ABSTRACT
The preservation of foods by drying is the time-honored and most common method used by communities and the food-processing industry. Heating of air by electric heater or flue gas is the conventional heating method used for drying processes used in foods. The mechanisms of moisture transfer depend mainly on the type or physicochemical state of food materials and the drying process. The vacuum drying of food involves subjecting it to a low pressure and a heating source. The potential of microwave-assisted vacuum and freeze-drying processes have also been explored for foods. Impingement drying is an old technology that has only recently been applied to food products. The main purpose of blanching is to inactivate the naturally occurring enzymes present in foods since enzymes are responsible for off-flavor development, discoloration or browning, deterioration of nutritional quality, and textural changes in food materials.
