Frozen food chemistry

Since water is the principal constituent of most foods, "the process of freezing food is the process of freezing water." (2) Because different foods have variable water contents, each food substance has to be treated in a special way. "The prepared frozen food industry is not one industry at all – it is a score of industries and therefore it requires a score of histories." (1)

The manner in which liquid water turns to solid ice has been the subject of scientific research for more than a century. Even after ice crystals have been formed as the food is frozen, they may change on long-term storage. In addition, a variety of chemical reactions may also occur in frozen foods during storage. Thus the manner in which frozen food is stored and the way in which it is thawed can have a major impact on the quality of the final consumer product.

As in all food preservation techniques, freezing inhibits microbe activity, reducing bacteria and molds and their undesirable side effects. However, it does not kill all bacteria, and the industry quickly recognized that "freezing does not sterilize foods." (2)

Clearly, the commercial freezing of food products is not a simple process. The ignorance of the basic chemistry of the underlying processes on the part of many producers in the post war boom led to poor quality which was in part responsible for the refusal of the consumer to buy their products.

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Early methods of food preservation | A chance discovery | Frozen food chemistry | U.S. Agriculture turns to science | Frozen food research begins at WRRC | Defining "Quality"Chemical reactions at low temperaturesChlorophyll as a benchmark | Major scientific results from the T-TT programSocietal impact of the T-TT program | Landmark designation | Further reading and acknowledgments

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