21 High pressure processing Indrawati, A. Van Loey and M. Hendrickx, Katholieke Universiteit, Leuven 21.1 Introduction Food quality, including colour, texture, flavour and nutritional value, is of key importance in the context of food preservation and processing. Colour, texture and flavour refer to consumption quality, purchase and product acceptability whereas the nutritive values (i.e. vitamin content, nutrients, minerals, health- related food components) refer to hidden quality aspects. In conventional thermal processing, process optimisation consists of reducing the severity of the thermal process in terms of food quality destruction without compromising food safety. Due to the consumer demand for fresher, healthier and more natural food prod- ucts, high pressure technology is considered as a new and alternative unit opera- tion in food processing and preservation. 21.2 High pressure processing in relation to food quality and safety The effect of high pressure on food microorganisms was reported for the first time by Hite in 1899, by subjecting milk to a pressure of 650 MPa and obtaining a reduction in the viable number of microbes. Some years later, the effect of high pressure on the physical properties of food was reported, e.g. egg albumin co- agulation (Bridgman, 1914), solid–liquid phase diagram of water (Bridgman, 1912) and thermophysical properties of liquids under pressure (Bridgman, 1923). A more extensive exploration of high pressure as a new tool in food technology started in the late 1980s (Hayashi, 1989). Recently, extensive research has been conducted and is in progress on possible applications of high pressure for food preservation purposes or for changing the physical and functional properties of foods. The potentials and limit- ations of high pressure processing in food applications have become more clear. A number of key effects of high pressure on food components have been de- monstrated including (i) microorganism inactivation; (ii) modification of bio- polymers including enzyme activation and inactivation, protein denaturation and gel formation; (iii) quality retention (e.g. colour, flavour, nutrition value) and (iv) modification of physicochemical properties of water (Cheftel, 1991; Knorr, 1993). One of the unique characteristics of high pressure is that it directly affects non-covalent bonds (such as hydrogen, ionic, van der Waals and hydrophobic bonds) and very often leaves covalent bonds intact (Hayashi, 1989). As a conse- quence, it offers the possibility of retaining food quality attributes such as vita- mins (Van den Broeck et al, 1998), pigments (Van Loey et al, 1998) and flavour components, while inactivating microorganisms and food-quality related enzymes, changing the structure of food system and functionality of food pro- teins (Hoover et al, 1989; Knorr, 1995; Barbosa-Cànovas et al, 1997; Messens et al, 1997; Hendrickx et al, 1998). Furthermore, by taking advantage of the effect on the solid liquid phase transition of water, some potential applications in food processing such as pressure-assisted freezing (pressure shift freezing), pressure- assisted thawing (pressure shift thawing), non-frozen storage under pressure at subzero temperature and formation of different ice polymorphs can be offered while keeping other food quality properties (Kalichevsky et al, 1995). Besides, pressure can also induce increased biochemical reaction rates with effect on bio- conversions and metabolite production (Tauscher, 1995). Based on these effects of high pressure on food systems, several potential applications can be identified such as high pressure pasteurisation of fruit and vegetables products (Parish, 1994; Yen and Lin, 1996), tenderisation of meat products (Elgasim and Kennick, 1980; Ohmori et al, 1991; Cheftel and Culioli, 1997), texturisation of fish pro- teins, applications in the dairy industry (Messens et al, 1997) and high pressure freezing/thawing (Kalichevsky et al, 1995). With regard to food safety, the effect of combined high pressure and tem- perature on microorganisms has been investigated extensively (Sonoike et al, 1992; Hashizume et al, 1995; Knorr, 1995; Heinz and Knorr, 1996; Hauben, 1998; Reyns et al, 2000). The number of vegetative cells can be remarkably reduced by applying pressures up to 400 MPa combined with moderate temperatures up to 40°C for 10–30 minutes (Knorr, 1995). On the other hand, exposing the sur- viving fraction of vegetative cells to repeated pressure cycles can also increase their pressure resistance, e.g. Escherichia coli mutants resistant to high pressure inactivation were created (Hauben, 1998; Alpas et al, 1999; Benito et al, 1999). Microbial spores can be inactivated by exposure to high pressure but a pressure treatment at room temperature may not be sufficient for substantial reduction of viable spore counts. Most studies show that pressure can induce spore germina- tion and the extent of spore inactivation can be increased by increasing pressure and temperature (Knorr, 1995; Wuytack, 1999). However, tailing phenomena for germination and inactivation curves can occur for ‘super dormant’ spores after 434 The nutrition handbook for food processors long exposure times. As a consequence, to achieve sterility with minimal impact on nutrition value, flavour, texture and colour, high pressure processing using multiple high pressure pulses and achieving an end temperature above 105°C under pressure for a short time has been proposed (Meyer et al, 2000; Krebbers et al, 2001). 21.3 High pressure technology and equipment for the food industry High pressure technology has been used in the industrial production process of ceramics, metals and composites in the last three decennia. As a result, today, high pressure equipment is available for a broad range of process con- ditions, i.e. pressures up to 1000 MPa, temperatures up to 2200°C, volumes up to several cubic meters and cycling times between a few seconds and several weeks. Since high pressure technology offers advantages in retaining food quality attributes, it has recently been the subject of considerable interest in the food industry as a non-thermal unit operation. High pressure equipment with pressure levels up to 800 MPa and temperatures in the range of 5 to 90°C (on average) for times up to 30 minutes or longer is currently available to the food industry. The actual high pressure treatment is a batch process. In practice, high pres- sure technology subjects liquid or solid foods, with or without packaging, to pres- sures between 50 and 1000 MPa. According to Pascal’s principle, high pressure acts instantaneously and uniformly throughout a mass of food and is independent of the size and shape of food products. During compression, a temperature increase or adiabatic heating occurs and its extent is influenced by the rate of pressurisation, the food composition and the (thermo)physical properties of the pressure transfer medium. The temperature in the vessel tends to equilibrate towards the surrounding temperature during the holding period. During pressure release (decompression), a temperature decrease or adiabatic cooling takes place. In high pressure processing, heat cannot be transferred as instantaneously and uniformly as pressure so that temperature distribution in the vessel might become crucial. During the high pressure treatment, other process parameters such as treatment time, pressurisation/decompression rate and the number of pulses have to be considered as critical. Two types of high pressure equipment can be used in food processing: con- ventional batch systems and semi-continuous systems. In the conventional batch systems, both liquid and solid pre-packed foods can be processed whereas only pumpable food products such as fruit juice can be treated in semi-continuous systems. Typical equipment for batch high pressure processing consists of a cylin- drical steel vessel of high tensile strength, two end closures, a means for restrain- ing the end closures (e.g. a closing yoke to cope with high axial forces, threads, pins), (direct or indirect) compression pumps and necessary pressure controls and High pressure processing 435 instrumentation. Different types of high pressure vessels can be distinguished, i.e. (i) ‘monobloc vessel’ (a forged constructed in one piece); (ii) ‘multi layer vessel’ consisting of multiple layers where the inner layers are pre-stressed to reach higher pressure or (iii) ‘wire-wound vessel’ consisting of pre-stressed vessels formed by winding a rectangular spring steel wire around the vessel. The use of monobloc vessels is limited to working pressures up to 600 MPa and for high pressure application above 600 MPa, pre-stressed vessels are used. The position of high pressure vessels can be vertical, horizontal or tilting depending on the way of processing (Mertens and Deplace, 1993; Zimmerman and Bergman, 1993; Galazka and Ledward, 1995; Mertens, 1995; Knorr, 2001). 