns. The advantage of qualitative techniques is that consumers can use their own language and expressions to describe their opinions. Often qualitative techniques are used as pilot studies for quantitative approaches, but they are gaining value as independent tools. The most frequently used qualitative methods are focus group discussion and individual interviews. Both these types of methods can be applied with different techniques depending on the question on the hand. 552 Novel food packaging techniques Qualitative methods describe how consumers think about certain issues but they do not give the frequency of these ideas or how important the ideas are to different people. Quantitative methods are used when we want to find out how many people have a certain opinion or estimate the strength of an opinion. The quantitative surveys finding out people’s opinions can be carried out as interviews or questionnaires or a combination of these. Experimental designs are a special type of quantitative study in which respondents are given different treatments, e.g., samples to try, and their responses are measured and compared in different experimental groups or with a control group. Below are short descriptions of typical features of most typically used methods and implications of their use in studying novel packaging materials. Detailed descriptions of the methods can be found in textbooks. 26.3.1 Focus group discussions Focus group discussions provide information on how consumers talk about particular issues (Casey and Krueger, 1994). Moderating focus groups require careful preparation and the questions need to be outlined beforehand. The moderator needs to be well-trained for the task and possess appropriate social skills on diplomacy and bringing all participants into discussion as equal members of the group. The basic principle is that the moderator does not lead the discussion in any specific direction, as long as the conversation remains topical. The participants in the discussion group respond with comments and opinions from each other and thus the discussion deals with aspects coming from several individuals. This social interaction enables the pondering of the importance of matters that have been raised during the discussion. Analysing the focus group data is a relatively difficult task because the material produced during interactive discussions tends to be vast and branch in various directions. Due to this heterogeneity of material Casey and Krueger (1994) recommend that at least three groups with the same questions and similar participants should be run to cover the variation. Where packaging issues are concerned focus group discussion works well with consumers because new technologies can be demonstrated as part of the group session and there is no pressure to be an expert on the topic. Experts working for retailers, food industry, authority or consumer associations may find group discussion less relaxing than consumers, since these individuals should be knowledgeable about the novel packaging developments. This may cause tension in a group discussion. If the aim in discussion is a free exchange of ideas and views about the future, tension may exclude some participants from the discussion or ideas and opinions are carefully controlled. Therefore respondents with vested interests in the topic are easier to handle in a one-to-one interview situation. 26.3.2 Qualitative and quantitative interviews Interviews allow direct interaction between respondent and interviewer. Individual interviews can be carried out using several techniques. Some Testing consumer responses to new packaging concepts 553 techniques follow very structured procedures with a predefined order and form of questions; others allow an interviewee’s responses to delineate how to continue as long as the relevant topics are discussed. The type of interview is typically selected on the basis of research questions. Packaging issues are rarely sensitive issues and are therefore easy to talk about. Often in this type of study either semi-structured or structured interviews have been used. Qualitative interviews are used when we want know how respondents think about packaging and we do not have enough previous knowledge about what the possible responses can be. The approach is suitable for examining more complex issues as participants are not restricted in predefined response alternatives. Data analysis with a qualitative approach tends to be time consuming and the researcher has to be very skilful in analysing transcripts of focus group discussions. If we want to quantify responses the interviews are typically carried out with structured outlines and sometime the possible response alternatives are preselected. The advantage of carrying out an interview survey rather than a questionnaire is that interviewees can ask for explanations if they do not understand questions and also interviewers can ask for elaboration if the responses contain ambiguous expressions. With novel packaging solutions, using interviews enables a demonstration of what these absorbers and indicators are like when they are attached to the food package. 26.3.3 Questionnaires Questionnaires offer a relatively inexpensive method to study what people think about an issue on average. A questionnaire approach can be selected if we know well enough what the possible response alternatives are that consumers are likely to give or we have an explicit predefined question. With appropriate sampling techniques the respondents can be selected to fulfil certain predefined criteria. Typically respondents are selected based on their socio-demographic background (sex, age, education, profession) or based on their consumption or buying habits. Often food-related studies are targeted on those who typically use the product or questions are asked of those who have the main responsibility for food choice in their own household. Due to the latter criterion, the majority of the food or packaging related studies have had mostly female respondents (Anon., 1991; Korhonen et al., 1999; Mikkola et al., 1997). The limitation of questionnaires in packaging related research is that items in a questionnaire should refer to familiar things. If consumers are asked opinions about themes they are not familiar with, the reliability and validity of these responses may not be very good. There are several textbooks describing how to construct a questionnaire and ask factual and attitudinal questions, but the basic rule is that the questions should be easily comprehensible and provide alternatives that consumers can relate to. 554 Novel food packaging techniques 26.3.4 Experimental designs Experimental designs are useful when novel applications in the food domain are studied as they provide a chance to familiarise the respondents with the new technologies and thus reduce fears that rise from uncertainty. The designs also enable controlled comparisons of consumer responses to different types of packaging solutions. Consumers can experience concretely how indicators or absorbers look and function and what their advantages are. In most experimental set-ups there is a need for a control product, which is often the same product packed without the indicator or other active component. This enables a direct comparison of how acceptable the new applications are in relation to the existing packaging methods. As most consumer responses tend to be relative, the experimental design can produce more reliable information in this sense, although the drawback is that instructions tend to make the assessments rather artificial. 26.4 Consumer attitudes towards active and intelligent packaging 26.4.1 General attitudes The idea of active and intelligent packaging has received a generally positive response from consumers and their representatives. The reason may be that they seem to provide solutions to consumer concerns. According to Korhonen et al. (1999) about half of Finnish respondents (n 460) did not trust that all food products would still be edible on their expiry date. Half of the consumers also reported that they would choose packages from the bottom of a chilled counter to ensure the freshness of the product. The active and intelligent packaging methods were more familiar to those who were involved with packaging issues. A small number of individuals (n 21) who are responsible for delivering information to consumers about the packaging issues in Finland were interviewed in 1995 (Mikkola et al., 1997). The group consisted of retailers, journalists and government officials. When asked whether they were familiar with modified atmosphere and vacuum packs, four out of five interviewees could recognise both of these. Furthermore, about half of the respondents could recognise moisture absorbers (57%), oxygen absorbers (52%) and time- temperature indicators (42%). The interviewees had a positive attitude towards these examples of active and intelligent packaging, especially if applied to foods that are easily perishable, such as chilled foods, vegetables, some bakery products, meat or fish products. People have different requirements for food packaging. In a study carried out in the UK (Anon., 1991) consumers could be divided into three groups according to their attitudes towards the safety of chilled foods. The ‘ultra- cautious’ are likely to throw away all foods that have passed the use by date, the ‘cautious’ use their own judgement and believe in some safety margins around the given dates, whereas the ‘non-cautious’ care very little about dates. A Testing consumer responses to new packaging concepts 555 considerable number of consumers fell into the ‘ultra-cautious’ category whereas the ‘non-cautious’ were in a minority. The study itself targeted consumer acceptance of time-temperature indicators and reflected the acceptance of these new devices to the needs these three respondent groups had. 26.4.2 Acceptance of oxygen absorbers When asked about the possible benefits of absorbers or emitters, the interviewees (n 21) mentioned that food products retain their good quality longer, which may be especially helpful for small households and those who shop once a week (Mikkola et al., 1997). The absorbers were believed to improve safety by reducing microbial risks and thereby contributing to a decrease in the use of additives in food products. On the negative side, the added components can increase price and produce more waste. People also may eat older food if it keeps a longer time in good condition. Furthermore, the possibility that these absorbers or emitters could contain harmful substances that may be ingested by vulnerable consumer groups, such as older people and children, caused concern. Acceptance of oxygen absorbers among Finnish consumers was examined with an experimental design. Mikkola et al. (1997) carried out a study where consumers (n 346) were given two types of food products to take home. Sliced rye bread and pizza filled with ham were packed with or without oxygen absorbers. The products were stored at the research institute so that their delivery date was close to the best by date. A trained laboratory panel assessed the samples and gave higher quality points on appearance, flavour and freshness for pizza when it was packed with the absorber than when it contained no absorber, but there was no difference in the assessed quality of sliced rye bread. Consumers, however, assessed both products with oxygen absorbers as having higher quality, although the difference between oxygen absorber product and conventional product was small for rye bread. In the trained panel evaluation the samples were blind coded and the panel did not know what the samples were when they tasted them. Consumers, on the other hand received the samples clearly labelled and based their assessment on both sensory quality and on information they received. In addition to overall quality, respondents were asked to evaluate whether they were willing to accept the absorbers and buy these products if they were available on the market. The oxygen absorber used in the study was a loose sachet enclosed in the package and half of the respondents also received an information leaflet that described what the oxygen absorber was, how it functioned and how it could be disposed of (Mikkola et al., 1997). After the demonstration with real food products 72% on average were ready to accept these additional sachets, 23% were unsure and 5% were clearly negative. From those who received the additional leaflet 76% accepted the oxygen absorber vs. 67% in the no- information group. Information decreased the number of unsure people among the respondents but had no effect on the size of the negative group. 