Handbook of Food Preservation

A wide range of quality characteristics can be obtained by running the dryer within wide ranges of temperature and relative humidity. The use of modified atmospheres for drying of sensitive materials such as food products is another important potential aspect of heat pump drying technology. Structural changes in food during drying are usually studied by microscopy. Multiplication of microorganisms should not occur in properly processed dehydrated foods, but they are not immune to other types of food spoilage. The behavior of drying oils toward atmospheric oxygen is well known, and oxidation is a serious problem for commercial drying of fatty fish and seafood. The elimination of oxygen from foods can reduce oxidation, but the oxygen concentration must be very low to have an effect. The effect of water on the destruction of the protective food structure in some specific dehydrated foods is probably involved in the prevention of lipid oxidation in heated meat systems.