ABSTRACT
Water is an important component of foods, even when they are “dry”. Dehydration is the application of heat under controlled conditions to remove by evaporation most of the water normally present in a food. Although dehydration is an important unit operation in food engineering and in the food processing industry, it is not extensively practised as such in the kitchen. In fact, there is no such kitchen apparatus as a “dehydrator”, even though some cooks utilize a sort of tray drier to remove the moisture from fruits and vegetables, as well as the kitchen oven. Cooks have many problems in dealing with moisture in foods because recipes are usually expressed by weight of ingredients, and this includes the water content. Another concept that cooks can use is hygroscopicity, or the capacity of a food to exchange water with air. This means that, for most foods, there is not a “single” moisture content.
