Use of low temperature is the easiest, most convenient and least time-consuming method of preserving foods. Refrigeration/ freezing do not sterilize foods or destroy the microorganisms that cause spoilage. It simply slows the growth of microorganisms and the chemical and enzymatic changes that affect quality or cause spoilage.
Low temperature preservation is less effective as compared to thermal techniques of food preservation because microorganisms are more likely to be able to survive cold temperatures than hot temperatures. One of the problems related to use of freezing as a method of food preservation is that microorganisms are only deactivated and not killed, which may again become active while thawing. Similarly enzyme action is slowed but not stopped during freezing and these enzymes are responsible for colour and flavour changes and loss of nutrients during refrigerated storage.