Fundamentals of freezing processes

The freezing phenomenon comprises the elimination of heat (i.e., sensible and latent heat) from the food specimen to diminish its temperature to a level where liquid water transforms into ice crystals. Nowadays, versatile ranges of food products including meats, fruits, vegetables, as well as baked goods, are kept frozen assuring a prolonged shelf-life well beyond that achieved through preserving foods at refrigerated temperatures. Principally, the prolonged shelf-life of frozen food is caused by reducing the rate of deteriorative chemical and/or microbial activities to a negligible extent under low temperatures of freezing. Nonetheless, the main bottlenecks restricting the application of this outstanding preservation technique arise from either quality attributes of the foods under freezing or the energy required for the process. This chapter discusses the principal aspects of freezing, illustrates the common approaches of food freezing and their subsequent impact on physicochemical and microbial attributes of frozen food, and clarifies the postfreezing events along with providing information on the novel freezing systems in the area of the food industry.