21.4 Commercial high pressure treated food products With regard to the large-scale application of high pressure technology in the food industry, a problem still to be solved today is the improvement of the economic feasibility, i.e. the high investment cost mainly associated with the high capital cost for a commercial high pressure system. The cost of a vessel is determined by the required working pressure/temperature and volume. Furthermore, once technically and economically feasible processes have been identified, one needs to evaluate whether the unique properties of the food justify the additional cost and to what extent consumers are willing to pay a higher price for a premium quality product. High pressure technology is unlikely to replace conventional thermal pro- cessing, because the second technique is a well-established and relatively cheap food preservation method. Currently, the reported cost range of high pressure processes is 0.1–0.2 $ per litre (Grant et al, 2000) whereas the cost for thermal treatment may be as low as 0.02–0.04 $ per litre. However, the technology offers commercially feasible alternatives for conventional heating in the case of novel food products with improved functional properties which cannot be attained by conventional heating. Today, several commercial high pressure food products are available in Japan, Europe and the United States. A Japanese company, Meidi-Ya, introduced the first commercial pressure treated product (a fruit-based jam) on the market in April 1990, followed in 1991 by a wide variety of pressure-processed fruit yoghurts, fruit jellies, fruit sauces, savoury rice products, dessert and salad dress- ings (Mertens and Deplace, 1993). Recently, there were more than 10 pressure treated food products available in Japan. In Europe, fruit juice was the first commercially available high pressure product in France followed by a pressurised delicatessen style ham in Spain and pressurised orange juice in the United Kingdom. In the United States, high pressure treated guacamole has been launched on the commercial market. In addition, pressure treated oysters and hummus are commercially available. A list of commercially available pressurised food products in Japan, Europe and the United States in the last decade is sum- marised in Table 21.1. 436 The nutrition handbook for food processors 21.5 Effect of high pressure on vitamins Many authors have reported that the vitamin content of fruit and vegetable prod- ucts is not significantly affected by high pressure processing. According to Bignon (1996), a high pressure treatment can maintain vitamins C, A, B 1 , B 2 , E and folic acid and the decrease of vitamin C in pressurised orange juice is neg- ligible as compared to flash pasteurised juices during storage at 4°C for 40 days. Similar findings have been reported for red orange juice; high pressure (200– 500 MPa/30°C/1 min) did not affect the content of several vitamins (vitamins C, B 1 , B 2 , B 6 and niacin) (Donsì et al, 1996). 21.5.1 Ascorbic acid The effect of high pressure treatment on ascorbic acid has been more intensively studied than on vitamins such as A, B, D, E and K. Studies on ascorbic acid stability in various food products after high pressure treatment are available. Most authors have reported that the ascorbic acid content is not significantly affected by high pressure treatment. For example, in fruit and vegetables, about 82% of the ascorbic acid content in fresh green peas can be retained after pres- sure treatment at 900 MPa/20°C for 5–10 minutes (Quaglia et al, 1996). Almost 95–99% of the vitamin C content in strawberry and kiwi jam can be preserved by pressurisation between 400 and 600 MPa for 10–30 min (Kimura, 1992; Kimura et al, 1994). In freshly squeezed citrus juices, high pressures up to 600 MPa at 23°C for 10 min did not affect the initial (total and dehydro) ascor- bic acid concentration (Ogawa et al, 1992). Similar findings are also reported in strawberry ‘coulis’ (a common sauce in French dessert) and strawberry nectar; the vitamin C content was preserved after 400 MPa/20°C/30 min (88.68% of the initial content in fresh sample) and in guava purée, high pressure (400 and 600 MPa/15 min) maintained the initial concentration of ascorbic acid (Yen and Lin, 1996). Also, ascorbic acid stability in egg yolk has been investigated, showing that high pressure treatment (200, 400, 600 MPa) at 20°C for 30 min did not significantly affect the vitamin C content (Sancho et al, 1999). The evolution of the vitamin C content in high pressure treated food products during storage has also been investigated. Most studies show that storage at low temperature can eliminate the vitamin C degradation after high pressure treat- ment. For example, the quality of high pressure treated jam was unchanged for 2–3 months at 5°C but a deterioration of vitamin C was noticed during storage at 25°C (Kimura, 1992; Kimura et al, 1994). Another study on strawberry nectar showed that ascorbic acid remained practically the same during high pressure processing (500 MPa/room temperature/3 min) but decreased during storage (up to 75% of the initial concentration after storage for 60 days at 3°C) (Rovere et al, 1996). In valencia orange juice, the percentage of ascorbic acid in pressurised juice (500–700 MPa/50–60°C/60–90 s) was 20–45% higher than in heat treated juice (98°C/10 s) during storage at 4 and 8°C for 20 weeks (Parish, 1997). Studies on guava purée showed that different high pressure processes have a High pressure processing 437 438 The nutrition handbook for food processors Table 21.1 Commercial pressurised food products in Japan, Europe and the United States in the last ten years (after Cheftel, 1997) Company Product P/T/time combination Role of HP JAPAN Meidi-ya Fruit based products (pH < 4.5); jams 400 MPa, 10–30 min, Pasteurisation, improved gelation, faster sugar (apple, kiwi, strawberry); jellies; 20 °C penetration; limiting residual purées; yoghurts; sauces pectinmethylesterase activity Pokka Corp. (stopped Grapefruit juice 200 MPa, 10–15 min, Reduced bitterness c2000–2001) 5°C Wakayama Food Ind. Mandarin juice (winter season only) 300–400 MPa, 2–3 min, Reduced odor of dimethyl sulphide; reduced (only H1101520% of HP juice in final juice 20 °C thermal degradation of methyl methionine mix) sulphoxide; replace first thermal pasteurisation (after juice extraction) and final pasteurisation before packing: 90 °C, 3 min Nisshin fine foods Sugar impregnated tropical fruits (kept 50–200 MPa Faster sugar penetration and water removal at -18 °C without freezing). For sorbet and ice cream Fuji chiku mutterham Raw pork ham 250 MPa, 3 hours, Faster maturation (reduced from 2 weeks to 20 °C 3 hours); faster tenderisation by internal proteases, improved water retention and shelf life Kibun (stopped in ‘Shiokara’ and raw scallops / Microbial sanitation, tenderisation, control of 1995) autolysis by endogenous proteases Yaizu fisheries (test Fish sausages, terrines and ‘pudding’ 400 MPa Gelation, microbial sanitation, good texture of market only) raw HP gel Chiyonosono ‘Raw’ sake (rice wine) / Yeast inactivation, fermentation stopped without heating High pressure processing 439 QP corp Ice nucleating bacteria (for fruit juice / Inactivation of Xanthomonas, no loss of ice and milk) nucleating properties Ehime co. Japanese mandarin juice / Cold pasteurisation Echigo seika Moci rice cake, Yomogi fresh aromatic 400–600 MPa, 10 min, Microbial reduction, fresh flavour and taste, herbs, hypoallergenic precooked rice, 45 or 70°C enhances rice porosity and salt extraction of convenience packs of boiled rice allergenic proteins Takansi Fruit juice / Cold pasteurisation Pon (test market in Orange juice / / 2000) EUROPE Pampryl (France) Fruit juice (orange, grape fruit, citrus, 400 MPa, room Inactivation of micro flora (up to 10 6 CFU/g), mixed fruit juice) temperature partial inactivation of pectinmethylesterase Espuna (Spain) Deli-style processed meats (ham) 400–500 MPa, few / minutes, room temperature Orchard House Foods Squeezed orange juice 500 MPa, room Inactivation of micro flora (especially yeast) Ltd. (UK) (since July temperature and enzyme, keeping natural taste 2001) THE UNITED STATES Avomex Avocado paste (guacamole, chipotle 