Anisimova K.V., Protopopova K.A., Spiridonov A.B., Ipatova A.F., Stepanova T.O.

Development of a laboratory installation for freezing meat, fish and fruit

Freeze drying is the most advanced way of storing products. Raw materials for freeze drying should be subjected to freezing, therefore the quality of the frozen raw materials must be high. However, many products tend to lose their beneficial properties after freezing and subsequent defrosting. This is caused by the formation of large ice crystals that damage the tissue of the product. The formation of the maximum number of crystallization centers helps to save beneficial properties as much as possible and prevents the microbiological growth that cause spoilage of products. Thus, it becomes possible to increase the storage life of products and obtain a high-quality sublimated product. The product freezing process consists of three stages: cooling from +20 to 0°C, transitional phase from 0 to -5°C and freezing from -5 to -18°C. At the stage from +20 to 0°С the product is cooled down, its temperature decreases equally to the amount of heat given off. When the temperature drops from 0 to -5°C the cooled product passes from the liquid to the solid phase. The heat is removed more intensively, but the temperature is decreased slightly, and crystallization of 70% of the product fractions occurs. This is the initial stage of freezing. At the last stage the product is frozen from -5 to -18°C, which is the further final freezing.

Keywords: LABORATORY MACHINE, SELF-FREEZING, CRYOGENIC FREEZING, SHOCK FREEZING, INTENSIFICATION, ULTRASOUND