556 Novel food packaging techniques Respondents’ attitudes towards oxygen absorbers were positive (3.8/max 5), respondents would rather favour than avoid them (3.6/max 5) and evaluated them more necessary than unnecessary (3.4/max 5) (Mikkola et al., 1997). Those who were most positive about oxygen absorbers were also positive about pre-packed food, use of additives and long shelf-life. When asked about the acceptance of oxygen absorbers in different types of meat products, use in pizza (62%), meatballs (48%), sausages (37%) were accepted best, while in fresh meat only 29% would accept them. The high acceptance rate in pizza illustrates the usefulness of the demonstration material in the study. Consumers could experience with their own senses what the benefits in pizza were and thus the acceptance rate is high. The low acceptance rate in fresh meat indicates that an idea of prolonged shelf-life is not considered as acceptable in fresh products. In bakery products the highest acceptance rate was again in the product used in the demonstration, namely rye bread (57%), but all other examples were also accepted by half of the respondents (50 55%). Furthermore, when asked about willingness to pay more if the products contained an oxygen absorber, 40% of the respondents were willing to pay 0.15C= more. 26.4.3 Acceptance of time-temperature indicators The concept of time-temperature indicators (TTIs) has been well received in consumer studies (Anon., 1991; Korhonen et al., 1999; Sherlock and Labuza, 1992). In a UK study (Anon., 1991) the majority of respondents (95%; n 511) considered TTIs as being a good idea because they show whether food is safe (28%), whether it is kept at the right temperature (21%) and whether food is fresh (16%). In an American questionnaire study (n 104) 90% considered TTI tags as a desirable addition and 97% believed that they would increase confidence in the freshness of the product (Sherlock and Labuza, 1992). The study was carried out to find out how consumers react to the use of TTIs in refrigerated dairy products. In a small interview study (n 21) carried out in Finland by Mikkola et al. (1997) a time-temperature indicator (TTI) created less uncertainty than an oxygen absorber. Increasing safety was perceived to be an obvious benefit because consumers do not have to trust merely their own senses. The suspicion that these indicators may give inaccurate information and thereby cause a safety hazard was mentioned as a drawback together with adding price and waste (Anon., 1991; Mikkola et al., 1997). In three focus groups (Sherlock and Labuza, 1992) run in Nebraska, the TTI tags were considered to be clever devices that could be used to differentiate products on the market, but they were not perceived to replace date markers. Furthermore, the discussion brought to light a need for a consumer campaign before these tags could be used as a marketing tool, since consumers need to be informed about their benefits. The TTIs were perceived to be most suitable for frozen food and freshly prepared refrigerated entre′es, but not dairy products (Sherlock and Labuza, 1992). In a Finnish study (Korhonen et al., 1999) TTIs were regarded as necessary to most products but the most necessary targets were packaged fresh Testing consumer responses to new packaging concepts 557 meat or fish, smoked fish, meat products, foods for children or ready prepared foods. Over 80% regarded TTIs as necessary in these applications although they were told that TTIs would increase the price of the product by 8.5 cents. This study was carried out as a survey in which participants (n 460) were asked to fill in a questionnaire. While responding to the questionnaire consumers could observe models of TTIs used in packages. Similarly, 59% of the respondents in the UK expressed their willingness to pay more for chilled products that contained a TTI tag (Anon., 1991). The result that TTIs are more suitable for fresh meat (Korhonen et al., 1999), whereas oxygen absorbers were considered acceptable in fresh meat by only by a minority of respondents (Mikkola et al., 1997) elevates the importance of perceived consumer benefit and understanding the reasons for food choices. The apparently contradictory result may be easily explained by the different functional principles of these two packaging devices, which may have a different appeal to consumers. The oxygen absorber could prolong the shelf-life of fresh meat, whereas the time temperature indicator shows only how it has been operated through the chill chain. The idea of extending the shelf-life of fresh meat is not attractive, but it is important to know if the fresh product is still in prime condition. This highlights the fact that all these different applications have to be studied as separate concepts in consumer studies. Measuring an overall attitude towards active and intelligent packaging is not feasible, as the benefits and possible concerns are specific to each application. Some worries about possible tampering with TTIs in the shop were brought forward (Anon., 1991; Korhonen et al., 1999). One worry was that the shopkeeper could possibly change the indicator and thus mislead consumers. In the UK (Anon., 1991) the non-cautious respondents perceived the TTIs to the unnecessary and some reported that they would deliberately sabotage them if they appeared on the market. The technical reliability of the indicators was also questioned; other markings should be clear so that consumers would not have to trust solely the indicator. In general, people seemed to trust the TTI indicators. When respondents had to make assessments on the quality of a food product they seemed to place more trust on the TTI tag than on the date mark (Anon., 1991; Sherlock and Labuza, 1992). A vast majority in a study carried out in the UK (Anon., 1991) said that they would not buy a product even though the product was not past the best before mark, if the indicator had changed. If the situation was the other way around and after the best before date but the indicator showed that the product was good, about half of the respondents thought it was safe to eat. Over half of the respondents would use their own judgement to decide whether the food was edible, a third would adjust the temperature in the fridge and one in five would throw the food away. In an American study (Sherlock and Labuza, 1992) 80% would not purchase a product if the date stamp indicated freshness but the TTI tag had changed. If the situation was the other way around 49% said that they would not be likely to buy the product. Although respondents seemed to trust the indicators more, having both date marks and indicators were perceived to be the 558 Novel food packaging techniques best solution in these studies. In the UK 88% thought both should be on the package and only about 11% would have been happy with either date mark or TTI (Anon., 1991). In the USA 75% thought that both should be attached to the package, but acceptance for the date mark (23%) and TTI tag (24%) were equal (Sherlock and Labuza, 1992). This may be due partly to the way the question was asked. In the UK the study respondents had to make choices between the alternatives, whereas in the American study the questions were asked on separate rating scales. Therefore the same people could support the self- sufficiency both of date stamps and TTIs. Having TTIs in the package increased respondents’ willingness to buy the product by 72% (Sherlock and Labuza, 1992). The date marks and TTIs were regarded as tools that can complement each other and thus give a better guarantee of product quality (Anon., 1991; Sherlock and Labuza, 1992). In the study carried out in the UK (Anon., 1991) the time-temperature indicators were also regarded as tools to educate consumers on how to keep food at home. If the product is in prime condition when bought and then the indicator changes rapidly at home, this may tell the consumer that the product has been stored in too warm an environment. The indicator would clearly demonstrate to consumers the need for appropriate practices in handling foods that should be kept refrigerated. 26.5 Consumers and the future of active and intelligent packaging Active and intelligent packaging technology offers several benefits to consumers. The different absorbers and indicators can be used for various purposes. The basic purpose is to guarantee that the food products are safe and keep their quality better. The performance of distinct applications of active and intelligent packaging is based on several mechanisms: some measure time and temperature sum, others absorb certain compounds that promote spoilage, and others, excrete beneficial compounds (Hurme et al., 2002). The technological possibilities are well ahead of commercial applications, which may be due to suspicion about consumer attitudes towards these new devices. Consumers tend to be sensitive about novelty in the food domain, as food ingested and incorporated in the body could be an unknown substance and a potential source of risk. As with all innovations, innovators themselves and early adapters are the first to adopt them, then acceptance spreads to the majority of the population. According to Eastlack et al. (1993) adoption happens relatively rapidly for new packaging solutions. This may be due to the high exposure consumers have to new packaging solutions during their weekly visits to supermarkets or grocery stores and the low risk of these products. Nevertheless, to gain success in the market the new packaging solutions need to provide consumers with benefits or solutions to their current problems. Testing consumer responses to new packaging concepts 559 The challenge for new packaging solutions is how they and their benefits are made familiar to the consumers. Experts and consumers in the few studies that have been carried out have emphasised the need for information (Anon., 1991; Mikkola et al., 1997; Sherlock and Labuza, 1992). The tools mentioned were both product-related information in the stores and packages and wider campaigns in the media, which is the main source of information for many (Anon., 1991). A public campaign can explain what the indicators and absorbers are, what they are used for and what their limitations are. Providing this information, such as a description of the operating principles, is a basic requirement but it may often not be sufficient to gain public acceptance. In written texts the information tends to be on an abstract level and it does not remove the unfamiliarity of the new applications effectively. Making it possible to observe what the absorbers and indicators look like, and how they work and change in different conditions, makes these devices realistic options for consumers. As the benefits tend to be on the product rather than the package, consumers need demonstrations with those products that are the target applications of active and intelligent packaging. As both information and demonstration are required, the promotion of new packaging devices needs to done carefully. Although information as such is a weak motivator for choices (Mikkola et al., 1997), consumers need to know how the different indicators work, what they tell about the product and also what they do not tell. The open information policy enables consumers to make their own decisions whether to buy the products with indicators and assess how trustworthy they are in different situations. The familiarising process was described in focus group discussions carried out in the UK (Anon., 1991). Participants did not know very much about the TTIs before the principles behind the indicators were explained. The attitude towards indicators turned from scepticism to something more positive during the group discussion when different possible benefits and disadvantages were debated. The few example studies on oxygen absorbers and time-temperature indicators show that the improved freshness and safety of products are regarded as real benefits by consumers and the responses to these new packaging tools have been positive in general. Monitoring the freshness of the product is an obvious and definite advantage for consumers as it provides better tasting products for consumers. The improved safety may be a more complex benefit for consumers, as it is avoidance of a negative effect. Safety in food products is an attribute that is assumed to be in order if food is sold in the store. Everyone agrees that safety is a crucial quality factor, but when consumers are asked for the reasons behind their food choices safety is not typically mentioned (Lappalainen et al., 1998). Also, emphasising improved safety raises a question in consumers’ minds about whether the food products have not been safe before. As was expressed by consumers in the few studies carried out on active and intelligent packaging, these new techniques may be more beneficial for the food industry and retailers than consumers, but consumers still have to pay the price (Anon., 1991). The worries included the fact that the shelf-life of products will 560 Novel food packaging techniques extend and thus consumers will receive food less