700 MPa, 10–15 min, Microorganism inactivation, polyphenoloxidase sauce, salsa) and pieces 20°C inactivation, chilled process Motivatit, Nisbet Oysters 300–400 MPa, room Microorganism inactivation, keeping raw taste Oyster Co, Joey Oyster temperature, 10 minutes and flavour, no change in shape and size Hannah International Hummus / / Foods / indicates no detailed information available. Table 21.1 Commercial pressurised food products in Japan, Europe and the United States in the last ten years (after Cheftel, 1997) Company Product P/T/time combination Role of HP Continued different influence on the stability of vitamin C during storage. The ascorbic acid content in untreated and pressurised (400 MPa/room temperature/15 min) guava puree started to decline respectively after 10 and 20 days whereas that in heated (88–90°C/24 s) and (600 MPa/room temperature/15 min) pressurised guava purée remained constant during 30 and 40 days respectively (Yen and Lin, 1996). Kinetics of vitamin C degradation during storage have been studied in high pressure treated strawberry coulis. Vitamin C degradation of pressurised (400 MPa/20°C/30 min) and untreated coulis are nearly identical during storage at 4°C. Moreover, it has been shown that a pressure treatment neither accelerates nor slows down the kinetic degradation of ascorbic acid during subsequent storage (Sancho et al, 1999). The effect of oxygen on ascorbic acid stability under pressure has been studied by Taoukis and co-workers (1998). At 600 MPa and 75°C for 40 min exposed to air, ascorbic acid in buffer solution (sodium acetate buffer (0.1 M; pH 3.5–4)) degraded to 45% of its initial content while in the absence of oxygen, less vitamin loss was observed. Moreover, the addition of 10% sucrose resulted in a protec- tive effect on ascorbic acid degradation. It was also noted that vitamin C loss was higher in fruit juice compared to that in buffer solutions. Vitamin C loss in pine- apple and grapefruit juice after pressurisation (up to 600 MPa and 75°C) was max. 70% and 50% respectively. At constant pressure (600 MPa after 40 min), the pres- sure degradation of vitamin C in pineapple juice was temperature sensitive, e.g. loss 20–25% at 40°C, 45–50% at 60°C and 60–70% at 75°C in contrast to that in grapefruit juice. Detailed kinetics of combined pressure and temperature stability of ascorbic acid in different buffer (pH 4, 7 and 8) systems and real products (squeezed orange and tomato juices) have been carried out by Van den Broeck and co- workers (1998). At 850 MPa and 50°C for 1 hour, no ascorbic acid loss was observed. The high pressure/thermal degradation of ascorbic acid at 850 MPa and 65–80°C followed a first order reaction. The rate of ascorbic acid degradation at 850 MPa increased with increasing temperature from 65 to 80°C indicating that pressure and temperature act synergistically. Ascorbic acid in tomato juice was more stable than in orange juice. It was also reported that temperature depend- ence of ascorbic acid degradation (z value) was independent of the pressure level. Based on this study, it can be concluded that ascorbic acid is unstable at high pressure (850 MPa) in combination with high temperature (65–80°C). 21.5.2 Vitamin A and carotene The effect of high pressure treatment on carotene stability has been studied in carrots and in mixed juices. Based on the available literature data, we can con- clude that high pressure treatment does not affect (or affects only slightly) the carotene content in food products. a- and b-carotene contents in carrot puree were only slightly affected by pressure exposure at 600 MPa and 75°C for 40 min (Tauscher, 1998). Similar findings have also been reported by de Ancos and co- workers (2000) showing that carotene loss in carrot homogenates and carrot paste 440 The nutrition handbook for food processors was maximally 5% under pressure condition of 600 MPa/75°C/40 min. In orange, lemon and carrot mixed juice, high pressure (500 and 800 MPa/room tempera- ture/5 min) did not affect or only slightly affected the carotenoid content and during storage at 4°C; the carotenoid content in the pressure treated juice remained constant for 21 days (Fernández Garcia et al, 2001). In addition, high pressure treatment can affect the extraction yield of carotenoids. Studies on persimmon fruit purées showed that high pressure treat- ment could increase the extraction yield of carotenoids between 9 and 27% e.g. Rojo Brillante cultivars (50 and 300 MPa/25°C/15 min) and Sharon cultivars (50 and 400 MPa/25°C/15 min). The increase in extraction yield of carotene (40% higher) was also found in pressurised carrot homogenate (600 MPa/25°C/10 min) (de Ancos et al, 2000). Pressure stability of retinol and vitamin A has been studied in buffer systems. In the model systems studied, pressure treatment could induce degradation of vitamin A. For example, pressures up to 400–600 MPa significantly induced retinol (in 100% ethanol solution) degradation. Degradation up to 45% was obtained after 5 minutes exposure to 600 MPa combined with temperatures at 40, 60 and 75°C. Pressure and temperature degradation of retinol followed a second order reaction. Another study on vitamin A acetate (in 100% ethanol solution) showed that degradation of vitamin A acetate was more pronounced by increas- ing pressure and temperature. About half of the vitamin A acetate concentration could be retained by pressure treatment at different pressure/temperature/time combinations, i.e. 650 MPa/70°C/15 minutes and 600 MPa/25°C/40 minutes. At 90°C, complete degradation was observed after 2–16 minutes (pressure up to 600 MPa). No effect of oxygen was noticed on retinol and vitamin A acetate degradation (Butz and Tauscher, 1997; Kübel et al, 1997; Tauscher, 1999). However, findings on retinol pressure stability in real food products differ from those obtained in model systems. In egg white and egg yolk, the initial retinol content can be preserved by pressure treatment from 400 up to 1000 MPa at 25°C for 30 minutes (Hayashi et al, 1989). 21.5.3 Vitamins B, E and K The stability of vitamins B, E and K towards pressure treatment has been studied in model systems and food products. In food model systems, high pressure (200, 400, 600 MPa) treatments at 20°C for 30 minutes have no significant effect on vitamin B 1 (thiamine) and B 6 (pyridoxal) (Sancho et al, 1999). Studies on the pressure effect on vitamin K 1 showed that small quantities of m- and p-isomeric Diels–Alder products were formed after 3 hours at 650 MPa and 70°C (Tauscher, 1999). In cow’s milk, high pressure (400 MPa/room temperature/30 minutes) did not alter the content of vitamin B 1 and B 6 (pyridoxamine and pyridoxal) (Sierra et al, 2000). The thiamine content in pork meat was not affected by high pressure (100–250 MPa/20°C/10 minutes) even after long exposure time of 18 h at 600 MPa and 20°C (Bognar et al, 1993). However, under extreme conditions of High pressure processing 441 high temperature (100°C) combined with 600 MPa, almost 50% of the thiamine in pork meat was degraded within 15 min. Moreover, riboflavin in pork meat was only slightly affected (less than 20%) after pressure treatment at 600 MPa for 15 minutes combined with temperatures between 25 and 100°C (Tauscher, 1998). Heat-sensitive vitamin derivatives in egg white and/or egg yolk, i.e. riboflavin, folic acid, a-tocopherol and thiamine did not change during pressure treatment from 400 up to 1000 MPa at 25°C for 30 minutes (Hayashi et al, 1989). It can be concluded that high pressure treatment has little effect on the vitamin content of food products. However, at extreme conditions of high pressure com- bined with high temperature for a long treatment time period, vitamin degrada- tion is observed. Regarding the use of high pressure in industrial applications, an optimised pressure/temperature/time combination must be chosen to obtain limited vitamin destruction within the constraints of the target microbial inacti- vation. For example, a mild pressure and temperature treatment can be developed equivalent to the conventional pasteurisation processes in order to keep the vitamin content in food products while inactivating vegetative microbial cells. When spore inactivation is targeted, combined high pressure thermal treatments are needed and these treatments will affect nutrients. It is still an open question whether equivalent conventional thermal and new high pressure processes used for spore inactivation lead to improved vitamin retention. The available data suggest positive effects but more research is needed. 