1
Origins, Growth and
Potential of Dehydration
ORIGINS
The origins of dehydration go back into antiquity The preservation of
food by drying has been an art for centuries but it is only in the middle of the
present century that the art has been translated into terms of technology
The old methods of utilising the sun and wind to evaporate water
from foodstuffs, however, still prevail in many parts of the world, and are
likely to do so for years to come, for the centuries-old crafts are not easily
lost, even in the age of technology.
In the coastal villages of West Africa, fishermen still salt down their
catch and hang it in the sun to dry, making what is locally, and somewhat
understandably, known as 'stink fish'. To Europeans, this designation is
perhaps an understatement, and most would regard it as the highest built-in
ptomaine poison risk imaginable. In spite of this, stink fish is highly prized
by the African and, added to cassava mot meal or rice, it provides a protein
constituent in what would otherwise be an unbalanced carbohydrate diet.
The conditions of preparation would appear to Western eyes to be devoid of
the simplest requirements of hygiene and process control, yet the author has
never heard of any untoward effects arising from its consumption.
In the cattle raising territories of South America the ranchers have
been sun-drying beef in a similar fashion for years. Probably this was a
technique originated by the Indians, and, as recently as the early part of the
present century, it was not uncommon to see a side of dried beef hanging
5
outside the entrance to a ranch, for migrant workers and itinerants passing
by to help themselves to a few slivers, to give them sustenance for their
joumey. It is more than possible that, for economic reasons, this custom no
longer prevails but it was once quite common in the Argentine and Brazil.
Naturally dried fish, preserved by traditional and ancient methods, is
still seen in Scandinavia and other European countries where fishing is an
important industry, and it is still consumed there, as are the more
scientifically processed fish products.
Dried ling, or 'stock-fish' , is a common sight hanging outside the
village grocer's shop in the remoter parts of Ireland away from the sea coast.
It forms a regular part of the Catholic diet on fast days, in the absence of fresh
fish, and, in some areas in the West of Ireland, is even preferred to the more
sophisticated types of canned and frozen fish.
The sun-drying of fruit also goes back for centuries and is still
practised today, particularly where labour is cheap and abundant, and
climatic conditions are favourable.
It will, perhaps, be demonstrated in the latter chapters that to simulate
the effects of these natural forces of sun and wind can, indeed, be a costly
procedure, and when we think of translating the old crafts into scientific
processes, then it is essential to probe very carefully into the economics of
the undertaking and this is considered in some detail in Chapter 13.
GROWTH
The transition from craft to technology can perhaps be traced to the
period during World War 1 when considerable quantities of dried vegetables
and soup were shipped to the Armed Forces in Europe from the US and, to a
lesser extent, from Britain. Some commercial development in dehydrated
foods, particularly vegetables, had previously been achieved in the UK in
the mid-nineteenth century, when dehydrated carrots and potatoes were
supplied to the Royal Navy, and to troops in the Crimea. At about the same
time, some early research was carried out into the manufacture of dried
milk.
Between the two World Wars, however, little progress appears to have
been made in gaining domestic consumer acceptance of dehydrated foods.
Their value under wartime conditions was undeniable but the technology
was not sufficiently advanced to make any impact on the public in general.
Possibly the already improved techniques in canning impeded the progress
of dehydration as a popular means of conserving food.
Further development obviously depended on fundamental research
to give a better theoretical understanding of the underlying mechanisms,
and on the creation of objective methods for assessing flavour and texture
6
changes which are directly related to human sensory evaluation.
World War 2 focused more attention on the industry, as the Allies were
engaged this time in a type of warfare involving transportation and
deployment of men and supplies over infinitely vaster areas than in World
War 1. Dehydrated foods enabled many of these problems of transportation
and storage to be solved, in that dried vegetables, meats and soups, pruduced
for the Armed Services' use, occupied only a fraction of the space taken up
by canned and fresh food, and the weight factor was similarly reduced.
A striking example of this weight/bulk economy is provided by
cabbage - a vegetable with over 90 percent water content. In dehydrated
form, and compressed (as was specified by the Services), it weighs only one
twentieth as much as raw cabbage, and occupies about one fortieth of the
storage space.