fresh than formerly (Mikkola et al., 1997). In addition to oxygen absorbers and TTIs, a wide range of absorbers, emitters and indicators have been developed or are under development (Hurme et al., 2002). Some of them offer benefits for all actors in the food chain, others to only some. Leak indicators are developed to detect if modified atmosphere packages leak and thus the quality and safety of the product is in jeopardy. If damaged packages can be removed from the shelf before the consumer buys them this will guarantee better quality for the consumer and improve safety. The drawbacks are additional cost and waste. The crucial question is how these indicators will affect the price and who is going to pay. If the price rises, the consumer will be the final payer but if the indicators are financed through decreased spoilage and losses the consumer benefit is clear. Ethylene absorbers can keep fruit and vegetables fresh for longer and reduce waste but some of the compounds used can be toxic if ingested. Flavour-scalping materials can modify the flavour of the product, maintain it fresh by absorbing unwanted compounds and by emitting desired compounds to the product. Some materials are used to mask bitter flavours in citrus fruit (Hurme et al., 2002). The success of these packaging solutions will depend on how consumers perceive their benefits and whether they are willing to pay extra for these. The existing studies illustrate that asking consumers their attitudes towards active and intelligent packaging in general bears little relevance to the acceptance of distinct packaging solutions, since most consumers have only a vague idea about what different terms mean. Nonetheless, when consumers are presented with different applications that belong to this category, they can accurately evaluate the possible benefits these applications can provide for them. Therefore the acceptance of active and intelligent packaging has to be studied separately for each application. The general attitude studies and focus group discussions give an idea of the factors that cause concern among consumers in packaging issues but the product related responses can reflect these worries to a varying extent and often differ from general concerns. The realistic examples of products presented to consumers may help them to evaluate their responses in relation to other motivations present in food choice situation. Clear demonstrations also provide information about how the indicators work and increase trust in them. When something is presented as an abstract idea the application may sound more technical, distant and also scary than when the real application can be observeded. Further development in intelligent and active packaging will provide completely new benefits to consumers. So far the intelligent packaging concepts have dealt with the safety and quality aspects of foods. In the future, it is likely that intelligent and smart tags can contain abundant information about the product characteristics, the amount of information being now limited by the available space on the package. Each product can be labelled to provide targeted information about the origin and composition of the product. The information may include the nutrient content and possible allergens in the products. Also the Testing consumer responses to new packaging concepts 561 environmental load of the product and packaging material can be included together with instructions on how to dispose of the package. 26.6 References ANON. (1991), Time-temperature indicators: Research into consumer attitudes and behaviour, MAFF, Food Safety Directorate, UK. CASEY MA and KRUEGER RA (1994), ‘Focus group interviewing’, in MacFie HJH and Thomson DMH , Measurement of Food Preferences, London, pp. 77– 96. EASTLACK JO, DI BENEDETTO CA and CHANDRAN R (1993), ‘Consumer Goods packaging Innovation and Its Role in the Product Adoption Process’, J Food Prod Market, 1, 117–33. HURME E, SIPILA ¨ INEN-MALM T and AHVENAINEN R (2002), ‘Active and intelligent packaging’, in Ohlsson T and Bengtsson N, Minimal processing technologies in the Food Industry, Woodhead, 87–123. KORHONEN V, JA ¨ RVI-KA ¨ A ¨ RIA ¨ INEN IT and LEPPA ¨ NEN-TURKULA A ( 1999), ‘Consumers’ attitudes towards active and intelligent packaging technologies’ Conference presentation in Challenges of the Packaging in the 21st Century, IAPRI World Conference on Packaging, Singapore. LAPPALAINEN R, KEARNEY J and GIBNEY M (1998), ‘A Pan EU survey of consumer attitudes to food, nutrition and health: an overview’, Food Qual Pref, 9, 467–478. MIKKOLA V, LA ¨ HTEENMA ¨ KI L, HURME E, HEINIO ¨ RL, JA ¨ RVI-KA ¨ A ¨ RIA ¨ INEN T and AHVENAINEN R (1997), Consumer attitudes towards oxygen absorbers in food packages, VTT Research notes 1858, VTT. ROZIN P and ROYZMAN EB (2001), ‘Negativity bias, negativity dominance, and contagion’, Personality and Social Psychology Bulletin, 5, 296–320. SHERLOCK M and LABUZA TB (1992) ‘Consumer perceptions of Consumer Type Time-Temperature Indicators for Use on Refrigerated Dairy Foods’, Dairy, Food & Env Sanit, 12, 559–65. 562 Novel food packaging techniques 27.1 Introduction Modified atmosphere (MA) techniques for horticultural products are based on the principle that manipulating or controlling the composition of the surrounding atmosphere affects the metabolism of the packaged product. By creating favourable conditions, quality decay of the product can be inhibited. The different MA techniques come with different levels of control to realise and/or maintain the composition of the atmosphere around the product. Passive MA packaging (MAP), as an extreme, relies solely on the metabolic activity of the packaged product to modify and subsequently maintain the gas composition surrounding the product. Temperature has a major effect on the rates of all processes involved in establishing the gas conditions in MAP (rates of gas exchange by the product and rates of diffusion through the packaging materials) and also on the rates of all metabolic processes that will inevitably lead to deterioration of the product and finally death. Ideally, steady state gas conditions should be obtained that, from the point of retaining quality, are optimal for the product packed. The time needed for a package to reach a steady state is extremely important as only from that moment in maximum benefit from MA being realised. Depending on conditions, the time to reach a steady state could theoretically outlast the shelf life of the packaged product. Given the ubiquitous role of temperature in MAP, success or failure of the ultimate MA package for a certain product largely depends on the level of integral temperature control from the moment of packing up to the moment of opening the package by the consumer. In logistic chains without integral temperature control, the application of MAP is often a waste of time, money and produce. In spite of the important role of temperature in MAP, most MAP research trials are performed at constant temperatures, at temperatures often close to what 27 MAP performance under dynamic temperature conditions M.L.A.T.M. Hertog, Katholieke Universiteit Leuven, Belgium is known as the optimum storage temperature for the product under study. No extensive literature data is available on monitoring MAP in terms of temperature, gas conditions and product quality throughout a logistic chain. Without such a complete set of data it is difficult, if not impossible, to know why a certain MAP design failed. This could, for instance, be due to a direct temperature effect on the product’s metabolism, or due to an indirect effect through a failure to establish the intended steady state gas conditions (too high or too low), or an unfortunate combination of other factors like leakage or issues related to product quality (maturity, microbial load, etc.). This chapter will focus on the effects of dynamic temperature conditions on the performance of MAP. First of all it will discuss how to define MAP performance; when MAP can be regarded as being successful and how this can be measured. Subsequently it will discuss what risks are involved in MAP and how these risks are affected by a lack of integral temperature control in a logistic chain. This chapter will conclude with a discussion of several simple strategies to maximise MAP performance, making the best of MAP given the limited resources available. The different aspects discussed in this chapter are illustrated using simulation results from a fully dynamic MA model 12 using realistic settings for both film and product characteristics. 27.2 MAP performance The first question to answer when discussing MAP performance is how MAP performance should be defined. The aim of MAP is to inhibit retardation of product quality, the means employed to reach this aim is the application of certain optimal MA temperature and gas conditions. To grade the performance of MAP one can test whether the aim was reached (in terms of product quality) or whether the means were employed correctly (in terms of temperature or gas conditions). If life were simple these two measures would be interchangeable, as they would be strongly correlated to each other. From a technical point of view, tracing and tracking gas conditions and temperature in the logistic chain is much easier than tracing and tracking those product properties responsible for the overall product quality. However, assessing the benefits and losses in terms of product quality gives much more insight than just the observation of MA conditions getting below or above their target levels. The question that should always be asked is how possible deviations in temperature or gas condition affect the quality and keeping quality. Product quality gives static information on the status of the product at a certain moment, for instance at the point of sale. Keeping quality provides dynamic information on how long a product can be stored, kept for sale, transported to distant markets or remain acceptable to the consumer. A wide range of equipment is available to monitor temperature throughout a logistic chain. Given that most MA packages are relatively small consumer packs and given the potentially large spatial and temporal variation in 564 Novel food packaging techniques temperature within cold stores and truckloads, there is a need to measure temperature at the level of the individual packs. Cheap versatile time temperature indicators (TTI) have been developed to give an indication of the temperature history to which individual packs have been exposed (See chapter 6). Even though these TTIs can give an indication of temperature abuse somewhere in the chain, they are not intended to reconstruct a complete temperature history and, therefore, cannot be expected perfectly to explain the resulting product quality. To give an example, a TTI will not discriminate between one week’s storage at 4oC disrupted by either 12 hours of continuous 12oC or six two-hour periods at 12oC. However, for the packed product this might make a difference, especially as the product needs time to heat up. With 12 hours of continuous 12oC the product will actually be at 12oC for part of that time. Exposed to the six two- hour periods of 12oC it depends on the time in between the warm periods how warm the product eventually will get. As a consequence, the two identical TTI readings from this example, can relate to two completely different qualities in the final product. Also the order of imposed temperatures will not make a difference to a TTI reading. However, for product quality, the order of the subsequent temperatures the product was exposed to might make a difference. For instance, pre-climacteric fruit generally responds less vigorously to temperature than the same fruit in its climacteric stage. With the effect of temperature on fruit physiology depending on the physiological stage of the fruit, two comparable temperature profiles (in terms of the total temperature sum) can have different effects in terms of product quality as this depends on the timing of the temperature relative to the physiological development of the fruit. The other important aspects of the established MA conditions are the gas conditions, which are inextricably related to temperature. As for temperature, several indicators have been developed to monitor oxygen (O 2 ) and carbon dioxide (CO 2 ) in individual packages. 