Fresh flavours from dried food
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CTA. 1993. Fresh flavours from dried food. Spore 47. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/49227
The need to preserve food in times of plenty against the times of shortage has been faced from time immemorial. Probably the oldest and most usual method is air-drying which is simple fast and cheap. The only problem is that the appearance, texture...
The need to preserve food in times of plenty against the times of shortage has been faced from time immemorial. Probably the oldest and most usual method is air-drying which is simple fast and cheap. The only problem is that the appearance, texture and smell of the product changes and, even when reconstituted, rarely regains its original fresh flavour and appearance. Scientists at a laboratory in Cambridge, UK have been working on a substance called trehalose, a disaccharide made up of two glucose molecules that are linked by their reducing carbons. This makes trehalose a very stable, non-reducing sugar which is very soluble, chemically inert and biologically non-toxic colourless and virtually tasteless; properties which make the sugar ideal for the preservation of unstable biological molecules in natural food. As far as food was concerned the scientists concentrated on using trehalose dissolved in liquid or liquidized foods, where the trehalose could come into close contact with the food molecules. Blended fresh eggs dried with trehalose at 30\B0-50\B0C produced an odourless yellow-orange powder that could be stored at room temperature. On rebydration it was almost indistinguishable from a fresh egg. It was found that dehydrated pur\E9es of banana, strawberries, mangoes, avocados, apples and raspberries recovered the colour, flavour and smell of the original product when the dried powder was reconstituted. Fresh herbs that were dried after being dipped in trehalose solutions (area just as well. The characteristic aromas and flavours of many foods, especially fresh fruits and herbs, depend on the release of volatile aromatic molecules. The powders produced by using trehalose do not smell like the fresh product until water is added, after which they soon emit the unique aroma of fresh foodstuffs. Industrial methods of air-drying food are too harsh for the trehalose method so the scientists have developed their own drying techniques which are referred to as a captive atmosphere partial pressure (CAPP) drying; this is a method where very dry air is circulated to remove water vapour. This allows food to be dried at room temperatures and pressure, but has the added benefit that it does not remove volatiles other than water. Aromatic foodstuffs can be dried while retaining the greater part of their fresh volatile components. Bruce Roser and Camilo Colaco Quadra Research Foundation Trumpington Cambridge UK
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