Cabbage, carrots and potatoes figured very prominently in the
dehydration programme set up by the British Ministry of Food in the early
part of 1941 and, by 1943, there were several factories operating in the UK,
the total production of which was taken by the Ministry. Quality
specifications were laid down by the Government's technical officers and
close liaison was maintained at all times with the factory technicians and
management. In all, some sixteen major plants and about eight smaller units
came into vegetable dehydration in this period, contributing very materially
to the War effort.
Experimental work was also carried out at this time on dried soup and
dehydrated meat at a pilot plant in Northern Ireland and on dehydrated
herrings in Scotland. These experiments all led eventually to commercial
production of supplies for the Forces. Throughout this time, close contact
was maintained between the Ministry and those in other parts of the world
who were similarly developing dehydration, particularly in the US and
Canada. In 1942 a joint Ministry of Food-US Dept of Agriculture mission was
appointed by the Combined Food Board to survey the vegetable dehydration
industry in America and Canada, and to assess both the curxent and postwar
prospects.
In 1943, a mission, including both British and American members,
toured Africa to stimulate the dehydration industry and to form a liaison
with the many workers in the field. In the following year a similar mission
visited India with the same aims in view and, as a result of all these contacts,
a pool of technical information was amassed and new ideas were diffused,
which provided a stimulus for further valuable experimental work that, in
the ensuing years, was to provide the cornerstone for a new and important
industry.
The transition from a wartime industry to a viable commercial
7
undertaking in peacetime was, however, slow and it was the 1950’s before
any significant progress was made. Most of the British dehydration plants
ceased to operate when the Services’ requirements diminished at the end of
the War, and it was left to a handful of companies to press on with the
valuable research and experimentation, barely recognising, at that difficult
time, the potential which was going to open up in the ensuing two decades.
Contacts with enthusiastic workers in the US were renewed, and now
liaison with Europe was again possible. The first major breakthrough to
retail consumer acceptance of dehydrated foods was, however, to occur in
America, where Potato Granules hit the market in a big way. The interest in
this product was, of course, stimulated again in a military context by the
hostilities in Korea, and once again the manufacturing experience gained in
wartime conditions played an important part in the improvement of
technology and in the upgrading of the quality of the end-product in many
ways.
In 1954, the research workers Cording and Willard of the Engineering
and Development Laboratory in Philadelphia, produced Potato Flakes by
using the technique of drum drying. The resultant product was a mashed
potato almost indistinguishable in taste and texture from that of a freshly
mashed potato. This was a significant step forward for the new potato
processing industry, which was seeking the American consumer market.
Simultaneously, considerable technical advances were made in the
manufacture of potato granules, on both sides of the Atlantic, and in the
1958-59 processing season in the US, 75,000,0001b of granules were produced,
utilising 300,000 tons of potatoes, or 3 percent of the North American crop
that year.
Meat dehydration also gained some impetus this time, particularly
the processing of chicken granules for soup. Chicken Noodle was one of the
first varieties to be promoted and to receive wide acceptance in the retail
market, which had hitherto been dominated by canned soups.
The success of these novel convenience packs, with the advantages of
low weight, low volume and portability, opened the way for the commercial
pioneers of dehydration to improve the techniques of drying and packing of
a wider range of vegetables and meats, than was ever contemplated during
the War, in a form suitable for and attractive to soup manufacturers.
The latter were not always dehydrators themselves but died for their
basic ingredients on the specialists in drying, who now recognised the
potential for an ever increasing range of products. Demand now went far
beyond potatoes, carrots and cabbage, and extended to the more exotic field
of asparagus, mushrooms, red and green peppers, celery, leeks, tomatoes,
French beans, garden peas, celeriac, courgettes, spinach and chillies.
8
Dehydrated 'packet' soups were undoubtedly here to stay from the
1950's onwards. The trend towards shopping in the supermarkets and chain
stores, which involved carrying the purchases home, highlighted, to the
housewife, the great convenience of the 40g packet against the 400g can.
Some of the major soup manufacturers originated from the Continent
where traditional culinary skill was displayed in the formulation of soups,
and a considerable service was rendered to the dehydration industry by the
high standard of quality maintained in this field. Promotion of these
products is now worldwide, and the future potential assured if quality is
maintained.