16 As with TTIs, these gas indicators give only an indicative value. The potential strength of the different types of indicators arises from their combined application where information on temperature and gas conditions together can give a better indication of the realised MA conditions in individual MA packs. However, defining MAP performance by the realised MA conditions in terms of temperature and gas conditions is only an indirect measure. The ultimate unambiguous measure of the success of MAP is the final quality of the product. Some aspects of product quality can be related to volatiles produced by the product (ethylene as a measure of ripening stage, specific volatiles produced during spoilage or anaerobic conditions, etc.). This opens the door to adding product specific indicators to the range of indicators already available, resulting in the type of integrated freshness indicators as described in Chapter 7. Such freshness indicators might come close to giving a good evaluation of MAP performance incorporating several aspects of product quality into the equation. However, other aspects of product quality might never lend themselves to measurement in this way. MAP performance under dynamic temperature conditions 565 In spite of the importance of product quality as the ultimate determinant of MAP performance, this chapter will mainly focus on the effect of dynamic temperature conditions on the gas conditions developing inside MAP. Most of this is ruled by relatively simple physics. The link to product quality will be made when possible, but given the vast range of products and their different ways of responding to the applied MA conditions, 2, 11 no simple rules can be laid down on how dynamic temperature conditions will affect the quality of an MA packed product. For this, product specific knowledge is required on how product physiology responds to surrounding gas and temperature conditions in relation to the product at its own developmental stage. For now, one should be made aware that MAP performance is determined by more than just temperature and/ or the established gas conditions. 27.3 Temperature control and risks of MAP Like most techniques, MAP comes with a number of potential risks that largely depend on the level of integral temperature control in a logistic chain. 27.3.1 Low oxygen Generally, MAP is designed to create low levels of O 2 that give maximum benefit by suppressing the metabolism without getting into the range of O 2 levels that might induce fermentation. The critical O 2 level at which fermentation starts to occur is defined as the fermentation threshold. 18 The O 2 level in the package is the resultant of the influx through the package and consumption by the product. Both processes depend on temperature. O 2 consumption by the product generally increases much faster with increasing temperature (3- to 10-fold from 0–15oC 11 ) rather than the permeance of the packaging material (2- to 3-fold from 0–15oC 9 ). As a result, the steady state O 2 levels in the pack will decrease with increasing temperature. The O 2 level in a MA package designed to operate just above the fermentation threshold will, as a result of an increase in temperature, drop below this fermentation threshold; the product will start to ferment resulting in the development of off-odours and off- flavours. To make life more complicated, the fermentation threshold is not a constant but can vary with temperature. 1, 3, 18 When MA packed blueberries are exposed to a temperature increase, the drop in O 2 level is combined with an increase in fermentation threshold resulting in very little scope before anaerobic conditions are reached. Polymeric packaging materials that have the same responsiveness to temperature as the packed product can prevent induction of anaerobic conditions following increased temperature. In such cases an increase in O 2 consumption rate is counteracted by exactly the same increase in O 2 influx through the packaging material with the steady state gas conditions becoming independent of temperature. One such example was described for capsicums packed using 566 Novel food packaging techniques LDPE film. 7 One can argue whether a temperature-independent atmosphere inside the package is important in its own right. The aim of MAP is to retain quality. With constant gas conditions at increasing temperatures, respiration rate and the rate of quality decay will still increase due to the increased temperature. The O 2 levels in MA packages that make use of perforated films are even more sensitive to changes in temperature, as diffusion through the holes (i.e. diffusion through a barrier of standing air) is almost independent of temperature. An increase in temperature will induce increased O 2 consumption by the product without inducing a substantial increased influx through the packaging material, resulting in a fast drop of the steady state O 2 levels. 27.3.2 High carbon dioxide Besides reducing O 2 levels in MAP, CO 2 levels are increased to further inhibit the product’s metabolism. 2 High CO 2 levels also inhibit decay by suppressing the growth of microbes, although sometimes the CO 2 levels needed to suppress microbial growth exceed the tolerance levels of the vegetable produce packaged. 4, 6 This identifies another dilemma in controlling the gas conditions in MAP. For most polymeric packaging films the permeance for CO 2 is 2- to 10-fold higher than for O 2 , 9 under aerobic conditions O 2 depletes much faster than CO 2 will accumulate. Assuming a respiratory quotient of 1 and a steady state O 2 level of 2kPa, the maximum achievable steady state CO 2 level varies between 2 and 9kPa depending on the film material. To achieve higher steady state CO 2 levels without inducing fermentation, microperforated films should be used that have comparable permeances for O 2 and CO 2 . When using microperforated films, O 2 will deplete about as fast as CO 2 accumulates, such that the sum of O 2 and CO 2 partial pressure remains around 20kPa. A microperforated MA package designed for 2kPa O 2 can therefore generate CO 2 levels of around 18kPa. For soft fruit like strawberries, these high CO 2 levels are needed to prolong shelf- life. 8, 13 However, after prolonged storage at high CO 2 (>15 kPa) CO 2 injury becomes visible from tissue defects and fermentation off-flavours. 10, 14 When exposing MA packages to dynamic temperature conditions there is a direct risk of inducing fermentation and an added secondary risk of inducing CO 2 damage due to the accumulating fermentative CO 2 . Especially for microperforated packs where the permeance does not increase with temperature, the risk of inducing fermentation and consequently the accumulation of high CO 2 levels is much larger. Scavengers to constrain the accumulation of CO 2 (Chapter 3) might limit the secondary risk of CO 2 damage but cannot prevent the direct risk of inducing fermentation. 27.3.3 High humidity With horticultural products generally consisting of up to 90% water and with their economic value often determined by the saleable weight of the crop, moisture loss needs to be limited under all conditions. Depending on how and MAP performance under dynamic temperature conditions 567 for how long horticultural products are stored, they can easily lose up to 5% or more of their harvested weight before they reach the consumer. Generally, MAP films, either perforated or not, are relatively impermeable to water vapour and therefore quickly generate high humidity levels in the package atmosphere close to saturation. With dropping temperatures the saturating vapour pressure drops as well and the colder air cannot continue to hold as much water vapour. Due to the extremely low water vapour permeance of most films, water vapour cannot leave the package fast enough, resulting in condensation in the package. This will happen with temperature fluctuations as small as 0.5oC. In the heat of harvest activities, there is often not enough capacity properly to cool the product before packing. Packing warm product in plastic film, either for MA purposes or as liners in carton boxes, followed by cool storage, also results in extreme condensation inside the package thus wetting the product. The high humidity levels generated inside MAP prevent excessive water loss from the product retaining product quality, but the presence of free water following temperature fluctuations creates favourable conditions for microbes to flourish and break down this same product quality. 27.4 The impact of dynamic temperature conditions on MAP performance As outlined in Chapter 16, different sources of variation interact with the performance of MA packages. In this chapter we discuss the effect of temperature variation over time, and how that can affect MA conditions and final product quality. To allow for some temperature flexibility, MAP should be designed to prevent those risks outlined in the previous sections (too low O 2 , too high CO 2 , too high humidity). The closer package atmospheres are targeted to what is feasible, the more likely temperature variation can induce these risks. How closely the theoretical ideal gas conditions can be approximated depends not only on the amount of temperature variation one wants to allow for but also on the amount of variation in other relevant aspects and on how temperature interacts with these. For instance, when aimed for O 2 levels are close to the fermentation threshold, depending on the variation in gas exchange rate, there is a risk that some of the packages result in O 2 levels dropping below the fermentation threshold. 5 Depending on the variation in the fermentation threshold itself and the variation in film permeability, tightness of seal, number of layers wrapped around the product, etc., the targeted safe gas conditions might need to be far removed from the theoretical ideal gas conditions. With the number of variables encountered in MA packaging it is difficult to give full coverage of all aspects of the impact of dynamic temperature profiles on MAP, as this strongly depends on the specifications of the package of interest. Some of the important aspects are now discussed using simulations of MA packaging of shredded lettuce. 568 Novel food packaging techniques The quality of shredded lettuce is often limited by browning of the cut edges. This can be controlled by packaging in <1% O 2 and 10% CO 2 atmos- pheres. 15, 17 Shredded lettuce is a product with a relative high respiration rate and a high responsiveness to temperature as expressed by the energy of activation of respiration (see Chapter 16). As a reference we simulated MAP of pre-cooled lettuce stored at a constant 4oC and packed in a polymeric bag with an energy of activation of about one-third of the lettuce itself (Fig. 27.1b and c). Steady state gas conditions (10kPa CO 2 and 1kPa O 2 ) are reached after about two and a half days of storage with O 2 levels reaching 2 kPa after one-day storage. The realised steady state gas conditions correspond to the targeted optimum values for shredded lettuce. When one realises that minimally processed products generally have a limited shelf-life, the two and a half days needed to establish steady state conditions is relatively long. For subsequent simulations an artificial dynamic temperature profile was created (Fig. 27.1a) consisting of one day at a constant 4oC followed by a two- day period of slow fluctuating temperature around 4oC and a subsequent one-day period of fast fluctuating temperature. After this, temperature was rapidly increased to a constant 12oC. Instead of assuming the lettuce to be pre-cooled, lettuce was assumed to be at room temperature when packed. As a result of packing warm lettuce, depletion of O 2 and accumulation of CO 2 was accelerated in comparison to the reference situation (Fig. 27.1b and c), the O 2 level of 2 kPa was reached only half a day after packing. Both O 2 and CO 2 show fluctuating levels in response to the fluctuating temperature of the environment. The fluctuations in O 2 and CO 2 follow the fluctuations in temperature after a short delay, as the product needs time to warm up and cool down. The larger the thermal mass and heat capacity of the product, the slower the product will respond to fluctuations in temperature. This explains why gas levels follow slow temperature fluctuations more clearly than they follow the fast temperature changes. Another reason why gas levels do not follow fast temperature changes is because of the void volume in the package, which buffers the change in gas conditions. The direction of the fluctuation in CO 2 level is the same as for temperature while the direction of the fluctuation in O 2 level is the opposite. As temperature increases, film permeance increases. However, the rate of O 2 consumption increases faster than the increase in film permeance resulting in dropping O 2 levels. With dropping O 2 levels fermentative CO 2 production increases resulting in increasing levels of CO 2 . During the period of fluctuating temperature the same average gas levels are reached as seen before. When temperature is increased to 12oC, the O 2 level drops to 0.5kPa while CO 2 accumulates up to 18kPa due to the fermentation induced. It will be clear that such an increase in temperature to 12oC when a package is designed to operate around 4oC is fatal for the packed product. Depending on the product such temperature increase might irreversibly affect product quality. Packing warm product has the advantage of rapidly establishing the targeted gas conditions. The downside is the induction of condensation as the warm MAP performance under dynamic temperature conditions 569 Fig. 27.1 Simulation results of MA packed shredded lettuce stored at a constant 4oC or at dynamic temperature conditions. (a) Temperature profile used for the dynamic temperature conditions; air temperature (——) and product temperature ( ). (b) O 2 levels observed in the package during different simulation runs. (c) CO 2 levels observed in the package during different simulation runs. (d) Condensation formed during dynamic temperature conditions. The following simulations are depicted in (b) and (c): reference simulation of pre-cooled lettuce packed in polymeric film and stored at a constant 4oC (——), lettuce packed warm using polymeric film and stored at dynamic temperature conditions ( ), lettuce packed warm and stored at dynamic temperature conditions but with a reduced void volume ( . . . . . ), lettuce packed warm using microperforated polymeric film and stored at dynamic temperature conditions ( . – . – . – ). The boxes in (b) and (c) contain an enlargement of what is happening during the period with fluctuating temperatures. 