ABSTRACT
Freezing, one of the most common processes for the preservation of food, is effective for retaining the flavor, color, and nutritive value of food and is moderately effective for the preservation of texture. Compared with the thermal processing of foods, preservation by freezing is not based on microbial destruction but on the following two main mechanisms. The first mechanism is the decrease in enzyme and microbial activity that is a result of the low temperatures involved in the freezing process. The second mechanism is the conversion of water into ice, which reduces the availability of water activity for enzymatic and other degradative reactions in the food system. In the study of freezing, many theories have been developed, and the assumptions used for each approach greatly differ from one another. Experimental verification of the heat requirements for freezing requires the use of a differential scanning calorimeter, which is out of the scope of this laboratory practice.