POTENTIAL
In the mid-70's the potential for vegetable dehydration in the United
Kingdom appeared to experience some set-backs, and failed to achieve some
of the earlier promised forecasts.
This applied mainly to the demand for domestic packs of individual
products, such as green peas, onions and mixed vegetables.
Potato granules were vigorously marketed, supported by advertising
in the National media, and held their share of the convenience food market
better than most other products but currently there is only one major granule
producer left in the UK and some 2000 tonnes are imported each year. The
greater part of this tonnage comes from the Netherlands, the Federal
Republic of Germany, Belgium and France. A small tonnage in 1986 came
from Poland and Sweden. The USA, once a major source of imports into the
UK, has shipped very little, due in the main to the weakness of sterling
against the dollar since 1976, when the rate dropped from a high of $2.55 to
the pound in 1971 to $1.80 in 1976. There was a temporary rally in the value
of sterling against the dollar in 1979/81 but since 1976 other European origins
for potato granules have developed strongly and have taken up the slack
arising from the decline in home production in the last decade and American
imports.
Potato granules still hold a substantial share of shelf space in the
supermarkets where the domestic market is vigomusly promoted but an
ever increasing tonnage has now found its way into value-added products
in the form of an infinite variety of potatebased snack foods, soups, sauces
and garnishes, and ethnic speciality foods. Taking the straight sales of
granules plus the tonnage used as a constituent of other dehydrated foods, it
must be recorded that in this context the trade has expanded since 1970.
Where impetus has been lost, however, is in the case of the most
popular green vegetable - the 'garden' pea - which in the 70's looked set to
compete very seriously with the frozen pea. In spite of energetic promotion,
9
it failed to gain the housewife’s total support, in that it did not live up to
some producers’ claims that the dehydrated pea reconstituted immediately
by immersion in boiling water, without soaking or cooking. The promise of
an instant cooked pea was not realised. The brand leaders in frozen foods
were producing a frozen pea which fully cooked after three minutes
simmering and, in claiming a better cooking performance for the dehydrated
pea, some credibility was lost. Cumnt packs on the domestic market now
recommend 15 minutes simmering to completely rehydrate and tenderise
dehydrated peas, and this is nearer to reality but popularity appears to have
waned.
Enormous efforts have been made by the growers and processors to
achieve parity with the frozen pea, by selecting cultivars particularly suited
to the dehydrator but, with conventional hot-air drying, it is a difficult task.
Both the freezer and the dehydrator set the same quality standard at
the farm gate, in that both call for a pea with a tenderometer reading of 90-
100 on the scale, with round-the-clock vining to ensure a continuous flow of
ultra-fresh peas into the plant. However, tenderometer readings can only be
a guide to quality, not an assurance, as a random check from each delivery at
the farm gate and the factory gate can only monitor a fraction of the bulk.
Tenderness and maturity can vary from row to row and field to field, and
can even be inconsistent in a single pod where peas at the end of the pod will
vary in maturity from those in the middle. An amalgam will therefore give a
mean average tenderometer reading but, when the bulk goes into process,
the freezing operation is far more flexible in dealing with small variations of
maturity, whereas in dehydration even a microscopic deviation can give rise
to ‘case hardening’ of the outer membrane of the pea and the denaturing of
the protein, which will inhibit full reconstitution and induce wrinkling.
The only safeguard is to apply floatation quality graders in the factory
but even this is occasionally over-ridden by an imbalance of drying
temperatures in the drying cycle, as the latter have to be harmonised so very
accurately to preserve the delicate texture of the freshly vined pea. There is
less margin for emr in temperature control at every stage of the drying cycle
than with any other vegetable.
The vagaries of the British climate invariably pose some threat to the
pea harvest, which at best only lasts six weeks, and sometimes as little as
five. A hot season can be equally as disastrous as a wet one, in that
progressive sowings over-ride one another and, in 24 hours, fields of peas at
an acceptable tenderometer reading can soar right over the top in that period
of time, making them unacceptable to the processor. Conversely in a season
of persistent rain, when heavy viners become bogged down and immobilised
in flooded fields, thousands of tons of produce can be lost, and the
IO
dehydrator's programme and the growers' bank balance become a disaster
area. The 1987 pea season was, for this very reason, the worst for 30 years,
and affected the freezers and canners equally badly.