570 Novel food packaging techniques product evaporates more water than the cold air can contain, quickly oversaturating the air with an excess water condensating on the inside of the cold packaging material (Fig. 27.1d). During the subsequent period, con- densation slowly disappears again by evaporation and diffusion through the film. With fluctuating temperatures the amount of condensate fluctuates as well. Once temperature is increased to 12oC there is a fast drop in the amount of condensate. These relative fast changes are due to changes in the air saturation levels for water vapour as a function of temperature. This example shows that condensation can be rapidly induced but once present is hard to remove without increasing temperature again. When the void volume in the package is eliminated (Fig. 27.1b and c) steady state gas conditions are rapidly realised within half a day. Because of the warm lettuce, the CO 2 level peaks to initially extremely high levels, rapidly disappearing when the product cools down. By reducing the void volume we have removed the buffering capacity of the system as a consequence of which the gas levels respond much more vigorously to the fluctuating temperature and also become more sensitive to fast fluctuations. When temperature is increased to 12oC, the increase in CO 2 is much faster than before. When the film is replaced by a microperforated material, permeance of the packaging film has become almost independent of temperature. The resulting gas conditions are now different (Fig. 27.1b and c) with O 2 going towards 3kPa and CO 2 continuing to increase with time. The reason for not reaching steady state conditions is the relatively much lower permeance for CO 2 as compared to the permeance for O 2 . Therefore the steady state conditions for CO 2 are at much higher CO 2 levels than before, which takes more time and the MA package never reaches this situation. Because of the temperature independency of film permeance the fluctuations in O 2 levels respond vigorously to changes in temperature. The final temperature increase to 12oC results in a drop of O 2 to 1kPa and an increase of CO 2 towards 40–50kPa. This increase is clearly the result of fermentative CO 2 production that, due to the low permeance for CO 2 is trapped inside the package. As the accumulating CO 2 has an inhibitive effect on the respiration of lettuce, O 2 consumption is inhibited, resulting in a subsequent slight increase of the O 2 level. The outlined simulations were focused on a single average MA pack. When the dynamic temperature condition is applied to a batch of MA packages, each prepared package will differ slightly from another. Given that biological variance is the most variable parameter, we simulated a batch of 500 packages assuming 25% variation on product respiration rates, and 10% variation on packed product weight and film thickness (Fig. 27.2). The simulation result clearly shows the effect of variation in MA design parameters on the resulting MA gas conditions. At the same time it shows that variation in MA gas conditions depends on time and temperature. As, depending on the respiration rates, some packages establish MA conditions faster than others, initially a large variation in MA gas conditions is observed. Some packages reached a level of 2kPa O 2 within three hours after packing while others took two days to reach MAP performance under dynamic temperature conditions 571 this stage. By reducing the void volume, packing warm product, or flushing the package with nitrogen, the process of establishing MA conditions can be facilitated reducing the initial large variation in MA gas conditions. The variation in O 2 levels is generally much smaller than the variation in CO 2 levels, especially when the temperature increase to 12oC induces fermentation. Under these conditions the high CO 2 levels in some of the packs will induce CO 2 injury. Controlling temperature in such a way that none of the packs develop fermentation would keep the variation in CO 2 levels within limits. 27.5 Maximising MAP performance From the simulations in the previous section it became clear that it is of the utmost importance to prevent all sources of variation, whether that is temperature variation (time but also spatial variation), variation in the product (maturity differences causing variation in respiration rate or variation in the amount of product packed), or variation in the homogeneity of the package itself (variation in thickness, perforations, layers of wrapping, tightness of seal, etc.). Biological variation tends to average itself out when large enough batches of product are packed. The variation between consumer MA packs containing a limited amount of product will be much larger than variation between MA Fig. 27.2 Simulation results of 500 MA packages of shredded lettuce packed using polymeric film stored at dynamic temperature conditions (Fig. 27.1a). The average CO 2 (——) and O 2 levels ( ) are plotted together with their 95% confidence intervals ( . . . . . ). 572 Novel food packaging techniques packed pallets containing a large amount of product per pallet. So increasing the size of MA packages can cope with within-batch variation. Potentially, there is also a large variation related to the maturity of the packed product during the course of the season. As a consequence, early harvested product might have different packaging needs from product harvested later in the season. Ideally, the design of a MA pack is adapted during the season to cope with these changes in maturity. Fine-tuning the design of MA packages to these changing needs during the season can theoretically be done by relatively simple measures as long as one knows what the changing needs of the product are. Close co-operation between product and packaging experts is needed to develop guidelines for the horticultural packaging companies. Variation in the homogeneity of the physical package (variation in thickness, perforations, layers of wrapping, tightness of seal, etc.) is a technical issue that is relatively easy to control during the production process by appropriate quality control. To enable rapid establishment of the intended MA conditions several simple techniques can be applied such as gas flushing the package before sealing. Although this is the most expensive technique, it can establish steady state gas reliably and instantaneously. Packing of warm fruit is the simplest way but comes with the risk of inducing lots of free water in the pack. Depending on how vulnerable the product is to microbial breakdown this might not be an option. Reducing the void volume is the third way of speeding up the process of establishing steady state gas conditions. However, this is not only speeding up the initial process of establishing steady state gas conditions but is increasing the overall responsiveness of the package allowing it rapidly to follow any temperature fluctuations in the logistic chain. Temperature variation can be minimised only by an integral temperature control throughout the whole logistic chain from field to table. It is of the utmost importance to involve all partners in the chain in this integral temperature control as any temperature abuse might nullify the efforts of all other partners. In the end, the success of a chain is determined by the weakest link in the chain. When designing MAP for a certain product one should consider whether the potential benefits are worth the possible risks of a lack of temperature control. If this is questionable, one might consider designing a safe MA system by designing it for the highest temperature likely to be encountered. Although this approach does not utilise the maximum benefits it rules out all associated risks. In the end, MAP can only be successful when good temperature control can be guaranteed. 27.6 Future trends The eventual success of MA depends on temperature control between the moment of packing and the moment of opening of the package by the consumer. Instead of relying solely on one’s gut feeling when optimising MAP, a MAP model to simulate a package going through a logistic chain will give insight into MAP performance under dynamic temperature conditions 573 the strong and weak parts of that chain in terms of temperature control. 12 It will make clear which parts of the chain are responsible for the largest quality losses of the packaged product and need improvement. It enables the optimisation of a whole chain considering the related costs and benefits. To operate such a model, information is needed on temperature, O 2 and CO 2 dependencies of gas exchange and on temperature dependency of film permeance. With regard to the temperature effect on the oxidative respiration of different fruits and vegetables there is some data available. 11 Information on fermentation and on the effects of O 2 and CO 2 on gas exchange is much more fragmentary. This makes it almost impossible to identify at what temperature anaerobic conditions are going to be induced. Also a good database on permeance of packaging films that includes their temperature dependency is lacking. Before a new film can be used for MAP its temperature characteristics need to be identified at temperatures relevant to MAP (0 25oC). To be able to bring MAP to the next level and to predict what the effect of certain dynamic temperature conditions is on a particular MAP design it is vital to establish such databases on product and film characteristics. Without this elementary knowledge, MAP will remain at the level of trial and error. Ultimately, any temperature variation in the logistic chain should be ruled out. Meanwhile, technical solutions like temperature sensitive films are emerging to cope with some of the existing dynamic temperature conditions. 27.7 References 1. BEAUDRY R M, CAMERON A C, SHIRAZI A and DOSTAL-LANGE D L, ‘Modified- atmosphere packaging of blueberry fruit: effect of temperature on package O 2 and CO 2 ’, J. Amer. Soc. Hort. Sci., 1992 117 436–41. 2. BEAUDRY R M, ‘Effect of O 2 and CO 2 partial pressure on selected phenomena affecting fruit and vegetable quality’. Postharvest Biology & Technology, 1999 15 293–303. 3. BEAUDRY R M and GRAN C D, ‘Using a modified-atmosphere packaging approach to answer some postharvest questions: Factors affecting the lower oxygen limit.’ Acta Hort. 1993 362 203–12. 4. BENNIK M H J, Biopreservation in modified atmosphere packaged vegetables, Thesis Wageningen Agricultural University. ISBN 90-5485- 808-7, 1997. 5. CAMERON A C, PATTERSON B D, TALASILA P C and JOLES D W, ‘Modeling the risk in modified-atmosphere packaging: a case for sense-and-respond packaging’, in: Blanpied. G D, Bartsch, J A and Hicks, J R (eds), Proc. 6th Intl. Controlled Atmosphere Research Conference, Ithaca NY, 1993. 6. CHAMBROY Y, GUINEBRETIERE M H, JACQUEMIN G, REICH M, BREUILS L and SOUTY M, ‘Effects of carbon dioxide on shelf-life and post harvest decay of strawberries fruit’, Sciences des Aliments, 1993 13 409–23. 7. CHEN X Y, HERTOG M L A T M and BANKS N H, ‘The effect of temperature on 574 Novel food packaging techniques gas relations in MA packages for capsicums (Capsicum annuum L., cv. Tasty): an integrated approach’. Postharvest Biology & Technology, 2000 20 71–80. 8. COLELLI G and MARTELLI S, ‘Beneficial effects on the application of CO 2 - enriched atmospheres on fresh strawberries (Fragaria ananassa Duch.).’ Adv. Hortic. Sci., 1995 9 55–60. 9. EXAMA A, ARUL J, LENCKI RW, LEE L Z and TOUPIN C, ‘Suitability of plastic films for modified atmosphere packaging of fruit and vegetables.’ J. Food Sci., 1993 58 1365–70. 10. GIL M I, HOLCROFT D M and KADER A A, ‘Changes in strawberry anthocyanins and other polyphenols in response to carbon dioxide treatments.’ J. Agric. Food Chem. 1997 45 1662–7. 11. GROSS, K C, WANG C Y and SALTVEIT M E, ‘The Commercial Storage of Fruits, Vegetables, and Florist and Nursery Crops.’ An Adobe Acrobat pdf of a draft version of the forthcoming revision to US Department of Agriculture, Agriculture Handbook 66 on the website of the USDA, Agricultural Research Service, Beltsville Area <http://www.ba.ars. usda.gov/hb66.html> (November 8, 2002). 12. HERTOG M L A T M, PEPPELENBOS H W, TIJSKENS L M M and EVELO R G, ‘Modified atmosphere packaging: optimisation through simulation’, in: Gorny, J R (ed.), Proc. 7th Intl. Controlled Atmosphere Research Conference, Davis CA, 1997. 13. HERTOG M L A T M, BOERRIGTER H A M, VAN DEN BOOGAARD G J P M, TIJSKENS L M M and VAN SCHAIK A C R, ‘Predicting keeping quality of strawberries (cv. ‘Elsanta’) packed under modified atmospheres: an integrated model approach.’ Postharvest Biology & Technology, 1999 15 1–12. 14. KE D, GOLDSTEIN L, O’MAHONY M and KADER A A, ‘Effects of short-term exposure to low O 2 and high CO 2 atmospheres on quality attributes of strawberries.’ J. Food Sci. 1991 56 50–4. 15. LOPEZ-GALVEZ G, SALTVEIT M E and CANTWELL M, ‘The visual quality of minimally processed lettuce stored in air or controlled atmospheres with emphasis on romaine and iceberg types.’ Postharvest Biology & Technology, 1996 8 179–90. 16. SMOLANDER M, HURME E and AHVENAINEN R, ‘Leak indicators for modified-atmosphere packages.’ Trends in Food Science & Technology, 1997 8 101–6. 17. SMYTH A B, SONG J and CAMERON A C, ‘Modified atmosphere packaged cut iceberg lettuce: effect of temperature and O 2 partial pressure on respiration and quality.’ J. Agric. Food Chem. 1998 46 4556–62. 18. YEARSLEY C W, BANKS N H and GANESH S, ‘Temperature effects on the internal lower oxygen limits of apple fruit.’ Postharvest Biology & Technology, 1997 11 73–83. MAP performance under dynamic temperature conditions 575 absorbers see scavengers absorption 22, 144–5 see also packaging-flavour interactions absorption-type antimicrobial packaging 51 acetaldehyde scavengers 514 acetate buffer 392 acetic acid 129, 298–9 acid tolerance response (ATR) 250–1 Actipak study 6, 13, 459, 460, 461–8 classification of active and intelligent systems 461–5 inventory 461 microbiological safety and shelf-life extending capacity 465–6 recommendations for legislative amendments 467–8 toxicological, economic and environmental evaluation 466–7 activated carbon scavengers 38, 39, 41 activation energy 347 active packaging 2, 6, 337–8, 459–60 antimicrobial packaging see antimicrobial packaging classification 461–5 and colour control see colour control consumers and see consumers current research 13 current use 12 fish see fish future trends 16–17 integrated active packaging, storage and distribution 5, 18, 204, 535–49 legislation see legislation meat see meat NMBP see non-migratory bioactive polymers scavengers see scavengers scope 469 techniques 6–11 activity locus of 74–5, 77–8 reduced 78 specific activity 60 adsorption 22, 144–5 clay 175, 176 irreversible 179–80 molecular sieves 177–8 silica gel 173, 174, 175 adsorption capacity 184–5 adsorption rate 185 aerobic bacteria 23–5 Aeromonas hydrophila 212–14, 237–8, 250, 290 species 212–14, 235 aflatoxin 24 Ageless absorbers 29, 42, 280, 388, 389–90 agricultural production practices 252, 255 Air Liquide 191–2 air pressure 537–8 Index alarm systems 540–1 alcohol dehydrogenase 93 alcohol oxidase 30 aldehydes 165 absorbers 8, 43, 393–4 algae 320 alginates 393 alpha-tocopherol (vitamin E) 44 ambient moisture 181 Ambitemp indicator 108 amines 165 absorbers 8, 43, 393–4 biogenic 130–1, 137 amino-cyclopropane carboxylic acid (ACC) 35 ammonia 130 Amosorb oxygen scavenger 32 amylopectin 522 anaerobiosis 221 ANICO bags 43, 165, 394 anthocyanins 220, 417, 426–7, 429 degradation 422–3 antibiotics 56, 57 anti-browning agents 432 antimicrobial agents 52–8 carbon dioxide 208–10, 387 naturally occurring 244 antimicrobial dipping 245–7, 253 antimicrobial packaging 8–11, 16, 50–70 factors affecting effectiveness 60–4 fish 391–2, 395–6 NMBP 92–4 system construction 58–60 antimicrobial preservative releasers 8, 9 antioxidant releasers 9 antioxidants 57, 392 Apack trays 531 APNEP system 87 apolar polymers 164–5 appearance 366–8 see also colour control applicability of TTIs 111 argon MAP 191–2, 431, 480 testing 193–6 Arrhenius equations 163, 347, 348 Arun Foods Ltd 202–3 ascorbate oxidase 216, 218 ascorbic acid (AA) 30–1, 216–18, 432 Aspergillus parasiticus 23–4 ATP degradation products 131 Australia 12, 14–15 Auto-ID Center 544 automatic identification 542 availability of technology 79 Bacillus cereus 241, 289–90 subtilis 333, 334 bacteria 320 aerobic 23–5 LAB 231, 249–50, 255, 300–1, 370–1, 386 spore-forming 293–4 see also microorganisms bacteriocins 54, 57, 292, 300–1 bananas 536–7 barium oxide 180 barrier layers 26 barrier properties 153–6 barriers, functional 509–12 beef 404–8, 411 Bentonite 174 benzoic acid 297, 393 benzophenone 506–7 ‘best before’ date 558–9 beta-carotene 218 betalains 417 bioactive materials 71 see also non-migratory bioactive polymers biocides 483–4 biodegradable packaging materials 519–34 current applications 529–33 developing novel materials 524–6 future trends 533 legislative issues 526–9 problem of plastic packaging waste 519–20 range of biopolymers 520–4 biogenic amines 130–1, 137 Bioka 30 biological variation 345–6, 350–1, 356, 572–3 biomimetic antimicrobial polymers 83–4 Biopol 523, 531–2 biopolymers see biodegradable packaging materials biosensors 95, 137 biphenyl 484 bone 367 bottle closures 33 bound moisture 182 Brassica vegetables 221–2 Brochothrix thermosphacta 386 bromothymol blue 134 browning 220, 221, 423–4, 425, 428, 430 inhibitors 432 bulk MAP 374–5 Index 577 bulk modification 85–6 bulk transport 483 butylated hydroxytoluene (BHT) 392 cadaverine 130–1 calcium hydroxide (slaked lime) 42, 179 calcium oxide (quicklime) 179–80 calcium sulphate 179 calicivirus 239, 247 Campylobacter jejuni 235, 238–9, 241 capillary condensation 184 carbodiimide coupling method 89–90 carbohydrates 151–2 carbon dioxide 94, 190, 279, 480 absorption in meat 403 CAP for meat products 376–7 generation inside package 300, 387 high carbon dioxide and colour stability of fresh produce 426–8, 429–31 and dynamic temperature conditions 567, 569–72 high oxygen MAP 197–8 indicators 11, 282 MAP and food preservation 312, 313 MAP for meat products 372, 373–4 and microbial growth 131, 208–10, 248, 372, 387 pH change indicator 134 pH and solubility of 298 SGS 300, 387 carbon dioxide emitters 9, 387, 388–90 carbon dioxide scavengers 7, 41–2 carbon monoxide 367–8, 372–3, 374, 375–6, 379, 431 carboxymyoglobin 366, 368, 375–6 carotenogenic fruits 420 carotenoids 218–19, 417 casting methods 63 catechol oxygen scavenging sachets 30 catecholases 423 cellular penetration 209 cellulose acetate (CA) 43 certification procedure 474, 475 challenge test 504–5 cheese slices 449–50, 451, 452 chicken balls 454–6 chicken legs, raw 450–4 chitosan 55, 57, 80–2, 393 chlorine 245–7 chlorine dioxide 58 chlorophyll 417, 427–8 degradation 419–22 chloroplasts 417, 420 cholesterol reductase 91–2 cholesterol remover 8 chroma 418, 424 chromoplasts 417, 420 CIELAB colour measurement system 418 citric acid 298–9 clay moisture regulation 172, 174–6 starch-clay nano-composites 524–6, 527 climacteric fruits 420 Clostridium botulinum 240, 250 fish 395–6 measuring pathogen risks 235, 236 microbial safety of MAP 210–11 oxygen scavengers and 24–5 preservation technologies 289–90 coffee 41 collagen sausage casings 533 colorimeters 417–18 colorimetric nose 138 colour control fruit and vegetables 416–38 colour changes and stability 349, 417–18 colour measurement 418–19 colour stability and MAP 424–6 combining low oxygen, high carbon dioxide and other gases 429–32 future trends 423 high carbon dioxide effects 426–8 process of colour change 419–24 meat 401–15 cured meat 409–10, 410, 411–12, 414 factors affecting colour stability 371, 402–3 fresh meat 404–8, 411, 412, 413 future trends 412–14 modelling impact of MAP 403–10 pre- and post-slaughter factors 410–12 colours 480–1 combined preservation techniques 287– 311 combining MAP with other techniques 288–93 consumer attitudes 301–2 future trends 302–3 heat treatment and irradiation 292, 293–6 hygienic conditions 291–3 Na 2 CaEDTA 299–300 578 Index preservatives 292, 297–9 protective microbes and bacteriocins 300–1 soluble gas stabilisation 292, 300 specific groups of microorganisms 289–91 combined UV/ozone systems 317–18, 327–32, 335–6 compostability 526–8 computer simulations see modelling concentration 147–8 condensation 181, 568, 569–72 consumers 15–16, 550–62 attitudes towards combining MAP with other technologies 301–2 attitudes towards novel packaging 555–9 convenience and optimization 443, 447, 448–9, 449–58 and future of novel packaging 559–62 general attitudes 555–6 methods for testing responses 552–5 new packaging technologies and 550–1 problems in testing responses 551–2 segments and behaviour 547 contamination levels, and recycling 500–3 controlled atmosphere packaging (CAP) 365, 378–9 meat products 376–7 controlled release 60–1, 63, 64 corona discharge (CD) 87, 321–2 costs indirect packaging costs 448, 448–9, 449–58 NMBP 79 package optimization 443, 447–8, 448–9, 449–58 TTIs 111 coupling chemistries 88–90 critical temperature indicators (CTIs) 105, 107, 108 critical temperature/time integrators (CTTIs) 105, 107, 108 Cryovac OS1000 32 Cryptosporidium parvum 241, 242, 247 crystallinity 146–7 cured meat 410, 411–12, 414 ham 409–10 Cyclospora cayetanensis 241, 242 cysts, parasitic 241, 242, 247, 320 dairy products 92–3, 449–50, 451, 452, 510–11 dangerous substances 490 Darex oxygen scavenging technology 33 date marks 485, 486, 487, 558–9 dedicated MAP models 351–2 dedicated tests 477 degreening 420, 421 dehydroascorbic acid (DHA) 216–18 demonstrations 560 deoxymyoglobin 366, 367 desiccants see moisture regulation destructive leak test methods 277 destructurised (thermoplastic) starch 522, 526, 527, 530 dew point 181 diacetyl 135 diffusion 77–8, 145, 163 meso-level modelling 340–1, 342, 347–8 micro-level modelling 342–4, 349 diffusion-based TTIs 108–9 dimensioning MAP 352–3 dimethylamine 130 dinitrogen oxide see nitrous oxide MAP dipping, antimicrobial 245–7 discolouration 371 disinfectants 245–7 disintegration test 528–9 distance 537–8 distribution 63 and butchering of meat 377–9 integrating active packaging, storage and 5, 18, 204, 535–49 monitoring shelf-life during 112–16 optimization using TTIs 116–21 package leak indicators during 279–82 reducing pathogen risks 254, 255–6 ‘do not eat’ symbol 489–90 drying 172 recycling processes 505–6 see also moisture regulation dynamic temperature conditions 563–75 future trends 573–4 impact on MAP performance 568–72 maximising MAP performance 572–3 temperature control and risks of MAP 566–8 EAN UCC 544–5 economic evaluation 467 edible coatings 255 antimicrobial packaging and 59–60, 61 chitosan 81–2 fish 392–3 elasticity, modulus of 146, 147 electrochemical sensors 323, 324 electronic article surveillance (EAS) tags 541, 542 Index 579 electronic field date recorders 537 electronic labelling 17, 138, 541, 542 electronic nose 137–8, 513 Enterobacteriaceae 249 environment evaluation in Actipak study 467 green plastics see biodegradable packaging materials packaging waste legislation 491–2 stresses and package optimization 443, 444, 446–7, 448–9, 449–58 enzymatic TTIs 109, 110 enzyme-based oxygen scavengers 30 enzymes 53–4, 71, 209 see also non-migratory bioactive polymers equilibrium modified atmosphere (EMA) 190 Escherichia coli (E. coli) 80, 240 factors affecting survival 242–3, 246, 250 indicator 136 measuring pathogen risks 235, 237 new germicidal techniques 324–5, 332, 333, 334 essential oils 292, 299, 392 ethanol antimicrobial agent 56, 57, 58, 94 indicator of freshness 129–30, 135 ethanol emitters 9, 12, 391 equilibrium relative humidity (ERH) 182 ethylene 344–5, 421–2 ethylene scavengers 7, 12, 34–41, 561 economic aspects 41 measuring ethylene sorption 40 principle of ethylene sorption 37–40 role of 34–7 European Union 12 ILSI document 515 legislation see legislation recycling projects 514 RFID research 545 EVOH (ethylene vinyl alcohol) 25 experimental designs 555 external indicators 11 extrusion 63, 525 exudate losses 369 facultative anaerobes 247–8, 370–1 fat 150–1, 152–3 fermentation threshold 566 Fick’s law 347 films with antimicrobial properties 8–11 choice for MAP 327, 373 developing new films 353 gas impermeable 376 microperforated 190, 567, 571 multilayer PET 511–12 oxygen scavenging 31–3 perforated 347, 567 permeability 347, 353, 356, 402–3 Finland 538–40 First In First Out (FIFO) system 116, 118–20, 121 fish 384–400 active packaging antimicrobial and antioxidant applications 391–2 atmosphere modifiers 387–90 edible coatings and films 392–3 taint removal 393–4 water