Principle And Technical Knowledge Of Refrigerated Food In Supermarket Refrigerator

Food cold storage, also known as low-temperature storage, refers to a method of storing food at a low temperature of 0°C or slightly higher than the freezing point of the food. Supermarket refrigeration prevents the spoilage of food and maintains the freshness and nutritional value of food by inhibiting the activities of microorganisms and enzymes and reducing the activity in the food matrix. Supermarket freezer is currently the most commonly used food storage method with better results, lower prices, and freshness-keeping time.

The principle of food refrigeration.

Food spoilage is mainly caused by the biological activities of microorganisms and the biochemical reactions carried out by enzymes in the food. Animal foods, such as poultry, livestock, fish, etc., are easily contaminated by bacteria during storage, and bacteria multiply quickly, causing food corruption. However, the reproduction of microorganisms and the exertion of enzyme activities require appropriate temperature and moisture conditions; if the environment is not suitable, the microorganisms will stop reproducing or even die, and the enzymes will lose their catalytic ability or even be destroyed. Putting animal food under low temperature conditions can inhibit the reproduction of microorganisms and the effect of enzymes on the food, and can be stored for a long time without spoilage.

For plant foods, the cause of spoilage is respiration. Although fruits and vegetables cannot continue to grow after being picked, they are still an organism with life and respiration. Low temperature can weaken the respiration of fruit and vegetable foods and extend their shelf life. But the temperature should not be too low, otherwise it will cause physiological diseases of plant foods and even freeze to death. Therefore, the refrigeration temperature of plant food should be close to its freezing point without causing plants to freeze to death.

 Requirements for the construction of cold storage.

1. The thermal insulation performance of the thermal insulation layer is better. The better the thermal insulation performance of the thermal insulation layer, the smaller the cold consumption, the smaller the temperature fluctuation caused by the storage, which is conducive to the maintenance of the quality of the storage, prolongs the storage time, reduces the shrinkage loss of the storage, and can Save investment and operating costs of refrigeration equipment.

2. Pay attention to the moisture-proof on the outside of the insulation layer. The temperature on both sides of the cold storage enclosure is inconsistent, and it is easy to form a water vapor partial pressure difference. With the transfer of heat, the water vapor outside the storage will penetrate into the storage, so a moisture-proof and gas barrier should be provided. There are three common methods of moisture-proof: asphalt moisture-proof, plastic film moisture-proof, and the use of metal sandwich panels as a moisture-proof layer.

3. A well-installed air extraction system. After food is stored in the cold storage for a certain period of time, gaseous substances such as carbon dioxide and ethylene are likely to accumulate. Therefore, a good air extraction system must be installed so that fresh air can be changed frequently to facilitate the storage and preservation of food.

4. Choose a suitable refrigeration system. The cold storage is obtained by artificial refrigeration. At present, liquid vaporization refrigeration method or vapor refrigeration method are commonly used. Vapor refrigeration methods can be divided into three types of refrigeration methods: compression, absorption, and ejection, among which compression is the most widely used. The compression refrigerator is mainly composed of a compressor, a condenser, a regulating valve and an evaporator. It is a closed cycle system.

Some problems should be paid attention to when refrigerating.

1. Pre-cooling. Pre-cooling is a pre-cooling method for food before long-distance transportation or refrigeration. The requirement is to quickly reduce the food to be stored to a specified temperature. It is an important measure to maintain the quality of the food being transported and extend the storage life. Pre-cooling is usually carried out in cold storage and pre-cooling room. Commonly used pre-cooling methods include natural air cooling, ventilation cooling, vacuum cooling and cold water cooling. The pre-cooled food should be quickly placed in a low temperature environment for storage.

2. The allowable temperature range and shelf life. The temperature in the cold storage is not likely to be constant at a certain temperature value, and the storage temperature will fluctuate within a certain range due to factors such as the performance of the refrigerator, the size of the storage capacity, and the temperature difference between inside and outside. Generally speaking, the storage temperature of food is lower, and the smaller the range of change, the better. This is conducive to food preservation, to prevent loss and low temperature physiological diseases.

 3. Temperature control. Different foods have different optimum refrigeration temperatures. The temperature of the cold storage and the temperature of the food after storage are affected by many factors, such as the difference between the temperature of the food and the storage temperature when entering the storage, the performance and storage capacity of the refrigerator, the air circulation in the storage, the stacking method, the variety and maturity of the food Degree and so on. Stacking should be reasonable when entering the warehouse, and the temperature of the warehouse should be adjusted according to the actual situation; a gradual heating method should be adopted before leaving the warehouse to avoid condensation on the surface of the food due to the large temperature difference between inside and outside.

4. Humidity control. The cold storage often absorbs a large amount of heat from the evaporator and continuously accumulates frost on it, and continuously melts the frost away, resulting in the humidity in the storage being often lower than the humidity requirement for food storage. You can increase the area of the evaporator, reduce frosting, and install spray equipment or automatic humidifiers to adjust the humidity in the cold storage. In addition, when the relative humidity in the warehouse increases due to frequent entry and exit of goods, a moisture absorber can be installed to absorb moisture, and the management of cold storage can be strengthened to strictly control the frequent entry and exit of goods and personnel.

Sanye is a 15 year old brand of commercial refrigeration equipment in China. If you have any questions, you are welcome to consult. At the same time, you are also welcome to order products.https://www.freezer-china.com/