In the course of experiencing over 50 pea s easons in the UK the author
has concluded that there is no such phenomenon as a 'normal' pea season,
and the impact on the dehydrator is perhaps greater than on the canner or
freezer, which may explain why in the 1987 season only one company in the
United Kingdom remained in pea dehydration, using hot air drying
methods, and consequently the market demands can only be met by imports
from those few origins where the quality of green peas is normally acceptable
-New Zealand, South Africa and the Republic of Ireland.
Freeze drying produces a moE acceptable quality of pea, subject to a
high standard of raw material but the pmcess is expensive and, in context of
vegetables, only one processor appears to be operating currently in Britain
by this method.
The development of dehydration in overseas locations has been
widely monitored over the period 1970-1987 by the author, through
Feasibility Studies for new ventures, and visits to existing factories in India,
Africa and Eastern Europe. Low world prices in the 1970's precluded much
investment in new plant and machinery in factories which had been
established for some years, which resulted in a decline in the quality of their
products or, in some cases in Eastern Europe, a temporary cessation of
production of their principal exportable product - dehydrated onions-which
rank overall as the most important vegetable imported into Western Europe
from all origins.
Right: The author
examining a heavy crop of
Ventura tomtoes.
Up to 1980 the c.i.f. price for onions from Egypt, India and Eastern
Europe, shipped to Western Europe, had not exceeded ￡950 per tonne, and it
was not until the mid-80s that prices moved into the area of ￡1300-￡1500,
which made viability more of a reality, and, in addition to assisting existing
producers, it began to encourage new ventures.
Onion dehydration facto ry - Nasik, India
Where the climate is suitable for the commercial growing of
dehydrating varieties of onions, ie, cultivars with high total solids, white
flesh and high pungency there is some validity in looking carefully into the
potential for setting up a dehydration plant, because onions will invariably
provide a substantial period of production run, and will combine with other
vegetables, compatible with the climate, to give a throughput for the year
which will meet the economic parameters to which reference was made in
the Preface to this edition. A product mix which might well be considered
would be onions, carrots, leeks, beans, cabbage, capsicums and tomatoes, all
of which, suitably comminuted, may find a market in Europe as constituents
in a large variety of value-added products.
The annexed TABLE 1.1 will indicate the countries which are currently
exporting dehydrated vegetables to the United Kingdom. Some stability in
world prices may well stimulate expansion in this trade in countries from
which the statistics show only token tonnages have been shipped. Some
origins in the developing regions obviously need some confidence in the
potential for export, and indeed many need an injection of new capital to
bring their plants up to date in order to comply with current quality
standards, and to engender more profitability.
The low prices prevailing in the 70s for the staple item of dehydrated
onions, for example, inhibited many factories from investing in new plant,
the cost of which was escalating at an alarming rate, whilst there was little
corresponding movement in the value on the market for the dehydrated
product.
Right: Manual hydrout
corm for onions
,
r-
One weakness in the asymmetry of this equation was perhaps the
efforts of the food machinery manufacturers to offer their overseas clients in
the developing countries plant which was too sophisticated for their needs
or their ability to absorb the intricacies of the newer technology which was
being introduced into food processing equipment. This undoubtedly slowed
down reinvestment in new plant with many of the smaller producers and,
apart from the problem of difficult exchange control restrictions and shortage
of hard currency there was little incentive for expatriate investors to inject
capital into overseas companies, when the cost of servicing this capital and
amortisation charges imposed an impossible burden on the factories' costs.
Exports from the USA, particularly onions, continued to flow but these
products always commanded a premium on account of their high quality to
which the trade had been accustomed for many years. For example, between
1976 to 1980 the average price for kibbled onions from origins other than the
USA was �750 per tonne c.i.f. European port, whereas American onions
13
varied between �1100 and E1600 per tonne.
The trade always maintained that a new source of origin would have
to sustain a quality equal to that of the American product consistently for
five years in order to merit parity in price.