21.6 Effect of high pressure on lipids The most interesting effect of high pressure on lipids in foods is the influence on the solid–liquid phase transition, e.g. a reversible shift of 16°C per 100 MPa for milk fat, coconut fat and lard (Buchheim et al, 1999). With respect to the nutri- tional value of lipids, the effect of high pressure on lipid oxidation and hydroly- sis in food products is of importance. Lipid oxidation is a major cause of food quality deterioration, impairing both flavour and nutritional values (related to health risks, e.g. development of both coronary heart disease and cancer). Effect of high pressure on lipids has been reported by many authors and the available literature shows that pressure could induce lipid oxidation especially in fish and meat products but did not, or only slightly, affect lipid hydrolysis. For example, pressures up to 1000 MPa and 80°C did not affect the hydrolysis of tripalmitin and lecithin. Therefore, no fat/oil hydrolysis is expected to occur under condi- tions relevant for food processing (e.g. 600 MPa/60°C/time less than 30 minutes) (Isaacs and Thornton-Allen, 1998). Pressure induced lipid oxidation has been studied in different model systems and food products. In model systems, pressures up to 600 MPa and temperatures up to 40°C (less than 1 hour) had no effect on the main unsaturated fatty acid in milk, i.e. oleic acid. Linoleic acid oxidation was accelerated by exposure to pres- sure treatments of less than one hour, but the effect was relatively small (about 10% oxidation) (Butz et al, 1999). Increasing pressure (100 up to 600 MPa and 442 The nutrition handbook for food processors 40°C) lowered the decrease of alpha-linoleic acid indicating that pressure retarded lipid oxidation e.g. 15% decrease at 600 MPa/40°C/15 minutes and 30% decrease at 100 MPa/40°C/15 minutes. As a consequence, pressures above 600 MPa are suggested for retention of essential fatty acids, e.g. linoleic acids (Kowalski et al, 1996). 21.6.1 Vegetable oils Pressure induced lipid oxidation of extra virgin olive and seed oil has been studied by Severini and co-workers (1997). The peroxide values, indicating the primary oxidation products, of untreated and pressure treated (700 MPa/room tempera- ture/10 minutes) olive oil were not significantly different. In seed oil i.e. sun- flower and grape-stone oil, this value was evidently increased due to pressure treatment and storage (-18°C, 1 year); such effects were not found for soybean, peanut and maize oil. The two former seed oils show the highest level of un- saturated fatty acids which probably affects lipid oxidation. The para-anisidine value, indicating secondary oxidation products such as aldehydes, generally increased after high pressure treatment (700 MPa/room temperature/10 minutes), e.g. olive oil (types A, B, C, D), sunflower, peanut and maize oil samples and after one year storage at -18°C, only the value in seed oil increased. The induc- tion time (i.e. length of the initial stage of very slow oxidation) of pressure treated olive oil was generally shorter than that needed for untreated samples. Such a phenomenon was also found in the seed oils i.e. grape-stone, sunflower and peanut oils. It can be concluded that the olive oil was more pressure resistant to oxidation than was seed oil and, as a consequence, extra virgin olive oil is a better choice in high pressure processed foods. The effect of high pressure on essential oils of spices and herbs has been reported. The essential oil content in basil can be retained by pulsed high pres- sure sterilisation (2 pulses of 1 minute holding time) using high pressure (≥700 MPa) combined with high temperature (≥65°C) processing while losses after conventional heat sterilisation were over 65%. It was stated that pulsed high pressure opens new perspectives in quality improvement of fresh spices and herbs (Krebbers et al, 2001). 21.6.2 Fish products In fish products, some studies show occurrences of pressure induced lipid oxi- dation. The lipid oxidation rate (based on TCA (thiobarbituric acid) number) in cod muscle remarkably increased by pressurisation above 400 MPa (study up to 800 MPa) at 20°C for 20 min. EDTA (ethylenediaminetetraacetic acid) addition (1% w/w) in minced cod muscle inhibited the increased oxidation rate induced by pressure treatment. It was suggested that release of transition metal ions such as copper or iron or their complexes occurred under pressure and subsequently catalysed the oxidation reaction. Lipid oxidation in cod muscle packed under air was limited at treatments of 200 MPa and room temperature for 20 minutes (Angsupanich and Ledward, 1998). High pressure processing 443 Production of free fatty acids in red fish meat, i.e. sardine and bonito, during storage was inhibited after pressure treatment at 200 MPa and room temperature for 30 minutes. Pressures above 200 MPa resulted in lipid degradation. This observation was explained by the degradation of myoglobin and the loss of the water holding capacity increasing the contact surface layer between oxygen and fish meat. The oxidation pattern of pressurised (100 MPa/room temperature/30 minutes) sardine and bonito was almost the same for as long as 3 days of storage (5°C). Addition of antioxidants (a mixture of alpha tocopherol and rosemary) pro- longed the storage for 12 days for untreated samples but only for 6 and 9 days respectively for 100 and 200 MPa pressurised samples. It could be that high pres- sure also affects the radical scavenger function of alpha tocopherol and rosemary (Wada, 1992; Wada and Ogawa, 1996). 21.6.3 Meat products In meat products, the induction time of pressure treated (800 MPa/19°C/20 minutes) rendered pork fat (a w = 0.44) was shorter (approximately 3 days) than that of untreated samples (c 4 days). Pressure treated samples showed a higher peroxide value than untreated samples and the effect became more pronounced with increasing pressure. Furthermore, the extent of lipid oxidation at 800 MPa for 20 min was increased by increasing the treatment temperature. High pressure treatment inhibited lipid oxidation at all water activities except a w = 0.44. Since pork fat contains up to 1.5 ppm iron and 0.4 ppm copper, transition metals may be released from complexes and act as powerful pro-oxidants. In the a w range between 0.4 and 0.55, pressure becomes catalytic to the oxidation and the cata- lytic effect of the released metal ions probably overrides the inhibiting effect of peroxide destruction. At higher a w , free ions will hydrate with the available water, whereas at lower a w such hydration may not be complete and increases the cata- lytic effects of the ions. It seemed that pressure treatment at higher temperature diminished the inhibiting/protective effect on lipid oxidation and high pressure application for a short time had a significant effect on stability of pork lipids during subsequent storage indicating that high pressure leads to irreversible changes (Cheah and Ledward, 1995). Addition of citric acid (0.02%) prior to pres- sure (650–800 MPa) treatment of rendered pork fat inhibited the increased rate of lipid oxidation while it was less effective in minced pork and washed muscle because of the pH decrease. On the other hand, the addition of EDTA was effec- tive in inhibiting pressure induced oxidation. It indicated that releasing metal transition ions during pressure treatment was a major factor in increasing lipid oxidation in pressurised meat (Cheah and Ledward, 1997). Kinetics of lipid oxidation during pressure treatment have been reported by Dissing and co-workers (1997). In this investigation, turkey meat has been chosen as a case study since it is rather susceptible to oxidation due to its rela- tively large content of membrane-associated phospholipids in combination with a low endogenous level of tocopherol. Pressure treatment (100–500 MPa/ 10°C/10–30 min) induced lipid oxidation in turkey thigh muscles prior to chilled 444 The nutrition handbook for food processors storage. During storage, the increase of thiobarbituric acid reactive substances in pressurised (up to 400 MPa/10°C/10–30 min) meat was less pronounced than in heat (100°C/10 min) treated samples. The extent of lipid oxidation depends on the pressure level and treatment time. The enhancement of lipid oxidation was dependent on the pressure level applied, at least above a certain threshold pres- sure (i.e. 100 MPa). The evidence of pressure induced lipid oxidation may limit high pressure application in meat/fish based products unless antioxidants or suitable product packaging are used. Metal chelators which effectively remove the metal catalysts have been proposed as the most appropriate antioxidants to prevent lipid oxida- tion in meat products. 