Freezing is a form of preservation in which the temperature of the product is reduced to below its actual freezing point. In this case, some of its water content changes its form into ice crystals. Freezing, as a form of preservation, slows down food decay through the hindering of the growth of microorganisms. As we all know, the less water or moisture content prevents the rapid growth of bacteria.
The pattern on how freezing happens can be traced through the freezing curve. The first thing that happens is that the product cools until it reaches its freezing point then ice crystals begin to form. Synchronized to the formation of ice crystals, sensible heat and latent heat are removed. Solutes in the water will then start to crystallize until it reaches the eutectic temperature. It will continue to crystallize more until the temperature of the ice-water mixture falls to the same temperature as the freezer.
However, as we recognize how freezing and thawing can prolong the life of a substance, there are also effects of freezing to the products that are observed and studied. Some of these effects include a change in the pigments, taste and nutritional value, cell dehydration that further cause cell damage and it slowly degrades the quality of the product. Thawing, on the other hand, also causes cell damage, increases the risk of contamination by spoilage and it avoids overheating and excessive dehydration of food.
It is true that freezing prolongs the life of foods through making the bacterial growth slower. However, it should be considered, too, that freezing can also decrease the nutrients which we could obtain from the food we eat.
Atkins, P., Jones, L. Chemical Principles: The Quest for Insight (4th ed.). W. H. Freeman and Company. 2008. Print
Ott, J., Boerio, G. Chemical Thermodynamics: Advanced Applications. Academic Press. 2000. Print.