In 1986, one of the more consistent Eastern European suppliers,
Hungary, was selling at �1294 per tonne, against the USA at �1344. France,
Holland, Germany, Yugoslavia and Turkey moved up into this price category,
ranging from �1210 to E1400 per tonne. Admittedly, the total tonnage shipped
from these five countries combined only equalled the tonnage from the USA
but the levelling up of the prices on the world market indicates that there has
been an improved consistency in the quality of the onions from these
European and Eastern countries, which augers well for the potential for
growth here.
Egypt almost equalled the American tonnage in 1986 as indicated in
TABLE 1.1 but the average price was only �908 per tonne.
From the author’s considerable experience of the dehydration industry
in Egypt, the considered opinion is that many of the old established State
controlled factories are suffering from the aforementioned lack of investment
in new plant, and the restructuring of the factories has not been given much
priority, in view of demands on the country’s reserves of hard currency for
more pressing developments.
The most encouraging development in Egypt is, of course, the facility
to operate in the private sector - an initiative promoted by the late President
Sadat. The quality of the Egyptian onion crop is excellent, as the export trade
in raw onions has been of paramount importance for many years, and it is
scrupulously controlled by the Ministry of Agriculture. With the advent of
privatisation therefore, the potential for developing the dehydrated onion
industry on higher quality levels is favourable. With the excellent raw
material grown in the Nile valley, the only ingredient needed is an infusion
of capital for new plant suited to the prevailing conditions in Egypt. It would
not be inopportune for the major European buyers of dehydrated onions to
regularly visit and monitor the factories engaged in the not inconsiderable
export business, so that they could assist the management in achieving that
extra element of quality which would bring the industry up a level that
would ensure better stability, in world price terms.
The method of restructuring and re-investing must be sensibly
undertaken. An old friend of the author, who is intimately connected with
the Freezing Industry in the USA, and has spent many years advising the
Indian shrimp packers on how they can up-date their factories to meet USDA
Food Laws applying to importations into America, made a wise comment
about throwing out old plant. His comment was ’The job ahead is to
14
modernise - you don't discard a motor car with 60,OOO miles on the clock for
an aeroplane -you just get a new car". In other words, improve what you
have.
With many operations in the developing countries, joint enterprise
schemes should be considered, so long as the expatriate investor can
contribute expertise as well as the venture capital, and also with the
provision that, on the successful establishment of the industry, any dividends
or participatory profits to which he may be entitled can be repatriated when
due.
TABLE 1.2 indicates the many sources of origin of dehydrated
vegetables not specifically classified in TABLE 1.1.
What is interesting is the number of countries now engaged in
dehydration which were not involved in 1970.
Included in the tonnages declared would probably be peas, green
beans, leeks, celery, beets, herbs, celeriac and a range of exotic vegetables
which, for Customs purposes, are not broken down under separate headings.
The figures, of course, refer only to imports into Great Britain, and
behind these could be substantial exports from the country of origin to other
countries in the world. For example, the figure for onions in TABLE 1.1
relates almost entirely to white onions, which are favoured almost
exclusively in the UK but very large tonnages of red onions are shipped
annually from Egypt to Russia and other Eastern Europe, similarly to Arab
countries, where India also does a trade in red onions, both fresh and dried.
So all the countries shown as suppliers on both tables are very much
larger producers than the figures would indicate by taking only one country
of importation.
To finalise on potential in the industry, it would be invidious to pre-
empt this development in any one country but over some ten years the
author visited three continents, which were not at that time seriously into
dehydration on a large scale. It appeared that the infra-structure was there,
the climatic conditions were favourable, and the only missing ingredient
was the return to normality of world market prices. In the wake of the oil
crisis of the 70s the inflated cost of new plant and machinery bore no relation
to the cash return from overseas markets for dehydrated fruits and
vegetables, and what was required was a decade of adjustment to bring
these two factors into some sort of equilibrium.
The countries surveyed were South America, India, Egypt and most of
Europe (East and West), and these warrant notice to a greater dege than
many other regions visited for the same reason, but in the years which have
since elapsed, there were difficulties, both political and financial still to be
solved.
