The accelerated freeze-drying (AFD) method of food preservation / a report on some work of the Research Establishment and Experimental Factory of the Ministry of Agriculture, Fisheries and Food, Aberdeen, Scotland, between 1955 and 1960.

  • Great Britain. Ministry of Agriculture, Fisheries and Food.
Date:
1961
Catalogue details

Licence: Public Domain Mark

Credit: The accelerated freeze-drying (AFD) method of food preservation / a report on some work of the Research Establishment and Experimental Factory of the Ministry of Agriculture, Fisheries and Food, Aberdeen, Scotland, between 1955 and 1960. Source: Wellcome Collection.

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    it with melted fat, was adopted by the early settlers, and later by Arctic explorers. In 1780 in England the first patent for dehydration was granted to J. Graefer, who scalded vegetables in boiling salt water and then dried them in a heated room. The Royal Navy expedition which set out to search for Franklin in 1852 carried carrots and potatoes which had been dried in hot air for 20 to 30 hours. They were then compressed into cakes, wrapped in tinfoil and packed in air- tight cases of tin or zinc. They were not popular. One report said ‘The carrots require too much attention and therefore are not fit for sea service as rations’ and “The seamen did not take to the potatoes’. During the Crimean War an attempt was made to combat scurvy by using potatoes dried by Edwards’ patented process; which was to boil them, press them through small holes as fine threads and dry them on steam-heated plates. They were disliked as much as the carrot and meat powders also provided. The first World War saw a considerable production of air-dried vegetables and the second an extension to milk, eggs and meat. Hardly three years had elapsed after the 1939-45 war, however, when Commonwealth defence scientists realized, with some alarm, that both research and production on the dehydration of foodstuffs had, to all intents and purposes, ceased. From a defence viewpoint this was a matter of some importance, particularly to the United Kingdom, where the quantity of food necessarily imported each year contains something like 3 million tons of water, and any reduction in the water content would reduce the amount of shipping required. Since about three-quarters of meat and fish and possibly nine-tenths of fruit and vegetables are water the potential saving in packaging, storage and transportation resulting from dehydration could be immense. Dehydration has a further advantage, especially in periods of emergency, in that the biological material we call food is rendered considerably less perishable by this process. In the first instance, spoilage of foodstuffs by microbes is prevented by the removal of water and, secondly, the processes normally used for the dehydration of food stop the activity of the enzyme systems which are responsible for the metabolism of the living tissues. Under normal conditions these systems persist to a large extent in the food, causing first a ‘ripening’ and eventually a complete breakdown or rotting. Even the purely chemical reactions which can and do occur among the myriad components of the food are inhibited by lack of water. The result of dehydration is therefore a more or less stable food product, which can be kept without freezing or refrigeration. During the war this process, with its fundamental advantages in defence, had been applied on a large scale to the feeding of the populace, and on a relatively smaller scale, but no less significant, to the production of military rations for use throughout the world. Nevertheless, despite an advance in knowledge of blanching and sulphiting of vegetables, the war had ended with little more than a full realization of the problems and limitations of the process, when production and research ceased. It was in 1948 then, that the attention of Commonwealth countries was drawn to this hiatus in food research, and the advice to member-governments to stimulate further progress was acted upon by the British Government and resulted in the opening, in 1951, of the Research Establishment and Experi- mental Factory in Aberdeen. This latter provision was based on the hard-won experience of the war years, when it had been found difficult, if not impossible, to conduct adequate scientific experiments in a factory devoted to production.