Precautions for liquid nitrogen quick freezer

2020-08-17 10:10:01

　　Quick freezers directly enter the freezing system after the raw materials are pretreated. According to product usage and freezing equipment, freezing before packaging or freezing after packaging can be adopted. The freezing system has non-continuous (batch), semi-continuous and continuous pipeline. Commercial freezing equipments are: ①Blowing type freezers, mainly using fluidized freezers (disc or belt type) and fixed type blowing freezers; ②Metal surface contact type freezers, mainly using ultra-low temperature quick freezers for fruits; ③Liquid evaporative freezers, mainly horizontal liquid nitrogen freezers. The choice of freezing system should be based on product quality and economic considerations. The freezing system of the fruit ultra-low temperature quick-freezer has freezing speed and dry consumption.

　　Using the method of freezing before packaging, most of them use fluidized bed to realize the quick freezing of the fruit monomer, and the product obtained is loose. Under the temperature of -26～-30℃ and the product thickness is 30～40mm, the freezing time of blueberries, raspberries, strawberries and cherries only needs 4～15min. The freezing speed of liquid nitrogen freezing method is fast, and the crystallization of ice is very small. It is especially suitable for soft and tender berries. During production, the fruits are transported to the quick-freezing tunnel by the conveyor belt, and are immediately frozen after being sprayed with liquid nitrogen. For example, the freezing time of strawberry from 20°C to -18°C is only 2 minutes, and the tissue state of strawberry changes little. After 90 minutes of thawing, the amount of juice loss is 50% lower than that of blow-free monomer quick-frozen products, but the cost is higher. .

The method of freezing after packaging is suitable for: ①Frozen sugared fruits in bulk; ②Freezing soft fruits like raspberries and overripe strawberries of strawberry; ③Retail packaging frozen with syrup or sugar. The freezing system mostly uses horizontal aluminum plate freezers (if forced circulation is used, the surface temperature of the plate is -4℃, and the packaging thickness is 25mm, the freezing time is about 30min) and fixed air freezers (air temperature is usually -38~- 40℃, wind speed 4～7m/s).

Nuoruida (Tianjin) science and Technology Co., Ltd. is committed to research, development, and sales of liquid nitrogen freezer. Using European technology, we provide a variety of equipment. The main equipment is liquid nitrogen cryogenic freezer, liquid nitrogen cabinet freezer, liquid nitrogen tunnel freezer,sub-zero processing equipment, cryogenic freezing equipment, and so on.