15
CONCLUSIONS
In spite of the advance of technology, there is, nevertheless, still
something of an art in removing the water content from the products of
nature, and science has not yet solved all the problems. There are very few
constants in the raw materials of the trade, from season to season, and some
rudimentary skill is still needed to process some products satisfactorily, and
hand and experience have sometimes to take over from the machine. A
method, meticulously followed in one season may not necessarily apply to
the ensuing season, or with produce grown in a different geographical
location.
There are many types of dryer available, for example, for vegetables
but the end results can vary widely between one plant and another. Any one
machine of a number may be eminently suitable for a specific product but
the quality and success of the drying operation will still depend, to a great
degree, on the skill of the operator. In dehydration, the product undergoes
biophysical and biochemical changes, is subject to bacteriological hazards
and, to the uninitiated, can be notoriously unpredictable in many phases of
the rather lengthy process. The combination of science and some of the old
drying craft is, therefore, a prerequisite to success.
The methods described, therefore, are given merely as guidelines - a
considerable amount of skill and experience is needed to supplement mere
textbook knowledge.
Irrigation canaletto, Pernambuco Brazil
16
Table 1.1
United Kingdom Importation of Dehydrated Vegetables for 1986
Onions (Sliced/Kibbled/Powdered)
Origin Tonnes Value CIF
France 859
Netherlands 730
Germany (FR) 117
Italy 2
Irish Republic 11
Norway 37
Yugoslavia 43
Hungary 475
Denmark 27
Spain 41
Turkey 148
Poland 29
Egypt 2140
Israel 15
India 15
China 81
USA 2457
Peru 1
Others 39
-
7283 total �8.8million
17
Potato (Sliced /Cu t /Granules/Flakes)
Origin Tonnes Value CIF
France 158
Belgium/Luxembourg 40
Netherlands 485
Germany (FR) 782
Irish Republic 96
Spain 32
Finland 18
Switzerland 3
Poland 281
Israel 28
Canada 10
USA 173
Italy 20
-------
21 26 total El .7million
Mushrooms (Including Truffles)
Origin Tonnes Value CIF
France 88
Netherlands 14
Germany (FR) 69
Irish Republic 6
India 1
China 82
Taiwan 30
Hongkong 7
South Korea 3
Japan 12
USA 15
Italy 3
--------
330 total E2.6million
18
Tomatoes (Sliced/Kibbled/Powdered)
Origin Tonnes Value CIF
France 111
Netherlands 11
Germany (FR) 37
Italy 73
Spain 15
Morocco 54
South Africa 19
Chile 1
-
321 total E0.9million
Carrots (Diced /Flakes/ Powdered)
Origin Tonnes Value CIF
France 130
Netherlands 285
Italy 16
Germany (FR) 108
Irish Republic 55
Spain 22
Israel 165
USA 134
-
915 total E0.9million
Summary
Tonnes Value
Onions 7283 E8.8m.
Potatoes 2125 E1.7m
Mushrooms 330 E2.6m
Tomatoes 321 E0.9m
Carrots 915 �1,7m
Other Sorts 3200 E8.0m
14164 E23.7million
(Source: H.M. Customs and Excise)
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Table 1.2
United Kingdom Importation of Dehydrated Vegetables for 1986
(Other sorts not identified in Table 1.1)
Origin Tonnes Value CIF
France 250
Belgium/ Luxembourg 27
Netherlands 300
Germany (FR) 590
Irish Republic 62
Denmark 14
Greece 11
Spain 83
Switzerland 1
Yugoslavia 13
Turkey 189
Hungary 170
Morocco 1
181
4 Ghana
Italy 35
Norway 1
%YPt
Nigeria 8
Kenya 1
Cyprus 11
-
South Africa 283
Israel 105
Iran 73
Pakistan 21
India 8
Sri Lanka 1
Thailand 1
China 91
Taiwan 53
South Korea 1
Japan 14
New Zealand 11
USA 522
Dominica 1
Peru 1
Chile 29
Hongkong 33
----
3200 total E8.0million
This Total is included in the summary
partof Table 1.1
(Source H.M.Customs and Excise)
20