21.7 Effect of high pressure on other health-related food compounds 21.7.1 Sweeteners Synthetic dipeptide aspartame (aspartylphenylalanyl methyl ester) is widely used as a sweetener in light (low calorie) foods and diets for diabetics. The effect of high pressure on aspartame stability has been reported by Butz and co-workers (1997). Aspartame (0.5 g/L corresponding to the concentration in commercial diet cola and chocolate milk) in full cream milk (pH 6.8) lost almost 50% of active substances after pressure treatment at 600 MPa and 60°C for 3 minutes while the non-sweet compounds, i.e. aspartylphenylalanine and diketopiperazine, were formed. One of the important factors influencing the pressure stability of aspar- tame was the pH. It was stated that low pH foods containing aspartame could be treated by high pressure without great loss of active substances while high pres- sure treatment of dairy products (at neutral pH) such as chocolate milk and ice cream may create problems (possibly toxicological ones). After pressure treat- ment at 600 MPa and 60°C (pH 7), 1.15 mM of diketopiperazine (corresponding to 300 mg/L) could be present after 5 minutes. In this case, a human individual of 40 kg consuming 1 L of pressurised chocolate milk would ingest the upper limit of diketopiperazine (acceptable daily intake, ADI) of 7.5 mg/kg of body weight. As a consequence, it would be inadvisable to compensate the pressure related aspartame loss by adding higher aspartame doses prior to pressure treatment because it results in even higher diketopiperazine concentrations in the end-product. 21.7.2 Mineral content Information on the effect of high pressure on the mineral content of food prod- ucts is very scarce. Pressure treatment (600 MPa/room temperature/20 minutes) could increase up to 50% the soluble iron content of liver suggesting the break up of the protein coat surrounding the cluster of hydrous ferric oxide in ferritin. The soluble iron content in spinach and soya flour was unaffected by pressure High pressure processing 445 treatment. In beef muscle, the soluble iron was decreased by up to 50% and 67% respectively after pressure and heat treatments. Based on this study, the evidence of increasing rate of lipid oxidation in pressure treated meats (see section 21.6) could be supported by iron complexes released from ferritin or perhaps haemosidrin (Defaye and Ledward, 1999). 21.7.3 Human anti-mutagenic and anti-carcinogenic compounds Diets rich in fruit and vegetables are found to be associated with a low incidence of many types of human cancer. Unfortunately, most of the antimutagenic activ- ity in fruit and vegetables is reduced by heat treatment. The effect of high pres- sure treatment at different temperatures on the antimutagenic activity of fruit and vegetables has been studied in detail by Butz and co-workers (1998). In straw- berry and grapefruit, heat (100°C/10 min) and pressure (400–800 MPa/25–35°C/ 10 minutes) had no effect on the antimutagenic activity. Carrots, kohlrabi, leek, spinach and cauliflower were characterised by strong antimutagenic potencies that are sensitive to heat but not to pressure. Antimutagenic activity of tomatoes and beets was affected by pressure but extreme high pressure/temperature conditions were required (tomatoes: 600 MPa/50°C/10 min and 800 MPa/35°C/ 10 min; beets: 800 MPa/35°C/10 min). It can be concluded that high pressure pro- cessing of vegetable juices offers advantages compared with thermal processing regarding their antimutagenicity. In broccoli, isothiocyanates have been shown to have cancer protective prop- erties. Application of high pressure (600 MPa) combined with temperature (25, 40, 60 and 75°C) increased the degradation rate of both allyl and benzyl isoth- iocyanate up to 4 times compared with treatment under ambient pressure. In addi- tion, the isothiocyanate degradation impaired such qualities as colour, flavour and some physiological properties. Therefore, high pressure technology may have limited application potential for food products containing isothiocyanates (Grupe et al, 1997). 21.7.4 Digestibility In dairy and egg-based products, pressure induced conformational changes of albumin in relation to its technological and nutritional functionality were ex- amined by determining the susceptibility of the treated protein to trypsin. High pressure treatment (600–800 MPa/25°C/5–10 min) of ovalbumin solutions in the absence of salt (NaCl) and sucrose did not modify the susceptibility of the resid- ual soluble protein to trypsin. Pressure insolubilised ovalbumin was not digested by trypsin. Pressure treatment at neutral pH in the presence of NaCl or sucrose resulted in a pressure dependent increase of the susceptibility of ovalbumin to trypsin. The highest increase in proteolysis was observed for ovalbumin treated at 800 MPa and 25°C for 10 min in the presence of 10% sucrose (Iametti et al, 1998). Similar phenomena have been reported for purified egg albumin. The pres- ence of sucrose in pressurised albumin (400–600 MPa/25°C/5 min) increased the 446 The nutrition handbook for food processors susceptibility to proteolysis and the increase was more pronounced than in the presence of NaCl (Iametti et al, 1999). Digestibility of pressurised foodstuffs has been studied in vitro (using digestibility tests) and in vivo (feeding trial in young pigs). Feeding trials (using a mixture of potatoes, carrots, meat, peas and vegetable oil) showed no changes in the digestibility of the individual nutrient fractions of pressurised foodstuffs as compared to fresh (untreated) ones. High pressure (500 MPa/20°C/10 min) did not affect the digestibility of the nitrogen free extract content, fats and crude extract fibre. The nitrogen retention in animals was only 45.4% of the nitrogen consumed when the heat treated feed was given while it was 58.6% using pres- surised food and 57.9% using an untreated feed. In vitro studies showed no significant differences between the high pressure treated, heat treated (100 °C) and untreated pork samples on digestibility. Pressure treated soybean had a better digestibility than the untreated sample and the lowest digestibility was found in heat treated samples (100°C) (Sch?berl et al, 1999). For meat and lupin protein, the effect of high pressure on protein digestibility has been studied using in vitro tests. Protein digestibility of pressurised meat was higher than that of heat treated meat. The effectiveness of food processing on protein digestibility in meat could be ranged in the following order: untreated > pressure treated (500 MPa/10°C/10 min) (70% of digestibility) ≥ pressure treated (200 MPa/10°C/10 min) (67% of digestibility) > heat treated (95°C/30 min) samples (43% of digestibility). For lupin proteins, the pressure induced digestibil- ity was more remarkable than for meat proteins and the ranking was different, i.e. pressure treated (500 MPa/10°C/10 min): digestibility up to 430% > heat treated (95°C/30 min): digestibility up to 300% > pressure treated (200 MPa/ 10°C/10 min): digestibility up to 140% ≥ untreated samples (de Lamballerie- Anton et al, 2001). 21.7.5 Allergens Most foods contain both major and minor allergens. The majority of food- allergic individuals are sensitive to one or more of the major allergens present in common allergic foods. The effect of different food processing unit operations on the immunochemical stability of celery allergens has been studied in detail using in vitro and in vivo tests by Jankiewicz and co-workers (1997). High anti- genic and allergenic activity in native celery was reduced by heat treatment and only mildly reduced by non-thermal processing such as high pressure (600 MPa/ 20°C), high voltage pulse treatment and irradiation. In dairy and egg based products, modification of epitopic regions of ovalbu- min in pressure-treated ovalbumin has been studied by Iametti and co-workers (1998 and 1999). Pressure treatment (600–800 MPa/25°C/5 min) resulted in modifications of the epitopic regions of the protein (determined by direct and non-competitive ELISA). Increasing the pressure level caused an increased loss of recognisability. Under pressure, ovalbumin in the presence of sucrose pre- sented a lower recognisability than in the presence of NaCl. Samples treated at High pressure processing 447 600–800 MPa/25°C/5 min in the presence of NaCl showed an affinity towards antibodies that was 40% lower than that of untreated protein. When comparing