ABSTRACT
Freezing is one of the most important food refrigeration processes for long-term preservation and is applied to reduce the temperature of all parts of the food product below the freezing point. Food freezing based on scientific techniques was introduced in the early 1900s and the first packs of frozen foods were produced in the United States in 1918. The quantity of heat to be extracted from the food products to be frozen may be approximately derived by multiplying the latent heat of freezing water by the water content of the food product. Enzymatic reactions are chemical, biochemical, and physical reactions. They influence the product quality during the processes before and/or after freezing, not during the freezing process. Spoilage of food products is caused chiefly by microorganisms. Since growth of microorganisms is dependent on the temperature, lowering the temperature is of great importance for food preservation. Packaging materials must provide several functions other than merely containing the food products.