control 390–1 future trends 395–6 intelligent packaging applications 394–5 microbiology of fish products 385–7 monitoring shelf-life 113–15 flame treatment 87 flavonoids 219, 220 flavour absorbers of off flavours 8 control 368–9 packaging-flavour interactions see packaging-flavour interactions flavour absorption factors affecting 145–9 modelling 160–4 flavour modification 156–8 flavour-releasing materials 9, 44, 482, 561 flavouring substances 482–3 Flory-Huggins theory 160 flow pack machines 198, 325–6 fluorescent dye 281 foamed polymer packaging 530–1 focus group discussions 553 food additives European legislation 478–81, 487 US regulations 75–6 food contact materials (FCM) 460, 470–8, 529 basic rules for migration tests 474–8 Framework Directive 470–1 plastics directives 472–4 symbol for 471–2 Food and Drug Administration (FDA) 504, 514–15 580 Index Food Hygiene Directive 485–7 Food Imitation Directive 490–1 food matrix 149–53 food poisoning hazards 314 food safety see safety Food Sentinel System 136 food spoilage see spoilage foodborne infections 232–3, 240–1 form-fill-seal machines 198, 325–7 free volume 146 freezing 294–5 fresh meat 411, 412, 413 beef 404–8 fresh produce 1 colour control see colour control effect of MAP on nutritional quality 215–22 novel MAP applications 189–207 future trends 202–4 high oxygen MAP 196–202 novel MAP gases 191–2 testing 193–6 reducing pathogen risks 231–75 factors affecting pathogen survival 242–51 future trends 254–6 improving MAP 251–4 measuring pathogen risks 232–42 supply chain 535–8 Fresh-Check 109–10 Freshilizer 29 FreshLock 42 FreshMax 33 Freshness Check 108 freshness indicators 11, 17–18, 127–43, 565 biosensors 137 compounds indicating quality 128–32 electronic nose 137–8 future trends 138 pathogen indicators 11, 17–18, 134, 136, 395, 396 types of 132–6 Freshness Monitor 109–10 FreshPad 10 FreshPax 29–30 FreshTag 135, 395 Frisspack 38 frozen foods 115–16 fruit juices 43, 156–8 fruit and vegetables see fresh produce functional barriers 509–12 functionalisation of polymers 79, 85–8 fungi 194, 195 fungicides 54, 57 gas composition colour stability of fresh produce 429–32 colour stability of meat 402–3 high oxygen MAP 197–8 pathogen survival 247–8 gas diffusion meso-level modelling 340–1, 342, 347–8 micro-level modelling 342–4, 349 gas exchange 356, 402–3 meso-level modelling 341, 342 micro-level modelling 341, 348, 349 gas flushing 573 gas indicators 565 carbon dioxide 11, 282 oxygen 11, 280–2 gases absorption in meat 403 antimicrobial agents 56, 58 EU legislation and packaging gases 480 MAP for fish 387–90 novel MAP gases 191–2 SGS 292, 300, 387–8, 388–90 see also under individual gases GEMANOVA model 405–8 general attitude studies 555–6 Germany 515 germicidal techniques 312–36 future trends 332–6 installation of UV/ozone systems 327–32 integration with MAP 325–32 new 314–15 ozone 315, 321–5 ultraviolet radiation 314–15, 315–20 Giardia lamblia 241, 242 glass transition temperature 146, 147 glucalase 30 glucose 129, 136 glucose oxidase 30, 93, 393 glucosinolates 221–2 glutaraldehyde coupling 89 good agricultural practices (GAP) 252, 255 good manufacturing practices (GMP) 252, 252–3 grapefruit juice 43 green plastics see biodegradable packaging materials growth seasons 535–7 GTAG 544 gypsum 179 Index 581 Hafnia alvei 250 ham, cured 409–10 ham pizza 457–8 Hazard Analysis and Critical Control Point (HACCP) system 103, 252, 253, 254, 485 headspace gas composition see gas composition heat stress response 250–1 heat transfer 339, 346–7 heat treatment 292, 293–4, 303 helium 279, 480 hepatitis A viruses (HAV) 239, 241, 291 hexamethylenetetramine 56 high density polyethylene (HDPE) 498–9, 502–3, 530 monolayer bottles 512–13 high impact polystyrene (HIPS) 512 high oxygen MAP 189–90, 191, 192 applying 196–202 fresh produce applications 201–2 future trends 202–4 optimal gas levels 197–8 packaging materials 199–201 produce volume/gas volume ratio 198–9 safety 197 temperature control 201 testing 193–6 histamine 130–1 homeostasis 289 horizontal form-fill-seal (HFFS) machines 198, 325–6 hot-fill conditions 508, 568, 569–72, 573 hue angle 418, 424 humectant salts 178–9 humidity 538 modelling MAP 341, 344, 349, 356 relative 149, 181, 184 temperature control and risks of MAP 567–8 see also moisture regulation; water humidity absorbers see moisture absorbers hurdle technology 51, 52, 289 hydration, water of 179 hydrogen 279 hydrogen sulphide 131–2, 135 hydroxypropyl cellulose 393 hygiene 254 combining MAP with other preservation technologies 291–3 European legislation 485–7 I-Point indicator 108, 109 imitation, food 490–1 immobilisation-type antimicrobial packaging 51–2 immobilised bioactive-type polymers 84–95 antimicrobial packaging/shelf-life extension 92–4 applications 90–5 developing NMBP by immobilisation 85–90 in-package processing 90–2 intelligent packaging 94–5 in-house control 541 in-package processing 90–2 incineration, suitability for 447, 448–9, 449–58 indigenous microflora 244, 249–50 indirect packaging costs 448, 448–9, 449–58 information 560 information banks 547 inherently bioactive synthetic polymers 79–84 chitosan 80–2 UV irradiated nylon 10, 82–3 insect damage 23 insulating materials 10 integrated active packaging, storage and distribution 5, 18, 204, 535–49 alarm systems and TTIs 540–1 future trends 545–7 role of packaging in supply chain 538–40 supply chain for perishable foods 535–8 traceability 18, 542–5, 546 intelligent packaging 2, 6, 459–60 classification 461–5 consumers and see consumers current research 13 current use 12 fish 394–5 freshness indicators see freshness indicators future trends 17–18 integrating active packaging, storage and distribution 5, 18, 204, 535–49 leak detectors see leak detectors legislation see legislation NMBP 94–5 pathogen indicators 11, 17–18, 134, 136, 395, 396 582 Index scope 469 technologies 11–12 TTIs see time-temperature indicators internal indicators 11 Internet 545–6 interviews 553–4 ionising radiation (irradiation) 255, 292, 295–6, 302 invisible oxygen indicators 281 iron-based oxygen scavengers 27–30, 388 irradiation (ionising radiation) 255, 292, 295–6, 302 ISO 9000:2000 quality management standard 103 Japan 12, 14 kimchi 41, 42 kinetic modelling 113–16 labelling 302 European legislation 471, 481, 485, 487–9, 489–90 labels 8 oxygen scavenging 33 lactase-active packaging 8, 77, 90–1 lactic acid 129, 298–9, 521 lactic acid bacteria (LAB) 231, 249–50, 255, 300–1, 370–1, 386 lactoperoxidase system of milk 92–3 lactose-free milk 77, 90–1 lactose remover 8 leak detectors 276–86 detection during processing 277–9 future trends 282–3 indicators during distribution 279–82, 561 leakage, product safety and quality 276–7 Least Shelf-Life First Out (LSFO) system 116–20, 121 legislation 13–15, 200 Australia 14–15 European 15, 75, 459–96 Actipak study 6, 13, 459, 460, 461–8 biocides and pesticides 483–4 biodegradable plastics 526–9 current legislation and recommendations for change 468–70 food additives 478–81, 487 food contact materials 460, 470–8 food flavouring 482–3 food hygiene 485–7 food labelling 471, 481, 485, 487–9, 489–90 initiatives to amend 461–8 Nordic report 460, 468 product safety and waste 489–92 Japan 14 USA 14, 75–6 lettuce, shredded 568–72 lidded trays 375 light bacteria deactivation 332–3, 334 exposure and colour stability of meat 405–7 light-activated oxygen scavenging films 31–2 limonene 157–8, 501–2, 503, 510–11 limonin 43, 165 Lifelines Freshness Monitor 109–10 lipase 424 lipid oxidation 368–9, 392 modelling 162–4 packaging-flavour interactions 159, 162–4 lipoxygenase 424 Listeria monocytogenes 240, 289–90, 395 factors affecting survival 242, 245–6, 248, 249, 251 measuring pathogen risks 233–6 microbial safety of MAP 211–12 LLDPE film 159 locus of activity 74–5, 77–8 logistics optimizing logistic chains 353–4 performance and packaging optimization 442–3 low density polyethylene (LDPE) 154, 155, 157, 158, 498, 530 low-pressure mercury vapour lamp 317 low temperature preservation 292, 294–5, 396 luminescent dyes 281 lycopene 218–19 lysozyme 92 macro-level modelling 339, 346–7 magnesium chloride 178 magnesium oxide 180 malic acid 298–9 marketing 76 properties and packaging optimization 443, 447, 448–9, 449–58 marking/tagging 18 Index 583 mass transfer 144–5, 339, 346–7 meat 1 active packaging 365–83 CAP 376–7 control of appearance 366–8 delaying microbial spoilage 369–71 flavour and texture 368–9 future trends 377–9 MAP technology 372–6 temperature and storage life 371–2 colour control see colour control consumer attitudes towards novel packaging 557, 558 mechanical integrity 63–4 mechanical strength 446, 448–9, 449–58 mechanisms of action 78 mechanistic models 355 membranes, cell 210 melanins 220 mercury lamp, low-pressure 317 meso-level modelling 340–1, 342, 347–8 methyl cellulose 393 metmyoglobin 366, 367, 368 metmyoglobin reduction activity 366–7 Michaelis Menten approach 348 microaerophilic microorganisms 247–8 micro-level modelling 341–6, 348–51 microorganisms 36 Actipak study and safety 465–6 combining MAP with other preservation technologies 287–301 fish 385–7, 395–6 growth kinetics 60–1 integrating MAP with new germicidal techniques see germicidal techniques meat delaying microbial spoilage 369–71 temperature and storage life 371–2 mechanisms of carbon dioxide inhibition 208–10, 387 microbial growth indicators see freshness indicators modelling MAP 345, 350 novel MAP applications for fresh produce 191, 192, 193–5 pathogen risks see pathogen risks safety of MAP 210–14 microperforated films 190, 567, 571 microwave heating modifiers 10 microwave susceptors 10 microwave UV lamps 317–18, 327–32, 335–6 migration 144–5 evaluation and recycling 507–8 from oxygen scavengers and moisture absorbers 461–2, 463 see also packaging-flavour interactions migration limits 460, 472, 529 migration tests, basic rules for 474–8 milk 92–3 milk bottles 512–13 milk products 510–11 minerals, finely dispersed 38–40, 41 minimal processing 252–3 and pathogen survival 244–7 and stress responses 250–1 minimum durability dates 485, 486, 487, 588–9 MINIPAX sachet 44, 394 misuse of plastics 500–3 mixing 77–8 mixtures of flavour compounds 147–8 modelling 337–61 advantages and disadvantages of models 354–5 applying models to improve MAP 352–4 current MAP-related models 346–51 dedicated models 351–2 dynamic changes in headspace gas composition 402–3 flavour absorption 160–4 future trends 356 impact of MAP and colour stability in meat 403–10, 412–13 macro-level 339, 346–7 meso-level 340–1, 342, 347–8 micro-level 341–6, 348–51 migration 507–8 principles and methods 338–46 modified atmosphere packaging (MAP) 12, 22–3, 365 colour stability in fresh produce 424–32 combining with other preservation techniques 287–311 defining MAP performance 564–6 dimensioning 352–3 and food preservation, food spoilage and shelf-life 312–14 gases see gas composition; gases improving through modelling 337–61 integrating with new germicidal techniques 312–36 leak detection 276–86 novel applications for fresh produce 189–207 packaging optimization 449–58 584 Index performance under dynamic temperature conditions 563–75 product safety and quality 208–30 reducing pathogen risks 231–75 technologies for meat products 372–6 modulus of elasticity 146, 147 moisture 537–8 ingress 182–3 sources in packaging 181–3 see also humidity; moisture regulation; water moisture absorbers 7, 477, 489 fish 390–1 migration from 461–2, 463 moisture regulation 172–85 clay 172, 174–6 fish 390–1 future trends 185 humectant salts 178–9 irreversible adsorption 179–80 molecular sieves 172, 176–8 planning a moisture defence 180–5 selection of desiccant 183–5 silica gel 173–4, 175 moisture vapour transmission rate (MVTR) 182–3 molecular sieves 172, 176–8 molecular size 148 molecular structure 148 Monitor Mark TTI 108–9 monolayer recycled plastics 512–13 monolithic system 62–3, 64 Monte Carlo simulation 118–20, 350–1 Montmorillonite 174, 176 moulds 231, 320 oxygen scavengers and 23–5 multilayer adsorption 184 multilayer PET 511–12 Multivac Rollstock machine 326–7 mycotoxins 23–4 myoglobin 135, 366–8, 404, 411 Na 2 CaEDTA 299–300 nano-composites 524–6, 527 naringin 90, 165 native starch 522 natural extracts 55, 57–8 naturally occurring antimicrobials 244 Nature Works PLA 521, 532 nisin 301 nitric oxide 431–2 nitrite 411–12, 414 nitrogen 190, 313, 373, 374, 376, 480 nitrogen compounds, volatile 130, 135 nitrous oxide MAP 191–2, 480 testing 193–6 noble gases 431 non-climacteric fruits 420 non-destructive package leak testing 276, 277–9 non-migratory bioactive polymers (NMBP) 71–102 benefits 72–7 food processor’s perspective 77 marketing aspects 76 regulatory advantages 75–6 technical 72–5 current limitations 77–9 future trends 95 inherently bioactive polymers 79–84 polymers with immobilised bioactive compounds 84–90 applications 90–5 non-respiring food products 215 Nordic report 460, 468 Norwalk virus 239, 241 nutritional quality see quality nylon, UV