with the result determined by direct competitive ELISA, it can be concluded that pressure treatment did modify epitopic regions of ovalbumin. In the presence of sucrose, increasing protein concentrations led to a decrease in the specific content of antibody recognition sites per unit mass protein while no effect was found in the presence of NaCl. 21.8 Future trends in high pressure research Most review articles have pointed out the potential of high pressure as a non- thermal alternative for food processing and preservation allowing high retentions of food quality such as colour, flavour and nutrient value. The available infor- mation in literature is qualitative and fragmentary. Systematic quantitative data are very limited. The latter information is indispensable when providing satis- factory evidence for legislative bodies to enable the authorisation of high pres- sure technology in the food processing/preservation industries (e.g. EU legislation regarding ‘novel food’). Therefore, quantitative studies must be carried out in order to allow the assessment of the impact of high pressure processing on food quality and safety. In comparison with conventional thermal processing, high pressure as a novel unit operation should be able to guarantee increased overall quality, i.e. to increase functional properties within the constraints of microbial and toxicologi- cal safety. The occurrence of toxic or allergenic compounds in pressure treated food products must receive more attention in the future. The present situation requires further investigations and calls for more systematic studies. Today, high pressure treatments combined with high temperatures for short times have been proposed for food sterilisation because of their effective microbial spore inacti- vation. On the other hand, some articles have reported that the stability of nutri- ents (e.g. vitamins, lipids, health-related food compounds) and possibly chemical compounds is limited under such extreme pressure-temperature conditions. This calls for more research on these compounds under high pressure sterilisation con- ditions and both mechanistic and kinetic information are required. 21.9 Sources of further information and advice High pressure research has been concentrated in Japan, Europe and the United States. Lists of academic and non-academic research centres actively involved in high pressure research in the field of bioscience, food science and chemistry are tentatively summarised in Appendices 21.1 and 21.2; they are based on their par- ticipation in European and/or Japanese High Pressure Research conferences and Annual IFT meetings in the period 1991–2001. Further information on annual meetings of high pressure research in Japan, Europe and the United States can 448 The nutrition handbook for food processors be obtained from professional organisations such as the European High Pressure Research Group (http://www.kuleuven.ac.be/ehprg), the Institute of Food Tech- nologists (IFT) Non Thermal Division (http://www.ift.org/divisions/nonthermal/), the UK High pressure club for food processing (http://www.highpressure.org.uk) and the Japanese Research Group of High Pressure. Information about general aspects of high pressure processing can be found at the Ohio State University website (http://grad.fst.ohio-state.edu/hpp/) and FLOW website (http://www. fresherunderpressure.com/). 21.10 Acknowledgements The authors would like to thank the Fund for Scientific Research – Flanders (FWO) for their financial support. 21.11 References alpas h, kalchayanand n, bozoglu f, sikes a, dunne p and ray b (1999), ‘Variation in resistance to hydrostatic pressure among strains of food-borne pathogens’, Appl Environ Microbiol, 65(9), 4248–51 angsupanich k and ledward d a (1998), ‘Effects of high pressure on lipid oxidation in fish’, in Isaacs N S (ed), High Pressure Food Science, Bioscience and Chemistry, Cambridge, UK, The Royal Society of Chemistry, 284–7 barbosa-cánovas g v, pothakamury u r, palou e and swanson b g (1997), ‘High pressure food processing’, in Barbosa-Cánovas G V, Pothakamury U R, Palou E and Swanson B G (eds), Nonthermal Preservation of Foods, New York, 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Bioscience and Chemistry, Cambridge, UK, The Royal Society of Chemistry, 122–4 jankiewicz a, baltes w, b?gl k w, dehne l i, jamin a, hoffmann a, haustein d and vieths s (1997), ‘Influence of food processing on the immunochemical stability of celery allergens’, J Sci Food Agri, 75, 359–70 kalichevsky m t, knorr d and lillford p j (1995), ‘Potential food applications of high pressure effects on ice-water transitions’, Trends Food Sci Technol, 6, 253–9 kimura k (1992), ‘Development of a new fruit processing method by high hydrostatic pressure’, in Balny C, Hayashi R, Heremans K and Masson P, High Pressure and Biotechnology, Montrouge, John Libbey Eurotext Ltd, 224, 279–83 kimura k, ida m, yoshida y, ohki k, fukumoto t and sakui n (1994), ‘Comparison of keeping quality between pressure-processed and heat-processed jam: changes in flavour components, hue and nutritional elements during storage’, Biosci Biotechnol Biochem, 58, 1386–91 knorr d (1993), ‘Effects of high-hydrostatic-pressure 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(1997), ‘Influence of UHP on vitamin A’, in Heremans K (ed), High Pressure Research in the Biosciences and Biotechnology, Leuven, Belgium, Leuven University Press, 331–4 mertens b (1992), ‘Under pressure’, Food Manufacture, 11, 23–4 High pressure processing 451 mertens b and deplace g (1993), ‘Engineering aspects of high pressure technology in the food industry’, Food Technol, 47(6), 164–9 mertens b (1995), ‘Hydrostatic pressure treatment of food: equipment and processing’, in Gould G W (ed), New Methods of Food Preservation, Glasgow, Blackie Academic and Professional, 135–58 messens w, van camp j and huygebaert a (1997), ‘The use of high pressure to modify the functionality of food proteins’, Trends Food Sci Technol, 8, 107–12 meyer r s, cooper k l, knorr d and lelieveld h l m (2000), ‘High-pressure steriliza- tion of foods’, Food Technol, 54(11), 67–72 ogawa h, fukuhisa k and fukumoto h (1992), ‘Effect of Hydrostatic Pressure on Sterilization and Preservation of Citrus Juice’, in 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pressure-temperature inactivation of the yeast Zygosaccharomyces bailii’, Int J Food Microbiol, 56, 199–210 rovere p, carpi g, gola s, dall’aglio g and maggy a (1996), ‘HPP strawberry pro- ducts: an example of processing line’, in Hayashi R and Balny C (eds), High Pressure Bioscience and Biotechnology, Amsterdam, Elsevier Science B V, 445–50 sancho f, lambert y, demazeau g, largeteau a, bouvier j m and narbonne j f (1999), ‘Effect of ultra-high hydrostatic pressure on hydrosoluble vitamins’, J Food Eng, 39, 247–53 sch?berl h, ru? w, meyer-pittroff r, roth f x and kirchgessner m (1999), ‘Comparative Studies concerning the digestibility of raw, heated and high pressure treated foods in young pigs and in vitro’, in Ludwig H (ed), Advances in High Pressure Bioscience and Biotechnology, Heidelberg, Springer, 385–8 severini c, romani s, dall’aglio g, rovere p, conte l and lerici c r (1997), ‘High pressure effects on oxidation of extra virgin olive oils’, It J Food Sci, 3(9), 183– 91 sierra 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pigments’, in Autio K (ed), ‘Fresh novel foods by high pressure’, VTT Symposium 186, Espoo, Finland, Technical Research Centre of Finland, 83–95 452 The nutrition handbook for food processors tauscher b (1999), ‘Chemical Reactions of Food Components Under High Hydrostatic Pressure’, in Ludwig H (ed), Advances in High Pressure Bioscience and Biotechnol- ogy, Heidelberg, Springer, 363–6 van den broeck i, ludikhuyze l, weemaes c, van loey a and hendrickx m (1998), ‘Kinetics for isobaric-isothermal degradation of l-ascorbic acid’, J Agric Food Chem, 46, 2001–6 van loey a, ooms v, weemaes c, van den broeck i, ludikhuyze l, indrawati, denys s and hendrickx m (1998), ‘Thermal and pressure-temperature degradation of chloro- phyll in broccoli (Brassica oleracea L. italica) juice: a kinetic study’, J Agric Food Chem, 46(12), 2785–92 wada s (1992), ‘Quality and lipid change of sardine meat by high pressure treatment’, in Balny C, Hayashi R, Heremans K and Masson P (eds), High Pressure and Biotech- nology 224, Montrouge, John Libbey Eurotext, 235–8 wada s and ogawa y (1996), ‘High presure effects on lipid degradation: myoglobin change and water holding capacity’, in Hayashi R and Balny C, High Pressure Bio- science and Biotechnology, Amsterdam, Elsevier