Rekomendatsii Mezhdunarodnogo instituta kholoda po proizvodstvu i khraneniyu zamorozhennykh pishchevykh produktov

Scientific aspects of freezing, storage and thawing foodstuffs are examined. Thermophysical aspects of freezing include such notions as an initial point of freezing (a cryoscopic temperature of ice formation beginning); ice crystallization that is a period of appearance of first ice crystals before their precipitation in the solution. The crystallization period is characterized by the initiation of crystallization centers, crystals growth accompanied by water diffusion. The ice content in frozen substances is a function of the temperature and the initial concentration of dissolved substances in them. As a rule at temperatures lower -40 оС the change of ice quantity in frozen products is not observed. The storage of frozen products may be accompanied by the crystals size growth that is called a secondary crystallization leading to water diffusion into the intercellular space and as a result to increasing the speed of destruction and intensive exudation at defrosting. To prevent the secondary crystallization the cryoprotectors are introduced in the product. At freezing the change of the volume and mass (loss of weight) of the product takes place as well as its thermal properties are modified (heat conductivity and specific thermal capacity). Keywords: thermophysical aspects of freezing, cryoscopic temperature, ice crystallization, secondary crystallization, cryoprotectors, loss of weight.

теплофизические аспекты замораживания, криоскопическая температура, кристаллизация льда, вторичная кристаллизация, криопротекторы, усушка