irradiated 10, 82–3 odour scavengers 8, 42–4, 393–4 off flavours, absorbers of 8 oil 150–1, 152–3 one-sided contact 476–7 optimization 2, 5, 441–58 examples of 449–58 improving decision-making 458 issues in 442–4 VTT Precision Packaging Concept 444–9 Orega bag 40 oregano essential oil 299 organic acids 53, 57, 129, 298–9 orientated polypropylene (OPP) 199–200 overall migration limit 460, 472, 529 Oxbar 33 oxidation lipid oxidation see lipid oxidation prevention by oxygen scavengers 23 oxygen 312, 313, 480 barrier films 199–200 and growth of Listeria monocytogenes 212 high oxygen MAP see high oxygen MAP indicators 11, 280–2 low oxygen MAP colour stability of fresh produce 424–6, 429–31 Index 585 oxygen (cont.) dynamic temperature conditions 566–7, 569–72 meat appearance 366–7 colour stability 404–8, 409–10 MAP technology 372, 374 permeability 26, 153–6 oxygen emitter/carbon dioxide scavenger dual action sachet 203 oxygen scavengers 7, 12, 22–34, 56, 481 consumer acceptance 556–7 economic aspects 33–4 fish 387, 388–90 meat 377, 378 migration from 461–2, 463 role of 23–5 selection of right type of 25–34 Oxyguard 32 oxymyoglobin 366, 367 Oxysorb 30–1 ozone 315, 321–5 combined UV/ozone systems 317–18, 327–32, 335–6 future trends 332–6 integration with MAP 327–32 PA 530 package integrity 276 see also leak detectors package weight/product weight ratio 446, 448–9, 449–58 packaging: role in supply chain 5–6, 538–40 packaging-flavour interactions 144–71 and active packaging 164–6 factors affecting flavour absorption 145–9 flavour modification and quality 156–8 lipid oxidation 159, 162–4 modelling flavour absorption 160–4 role of differing packaging materials 153–6 role of food matrix 149–53 packaging gases see gas composition; gases packaging materials green plastics see biodegradable packaging materials high oxygen MAP 199–201 improving MAP to reduce pathogen risks 253–4 recycling see recycling role in packaging-flavour interactions 153–6 waste see waste packaging optimization see optimization palletised packs 339, 346–7 palmitates 393 Paperfoam 531 parasites 241, 242, 247, 320 partial freezing 294–5 partition coefficients 161–2 passive MAP 338 pathogen indicators 11, 17–18, 134, 136, 395, 396 pathogen risks 231–75 factors affecting pathogen survival 242–51 future trends 254–6 improving MAP to reduce 251–4 measuring 232–42 see also microorganisms peptides 71 see also non-migratory bioactive polymers perforated films 347, 567 permeability 204 films 347, 353, 356, 402–3 modelling dynamic changes in headspace gas composition 402–3 oxygen 26, 153–6 permeability coefficient 183 permeability rate 183 permeation 144–5 see also packaging-flavour interactions peroxidases 424 pesticide emitters 9 pesticides 484 pH 209, 244, 292, 298 freshness indicators sensitive to pH change 132–4 phenolic compounds 219–21 pheophytin 420–1 Photobacterium phosphoreum 386–7 photodiode 318–19 physical integrity 63–4 pichit film 391 pigment composition 418–19 pizza 457–8, 557 plasma processing 87–8 plaster of paris 179 plastics directives 472–4, 475 packaging-flavour interactions see packaging-flavour interactions recyclability of 498–500 see also recycling 586 Index polarity 148, 161–2 polyalkylene imine (PAI) 43 polycaprolactone 523, 530 polycarbonate (PC) 153, 154, 155, 158 polyesters 148, 165 synthetic 523, 530 polyethylene (PE) 153 polyethylene glycol (PEG) 84, 88 polyethylene naphthalate (PEN) 498–9 polyethylene terephthalate (PET) 530 packaging-flavour interactions 153, 154, 155, 156, 158 recycling 492, 497, 498–9, 500–3, 513 monolayer bottle 512 multilayer PET bottles 511 multilayer PET films 511–12 testing safety and quality 505–8 polyhydroxyalkanoates (PHAs) 523, 531–2 polylactic acid (PLA) 84, 520, 521, 530, 532 poly-1–lysine 84 polymer-based TTIs 109–10 polymeric spacers 88 polymers antimicrobial 55, 57 apolar 164–5 NMBP see non-migratory bioactive polymers swelling 86 polyolefins 148 polyphenol oxidase (PPO) 191, 192, 196, 220, 422–3, 423 polypropylene (PP) 153, 154, 155, 498, 530 three-layered PP cups 510–11 polystyrene (PS) 498–9, 530, 530–1 polyunsaturated fatty acids (PUFAs) 31 polyvinyl chloride (PVC) 498–9 polyvinylalcohol (PVOH) 523–4, 531 polyvinylidene chloride (PVDC) 26, 199–200 positive lists 460, 472 potassium permanganate scavengers 37–8, 39, 41 potassium sorbate 297, 392 poultry products 1, 368, 450–6 preformed tray and lidding film (PTLF) machines 198 preservation 1, 5–6 combining MAP with other preservation techniques 287–311 MAP and 312–14 traditional methods 51 preservatives 292, 297–9 pressure differential leak testing 278 processing 77 minimal 244–7, 250–1, 252–3 package leak detection during 277–9 reducing pathogen risks 255–6 product/headspace volume ratio 198–9, 409–10 Profresh sachet 394 protective microbes 244, 300–1 see also lactic acid bacteria proteins 71, 532–3 see also non-migratory bioactive polymers protozoan parasites 241, 242, 247, 320 provitamin A carotenoids 218–19 Pseudomonas aeruginosa 80, 332 species 249–50, 370 psychotrophic microorganisms 247–8, 450 pulsed UV light 333–5 putrescine 130–1 qualitative consumer testing 552–3, 553–4 quality 208–30, 303 compounds indicating 128–32 effect of MAP on nutritional quality 215–22 fresh produce 215–22 non-respiring food products 215 extending quality of fish 396 freshness indicators see freshness indicators improving MAP through modelling 345, 355, 356 intelligent packaging techniques 11–12 leakage, product safety and 276–7 packaging-flavour interactions and 156–8 quantitative consumer testing 553, 553–5 questionnaires 554 quinones 220 radio frequency identification (RFID) 542–5, 546 standardisation 543–4 ready meals 1–2, 293–4, 396 recovery 491, 492, 528 recycling 491, 492, 497–518, 528 conventional recycling processes 505–6 direct contact applications 512–13 future trends 513–14 Index 587 recycling (cont.) indirect contact applications 509–12 recyclability of packaging plastics 498–500 recyclability of plastic packaging 500–4 super-clean processes 503–4, 506–7 technology 503–4 testing safety and quality of recycled material 504–9 using recycled plastics in packaging 509–13 redox indicators 26, 280 reducing compounds 280 regeneration of silica gel 173–4 regulation 64, 75–6 see also legislation relative humidity 149, 181, 184 release-type active packaging systems 6–8, 9 release-type antimicrobial packaging 51 reliability 111 remelting 506 research 13, 256 respiration 35–6, 190 respiration rate 204 ripening 35–6, 349–50 roasted chicken balls 454–6 sachets 8 oxygen scavenging 27–31 safety 76, 208–30, 288, 303, 481 consumers and 560–1 European legislation 489–92 high oxygen MAP 197 leakage and 276–7 microbial safety of MAP 210–14 ‘Safety and Information in Packaging’ programme 538–40 Safety Monitoring and Assurance System (SMAS) 122 Salmonella species 235, 238, 240, 242–3, 246, 250, 290 typhimurium 80 salt (sodium chloride) 172, 178, 292, 297–8 scavengers 6, 7–8, 22–49 carbon dioxide 7, 41–2 ethylene see ethylene scavengers future trends 44–5 moisture see moisture absorbers odour 8, 42–4, 393–4 oxygen see oxygen scavengers seasons, growth 535–7 security tags 17, 138 self-cooling cans/containers 10 self-heating cans/containers 10 sensitivity studies 354 sensory quality see quality sensory testing 508–9 shape 490 shelf-life 303, 485 Actipak study and extending capacity 465–6 antimicrobial packaging and extension of 92–4 high oxygen MAP and extending 203 MAP and food preservation 312–14 novel MAP applications and fresh produce 193, 194 packaging optimization 441–2, 444–5 TTIs and monitoring during distribution 112–16 Shelf Life Decision System (SLDS) 120–1 Shewanella putrefaciens 386 Shigella sonnei 240 species 239 shock 537–8 shredded lettuce 568–72 silica gel 173–4, 175 silicates 172, 176–8 silver nitrate 56 silver zeolite 56, 391 simulants 474, 476–7 size 490 slaughtering facilities 378 Smellrite/Abscents 44 sniffing device 513 see also electronic nose snorkel type (ST) machines 198, 374–5, 377 sodium chloride (salt) 172, 178, 292, 297–8 sodium lactate (Na-lactate) 292, 299 softdrink bottles 511, 512 solubility 62–3 soluble gas stabilisation (SGS) 292, 300, 387–8, 388–90 solvent casting 63 sorbic acid 297 source control 499, 500 spacers, polymeric 88 specific activity 60 specific migration limit (SML) 460, 529 specific spoilage organisms (SSOs) 386 spoilage 588 Index fish 385–7, 395–6 MAP, food preservation and 312–14 meat 369–72 delaying microbial spoilage 369–71 mechanisms 314 micro-level modelling 345 see also microorganisms spore-forming bacteria 293–4 stability 72–4 standards, suitability with respect to 446, 448–9, 449–58 Staphylococcus aureus 324–5, 326, 328, 332, 333, 334 starch 522 native 522 thermoplastic 522, 526, 527, 530 starch-based polymers 520, 522–4, 530, 531 starch-clay nano-composites 524–6, 527 Stefan-Maxwell equations 348 stock rotation 116–21 storage 63, 445 integrating active packaging, distribution and 5, 18, 204, 535–49 meat colour stability 402–3, 404–8 effects of temperature 371–2 reducing pathogen risks 254 strain variation 251 Strecker degradation reaction 41 stress responses 250–1, 255–6 STRIPPAX sachet 44, 394 succinimidyl succinate (SS) esters 89–90 sulphur dioxide emitters 9 sulphuric compounds 131–2 super-chilling 294–5, 396 super-clean processes 503–4 cleaning efficiency 506–7 supermarkets 377–8 supply chain 535–49 intelligent supply chain 18 for perishable foods 535–8 role of packaging in 5–6, 538–40 see also integrated active packaging, storage and distribution surface functionalisation 79, 85–8 surface-treated packaging materials 10 sweeteners 480–1 swelling, polymer 86 symbols ’do not eat’ 489–90 for food contact materials 471 synthetic polyesters 523, 530 tagging 18 Temchron indicator 108 temperature 181, 313, 537–8 control and high oxygen MAP 201 glass transition temperature 146, 147 low temperature preservation 292, 294–5, 396 MAP performance under dynamic temperature conditions 563–75 meat colour stability 404–8 effects on storage life 371–2 packaging-flavour interaction 149, 158 reducing pathogen risks 254, 256 storage temperature and pathogen survival 242–3 surface temperature after irradiation 335 temperature-sensitive films 10 Tempil indicator 108 tenderisation 369 texture 368–9 thermoform-fill-seal (TFFS) machines 192, 326–7 thermoplastic starch (TPS) 522, 526, 527, 530 three-layered PP cups 510–11 3M Monitor Mark 108, 108–9 time 537–8 time-temperature indicators (or integrators) (TTIs) 11, 94–5, 103–26 consumer acceptance 557–9 current TTI systems 108–10 defining and classifying 104–6 development of 106–8 fish 394, 396 future trends 121–2 integrated packaging, storage and distribution 540–1 legislation and 473–4, 486 MAP performance 565 maximising effectiveness of 111 monitoring shelf-life during distribution 112–16 optimization of distribution and stock rotation 116–21 requirements for 106 total immersion 476–7 toxicity 490 toxicological evaluation 466–7 Toxin Alert indicator 395 Toxin Guard 136 traceability 18, 542–5, 546 tracer gas leak detection 279 Index 589 traditional preservation methods 51 transportation 483, 536–7, 537–8 trimethylamine (TMA) 130, 386 trimethylamine-oxide (TMAO) 385–6 tristimulus colorimetric measurements 418–19 2–in-1 44, 394 tyramine 130–1 ultraviolet (UV) radiation 255, 314–15, 315–20 combined UV/ozone lamp 317–18, 327–32, 335–6 future trends 332–6 UV irradiated nylon 10, 82–3 UV-light absorbers 8 UNIFAC group contribution model 160 ‘unintended’ atmospheres 247–8 United States (USA) 12, 14, 75–6 FDA 504, 514–15 ‘use by’ date 485, 486, 487 vacuum chamber (VC) machines 192 vacuum packaging 12, 22–3 variation 345–6, 350–1, 356, 572–3 Verifrais package 390 vertical form-fill-seal (VFFS) machines 198, 326 vibration 537–8 viruses 239–42, 243, 247, 320 visual oxygen indicators 280, 281–2 vitamin C 216–18 vitamin E 44 VITSAB TTIs 109, 110, 394 volatile nitrogen compounds 130, 135 volume control 488–9, 573 volume ratio 198–9, 409–10 VTT Precision Packaging Concept 441–58 basic requirements 444–5 calculating the coefficients 448–9 examples of use 449–58 importance of package characteristics 448 improving decision-making 458 optimization results 449 package and storage combinations 445 scoring selected package types 445–8 warm product, packing 508, 568, 569–72, 573 washing fresh produce 245–7 recycling technology 503–4, 505–6 see also super-clean processes waste legislation 491–2 problem of plastic packaging waste 519–20 volume of package waste 446, 448–9, 449–58 water modelling diffusion and loss 344, 349 packaging-flavour interaction 149, 154–5 resistance of starch-based products 522–3 see also humidity; moisture regulation water activity 182 water of hydration 179 weight control 488–9 wet chemical oxidation procedures 86–7 Wexler’s equation 178 white light 332–3, 334 wholesale 491 wine barrels 482 xenon flashlamp 332–3, 334 yeasts 231, 320 Yersinia enterocolitica 212–14, 238, 241, 246, 290 species 235 Zero 2 oxygen scavenger 32 590 Index