Science B V, 351–6 wuytack e (1999), Pressure-induced germination and inactivation of Bacillus subtilis spores, Doctoral dissertation no. 404, Katholieke Universiteit Leuven, Leuven, Belgium yengcand lin h t (1996), ‘Comparison of high pressure treatment and thermal pasteurisation on the quality and shelf life of guava puree’, Int J Food Sci Technol, 31, 205–13 zimmerman f and bergman c (1993), ‘Isostatic high-pressure equipment for food preser- vation’, Food Technol, 47(6), 162–3 21.12 Appendices Appendix 21.1 Tentative list of universities actively involved in high pressure research in the last 10 years particularly in the field of bioscience, food science and chemistry JAPAN Department Institution City / Anan College of Anan Technology Department of Food Science Rakuno Gakuen Ebetsu University Department of Applied Chemistry Fukui University Fukui Department of Food and Nutrition Nakamura Gakuen Fukuoka University Department of Nutrition Morphology Nakamura Gakuen Fukuoka University Department of Applied Science Kyushu University Fukuoka Laboratory of biochemistry, Department Fukuoka University Fukuoka of Chemistry Department of Applied Biological Hiroshima University Higashihiroshima Science Department of Applied Chemistry Kagoshima University Kagoshima Department of Chemistry Kobe University Kobe Department of Chemical Engineering Kobe University Kobe The Graduate School of Science and Kobe University Kobe Technology High pressure processing 453 JAPAN Continued Department Institution City Department of Home Economics Konan Women’s Kobe University Laboratory of Biochemistry Kobe Yamate College Kobe Division of Applied Life Sciences Kyoto University Kyoto Institute of Chemical Research Kyoto University Kyoto Department of Agricultural Chemistry Kyoto University Kyoto (Research Institute for Food Science) Department of Chemistry Kyoto University Kyoto Department of Molecular Engineering Kyoto University Kyoto Department of Polymer Science and Kyoto Institute of Kyoto Engineering Technology Department of Applied Biology Kyoto Institute of Kyoto Technology Department of Chemistry Ritsumeikan University Kyoto Department of Science Kyoto University of Kyoto Education Department of Industrial Science Kyoto University of Kyoto Education Faculty of Agriculture Meijo University Nagoya Faculty of Agriculture Nagoya University Nagoya Department of Food Science and Nagoya University Nagoya Technology Department of Applied Biochemistry University of Niigata Niigata Department of Biosystem Science University of Niigata Niigata Department of Chemistry Nagaoka University of Niigata Technology Electron Microscopic Laboratory University of Niigata Niigata Department of Nutrition Science Okayama Prefectural Okayama University Laboratory of Food Science and Hagoromo-Gakuen Sakai Nutrition College Institute for Chemical Reaction Science Tohoku University Sendai Department of Chemistry Ritsumeikan University Shiga Department of Applied Biochemistry Utsunomiya University Tochigi Department of Chemical Science and University of Tokushima Technology Tokushima Department of Biological Science and University of Tokushima Technology Tokushima Department of Biology Japan Women’s Tokyo University Department of Chemical and Biological Japan Women’s Tokyo Sciences University Food Science and Technology Nihon University Tokyo Department of Biological Chemistry Nihon University Tokyo Food Processing Centre Tokyo University of Tokyo Agriculture Department of Food Science and Tokyo University of Tokyo Technology Fisheries Faculty of Technology Tokyo University of Tokyo Agriculture and Technology 454 The nutrition handbook for food processors JAPAN Continued Department Institution City School of Human Life and Ochanomizu University Tokyo Environmental Science Faculty of Home Economics Ochanomizu University Tokyo Biotechnology Research Centre Toyama Prefectural Toyama University Department of Applied Biochemistry Utsunomiya University Utsunomiya EUROPE Department Institution City Country Laboratory of Food Katholieke Leuven Belgium Technology Universiteit Leuven Laboratory of Food Katholieke Leuven Belgium Microbiology Universiteit Leuven Laboratory for Chemical Katholieke Leuven Belgium and Biological Universiteit Leuven Dynamics Unité de Technologie des Gembloux Agricultural Gembloux Belgium Industries Agro- University Alimentaires Department of Food Ghent University Ghent Belgium Technology and Nutrition Department of Food Czech Academy of Prague Czech Preservation and Meat Sciences Republic Technology Department of Dairy and Royal Veterinary and Frederiksberg Denmark Food Science Agricultural University Institute of Biochemistry Odense University Odense Denmark LBPA Ecole Normale Cachan France Supérieure de Cachan Laboratoire de Génie des ENSBANA – Dijon France Procédés Alimentaires University of et Biotechnologiques Bourgogne Laboratoire de Génie University of La La Rochelle France Protéique et Cellulaire Rochelle Unité de Biochimie et University of Montpellier France Technologie Montpellier Alimentaires Genie des Procedes école Nationale Nantes France Alimentaires (GEPEA) d’Ingénieurs des Techniques des Industries Agricoles et Alimentaires Laboratoire de Biochimie Institut Supérieure de Talence France et Technologies des Technologie Aliments Alimentaires de Bordeaux High pressure processing 455 EUROPE Continued Department Institution City Country Interface Haute Pression école Nationale Talence – France Supérieure Bordeaux Bordeaux de Chimie et de Physique de Bordeaux Department of Food Technische Universit?t Berlin Germany Biotechnology and Berlin Food Process Engineering Department of Chemistry University of Dortmund Germany Dortmund Institute of Physiology University of Heidelberg Germany Heidelberg Institute of University of Heidelberg Germany Pharmaceutical Heidelberg Technology and Biopharmacy Institute of Inorganic University of Kiel Kiel Germany Chemistry Institute of Food Process Technische Universit?t Freising- Germany Engineering München Weihenstephan Lehrstuhl für Technische Universit?t Freising Germany Fluidmechanik und München Prozessautomation Lehrstuhl für Energie- Technische Universit?t Freising Germany und Umwelttechnik der München Lebensmittelindustrie Institut für Technische Universit?t Freising Germany Ern?hrungsphysiologie München Department of Molecular Max Planck Institute G?ttingen Germany Biology for Biophysical Chemistry Lehrstuhl für Technische Technische Universit?t Munchen Germany Mikrobiologie München Laboratory for Food National Technical Athens Greece Chemistry and University of Technology Athens Department of Biophysics Semmelweis Budapest Hungary and Radiation Biology University Dipartimento di Scienze University of Milan Milan Italy Molecolari Agroalimentari Dipt. Di Fisiologia e Università degli Studi Milan Italy Biochimica Generali Istituto di Impianti University of Padova Padova Italy Chimici Instituto di Biofisica CNR Pisa Italy Dipartimento di Scienze University of Udine Udine Italy degli Alimenti 456 The nutrition handbook for food processors EUROPE Continued Department Institution City Country Istituto Policattedra University of Verona Verona Italy Kluyver Laboratory for Technische Delft The Biotechnology Universiteit Delft Netherlands Department of Food University of Olsztyn Poland Technology Agriculture and Technology Department of Food Warsaw Agricultural Warsaw Poland Hygiene University Department of Chemistry University of Aveiro Aveiro Portugal Department of Chemistry Moscow State Moscow Russia University Faculty of Chemistry and University of Maribor Maribor Slovenia Chemical Engineering Tecnologia dels Aliments Universitat Autònoma Bellaterra Spain (CeRTA) de Barcelona Protein Engineering University of Girona Girona Spain Laboratory Laboratory of Physical ETH-Zentrum Zurich Switzerland Chemistry Institut de Chimie University of Lausanne Switzerland Minérale et Analytique Lausanne (BCH) Department of Agriculture The Queen’s Belfast UK for Northern Ireland University of Belfast Department of Bioscience University of Glasgow UK and Biotechnology Strathclyde Department of Chemical Imperial College of London UK Engineering and Science, Technology Chemical Technology and Medicine School of Food University of Reading UK Biosciences Reading Department of Chemistry University of Reading UK Reading Department of University of Scotland UK Biomedical Sciences Aberdeen School of Biosciences University of Surrey Surrey UK Procter Department of University of Leeds Leeds UK Food Science REST OF THE WORLD Department Institution City/States Country Department of Pharmacology