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Why are quick freezers irreplaceable in the food industry?

2020-07-26 20:08:51



Compared with developed countries, the development of quick-frozen food in my country started very late. Although the speed of development is now fast, with an annual growth rate of more than 25%, my country's current per capita consumption of quick-frozen food is only one-tenth of that of developed countries. With the continuous growth of the income level of Chinese residents the accelerating pace of life, there is room for the development of quick-frozen food.

   With the development of the food quick-freezing industry the development of the quick-frozen food industrial production, the quick-freezer has now become an irreplaceable essential food processing equipment. So let me talk about why quick freezers are irreplaceable in the food industry.

   First, let me talk about the factors that affect quick freezing of food.

   The speed of food freezing at a thickness of 5-50 mm per hour can ensure that the number of ice crystals generated during the food freezing process is basically the same. The grains of the double spiral quick-freezer are relatively small, so as to achieve the reversibility of preservation.


Food contains two kinds of water, one is free water, its ice crystal formation stage is between 0 -5 degrees, the other is colloidal water, which is attached to the surface of food molecules. When frozen food is -18 degrees, the crystallization rate is 95% the above. In addition, storing food in a low temperature environment after ice crystallization inhibits microbial activity reproduction, achieving the purpose of long-term storage preservation (fruits vegetables inhibit respiratory heat).

   There are five main factors affecting the impact of quick freezing of food:

   1. Cooling medium temperature: The freezing speed freezing point of food are proportional to the temperature difference Δt of the cooling medium. The lower the temperature of the cooling medium, the faster the freezing speed.

2. The impact of frozen products on the wind: the wind surface area, wind speed, cold air circulation rate affect the freezing speed: experiments have shown that it takes 120 minutes for green beans to be placed under -30 degrees cooling medium at 0 wind speed, only at 4.5m/s wind speed. It takes 10 minutes.

  3. The influence of latent heat enthalpy difference: 1kg of water needs 80kcal cooling to drop 80 degrees to 0 degrees, 80kcal cooling is also required to change 0 degrees water to 0 degrees ice. The price of poultry quick-freezer shows that the latent heat of crystallization requires more cooling. Similarly, when the enthalpy difference is large, such as the high temperature of the purchase, only a large cooling capacity is required, but also a long freezing time is required.

  4. The influence of food ingredients: Foods with high thermal conductivity coefficient freeze faster than foods with low thermal conductivity coefficient. If the plastic film on the food surface only conducts heat slowly, but also hinders the wind. For example, the thermal conductivity of water is 0.604w/mk, the thermal conductivity of fat is 0.15, the thermal conductivity of plastic film is 0.028, the thermal conductivity of wind is 0.066.

   5. The influence of food thickness: the square of food thickness is proportional to the freezing time. The thicker the food, the longer the quick-freezing time.

   the factors that affect the quick freezing of food, you can know that because the quick-freezing warehouse has a large amount of food at one time, relatively high temperature food, the temperature of the cooling medium rises fluctuates, the Δt is reduced; while the quick-freezer keeps the indoor temperature almost unchanged. Because static food is placed in the quick-freezer, the unevenness of the wind is generated, the wind speed is even reduced. The static one-way blowing hinders the crystallization speed of the center of the frozen product, which is the winded part; the wind surface area of each individual in the quick-freezer tunnel Large uniform, it also accelerates freezing due to changes in wind direction. Since the food entering the quick-freezer reaches the latent heat at the same time, it is necessary to suddenly greatly increase the cold capacity to face the crystallization process, thereby generating a temperature rise extending the crystallization time. The continuous operation of the quick-freezer makes only a relatively small part of the originally limited storage capacity of the frozen product successively reach the latent heat, its cold capacity is sufficient to complete the rapid crystallization process at a stable temperature speed. It can be seen that the wholesale of poultry quick freezers pursue a fast food crystallization process to achieve reversible food preservation effects, quick freezers are essential.