ABSTRACT
This chapter reviews the basic mechanisms involved during freezing and will define relevant terminology associated with the physics and chemistry of freezing. The process of food freezing as a means of preservation has gained widespread attention. Reduction of available water as ice, coupled with subzero temperatures, provides an environment that favors reduced chemical reactions and structural collapse of tissues, hence leading to increased storage stability. However, fundamental factors that accompany ice formation are relatively complex. The freezing process, which includes undercooling, nucleation, ice crystal propagation, and maturation, is strongly influenced by thermodynamics, kinetics, and product variables. Modification of these variables can ultimately lead to large changes in ice distribution and subsequent quality of the product. A thorough understanding of the fundamental aspects of freezing is necessary for a full appreciation of the benefits and disadvantages of freezing. Freeze-concentration has been demonstrated to enhance greatly the oxidation of ascorbic acid.