University of Western Nedlands Australia Australia Department of Biochemistry Federal University of Rio de Brazil Rio de Janeiro Janeiro High pressure processing 457 REST OF THE WORLD Continued Department Institution City/States Country Department of Medical Federal University of Rio de Brazil Biochemistry Rio de Janeiro Janeiro Department of Biochemistry State University of Campinas Brazil Campinas (Sao Paulo) Department of Food Science and McGill University Montreal Canada Agricultural Chemistry (Quebec) Scientific Centre of Radiobiology The Georgian Tbilisi Republic of and Radiation Ecology Academy of Georgia Sciences Department of Chemical University of Berkeley USA Engineering California Center of Marine Biotechnology University of Baltimore USA Maryland Biotechnology Institute Department of Food Science and Oregon State Corvallis USA Technology University Department of Food Science and Ohio State University Columbus USA Technology Department of Biochemistry UT South western Dallas USA Medical Centre Food Science and Human Nutrition University of Florida Gainesville USA Centre for Marine Biotechnology University of La Jolla USA and Biomedicine California SCRIPPS, Marine Biology University of La Jolla USA Research California Citrus Research and Education University of Florida Lake Alfred USA Centre Department of Animal and Food University of Newark USA Sciences Delaware Department of Chemistry Rutgers University New Jersey USA Centre for Nonthermal Processing Washington State Pullman USA of Food (CNPF) University Department of Biological Systems Washington State Pullman USA Engineering University Department of Food Science and Washington State Pullman USA Human Nutrition University Food Science Department North Carolina State Raleigh USA University Department of Microbiology and University of Rochester USA Immunology Rochester Department of Pharmaceutical University of San USA Chemistry California Francisco Beckman Institute for Advanced University of Illinois Urbana USA Science and Technology 458 The nutrition handbook for food processors Appendix 21.2 Tentative list of research centres, government institutions and industries actively involved in high pressure research in the last 10 years JAPAN Institution City/Prefecture Pokka Corporation Achi Department of Research and Development, Nihon Shokken Co. Ltd. Ehime Maruto Sangyo Co. Ltd. Fukuoka Department of Research and Development, Ichiban Foods Co. Ltd. Fukuoka Frozen Foods R&D Centre, Ajinomoto Frozen Foods Co. Ltd. Gunma Mitsubishi Heavy Industries Ltd., Hiroshima Machinery Works Hiroshima Hiroshima Prefectural Food Technological Research Centre Hiroshima-shi Research and Development Centre, Nippon Meat Packers, Inc. Hyogo Manufacturing Service Department, Nestlá Japan Ltd. Hyogo Mechanical Engineering Research Laboratory, Kobe Steel Ltd. Hyogo SR Structural Research Group Hyogo Toyo Institute of Technology Hyogo Biotechnology Research Laboratory, Kobe Steel Ltd. Ibaraki National Institute of Bioscience and Human Technology, Agency of Ibaraki Industrial Science and Technology Research and Development Centre, Nippon Meat Packers, Inc. Ibaraki Food Product Technologies, Central Research Laboratories, Kanagawa Ajinomoto Co. Ltd. Food and Drug Safety Centre Kanagawa Takanshi Milk Kanagawa Kato Brothers Honey Co. Ltd. Kanagawa Kumamoto Industrial Research Institute (KIRI) Kumamoto Hondamisohonten Co. Ltd. Kyoto Hishiroku Co. Ltd. Kyoto Teramecs Co. Ltd. Kyoto Miyazaki Food Processing R&D Centre Miyazaki Miyazaki Prefectural Institute for Public Health and Environment Miyazaki Marui Co. Ltd. Nagano Food Technology Research Institute of Nagano Prefecture Nagano Industrial Technology Centre of Nagasaki Prefecture Nagasaki Food Technology Research Institute of Nagano Prefecture Nagoya Mutter Ham Co. Ltd. Nagoya Mitsubishi Rayon Engineering Co. Ltd., Aichi Nagoya Research Institute, Echigo Seika Co. Ltd. Niigata Meidi-Ya Food Factory Osaka San-Ei Gen FFI, Inc. Osaka Yamamoto Suiatu Kogyosho Co. Ltd. Osaka Department of Sales Engineering, Yamamoto Suiatu Kogyosho Osaka Co. Ltd. Nitta Gelatin Inc Osaka Technology and Research Institute, Snow Brand Milk Products Saitama Co. Ltd. Packaging Research Institute, Dai Nippon Printing Co. Ltd. Sayama Technology Development Labs, Meiji Seika Kaisha Ltd. Saitama Packaging Research Laboratory, Toppan Printing Co. Ltd. Saitama Industrial Research Institute of Shiga prefecture Shiga Research Laboratory Takara Shuzo Co. Ltd. Shiga High pressure processing 459 JAPAN Continued Institution City/Prefecture Biochemical Division, Yaizu Suisan Kagaku Industry Co. Ltd. Shizuoka Research Laboratory, Yamamasa Co. Ltd. Shizuoka Research Institute Kagome Co. Ltd. Tochigi-ken Oriental Yeast Co. Ltd. Tokyo Research Institute of Q.P. Corporation Tokyo Central Research Lab., Nippon Suisan Kaisha Ltd. Tokyo The Japanese R&D Association for High Pressure Technology in Tokyo Food Industry Taiyo Central R&D Institute, Taiyo Fishery Co. Ltd. Tokyo Nippon Surio Denshi K.K. (Framatome Corp.) Tokyo Tetra Pak Tokyo Food Industrial Research Institute Tottori Sugino Machine Ltd. Toyama Toyama Food Research Institute Toyama National Institute for Materials and Chemical Research Tuskuba National Institute of Bioscience and Human Technology Tuskuba DEEP STAR group, Japan Marine Science and Technology Centre Yokosuka (JAMSTEC) National Research Institute of Fisheries Science Yokohama Wakayama Agricultural Processing Research Corporation Wakayama EUROPE Institution City Country FMC Food Machinery Corporation Europe N.V. Sint Niklaas Belgium Engineered Pressure Systems International NV Temse Belgium (EPSI) Biotechnology and Food Research, Technical Helsinki Finland Research Centre of Finland (VTT) Hautes Pressions Technologies (until 2000) Bar le Duc France EPL-AGRO (until 2000) Bar le Duc France Pampryl Guadeloupe France Centre Technique de la Conservation des Produits Dury France Agricoles CLEXTRAL Firminy France European Synchrotron Radiation Facility Grenoble France Centre de Recherches du Service de Santé des Armées La Tronche France Institute for Health and Medical Research Montpellier France (INSERM)U128 Gec ALSTHOM ACB Nantes France Institute for Health and Medical Research Paris France (INSERM)U310 Equipe de Recherche Agroalimentaire Périgourdine Périqueux France (ERAP) National Institute for Agricultural Research (INRA) Toulouse France Max Delbrück Center for Molecular Medicine Berlin Germany Nutronova GmbH Frankfurt Germany UHDE Hochdrucktechik GmbH Hagen Germany 460 The nutrition handbook for food processors EUROPE Continued Institution City Country Institute of Chemistry and Biology, Federal Research Karlsruhe Germany Centre for Nutrition (BFE) Federal Dairy Research Centre Kiel Germany Max Planck Institute Mainz Germany Experimental Station for the Food Preserving Parma Italy Industry Flow Pressure Systems (former ABB Pressure Milan Italy Systems) Exenia Group S.r.l Albignasego Italy Agrotechnological Research Institute (ATO-DLO) Wageningen The Netherlands Unilever Research Laboratorium Vlaardingen The Netherlands State Scientific Centre of Russian Federation Moscow Russia Flow Pressure Systems (former ABB Pressure Vaesteraas Sweden Systems) Nestlé Research Centre, Nestec Ltd. Lausanne Switzerland National Institute of Hygiene Warsaw Poland Institute of Bioorganic Chemistry, Polish Academy of Poznan Poland Sciences Institute of Agricultural and Food Biotechnology, Warsaw Poland Polish Academy of Sciences High Pressure Research Centre, UNIPRESS, Polish Warsaw Poland Academy of Sciences Institute of Organic Chemistry, Polish Academy of Warsaw Poland Sciences Institute of Biomedical Chemistry, RAMS Moscow Russia State Scientific Centre of Russian Federation Moscow Russia Space Biomedical Centre for Training and Research Moscow Russia Union ‘PLASTPOLYMER’ St Petersburg Russia Institute for High Pressure Physics, Russian Academy Troitsk Russia of Sciences Instituto del Frío (CSIC), Ciudad University Madrid Spain Esteban Espuna Olot Spain Stansted Fluid Power Ltd. Essex UK Campden and Chorleywood Food Research Chipping UK Association (CCFRA) Campden Institute of Food Research Norwich UK Donetsk Physics and Technology Institute, National Donetsk Ukraine Ukrainian Academy of Sciences UNITED STATES, CANADA AND SOUTH AMERICA Institution City Country Food Research and Development Centre St. Hyacinthe Canada (Quebec) National Centre for Food Safety and Technology (NCFST) Chicago USA Avomex Keller USA Flow International Corporation Washington USA BMA Laboratories, Inc. Woburn USA BioSeq, Inc. Woburn USA High pressure processing 461