Frozen food packaging bags are special-purpose packaging containers. In order to improve the freshness and shelf life of the product, it is necessary to use freezing or refrigeration to greatly limit the growth and reproduction of microorganisms and reduce the rate of food spoilage. According to the type of food and storage temperature, our performance requirements for product packaging are also different. At the same time, we also need to consider the nutritional content and taste of food when storing food. Compound packaging bags, aluminum foil bags, and plastic packaging bags all have a suitable storage temperature for different products, such as 1. Tea leaves are stored at a temperature of minus 20 degrees to 10 degrees, which can prevent the quality from deteriorating for a long time and keep vitamins from being damaged. 2. The best temperature for miscellaneous grains: 8 degrees to 15 degrees, which can prevent the food from worms. 3. The best temperature for frozen fish: it is below minus 3 degrees, at this temperature the fish is not easy to deteriorate, and its freshness can be preserved. In addition, there are two common problems with frozen food: 1. Dry consumption and freezing The air pressure in the refrigerator will cause a difference between the water vapor of the food and the air in the refrigerator as the temperature changes, and there are The sublimation of ice crystals causes the surface to dry out and lose its mass. This is the phenomenon of “dry consumption”. A peculiar form in which frozen meat appears qualitatively during storage is called “frozen burning”. It is characterized by dryness or dry spots on the entire surface of frozen meat. Frozen burning is the result of fatty oxidation rancidity and carbonyl ammonia reaction of frozen food during frozen storage. It not only makes the food produce a hara-flavored taste, but also has a yellow-brown change, and the sensory, flavor and nutritional value are deteriorated. 2. In the freezing environment, the material properties of the packaging bags gradually decline. The main material of the frozen food packaging bags is plastic. The plastic will be brittle and rupture easily in a low temperature environment for a long time, and the physical properties will drop sharply, which reflects the poor cold resistance of plastic materials. weakness. In general, the cold resistance of plastics is expressed by the embrittlement temperature. As the temperature decreases, the plastic becomes brittle and easy to break due to the decrease in the mobility of its polymer molecular chain. Under the specified impact strength, 50% of the plastic is brittle failure, and the temperature at this time is the embrittlement temperature. , that is, the lower temperature limit for the normal use of plastic materials. If the packaging materials used for frozen food have poor cold resistance, the sharp protrusions of the frozen food can easily pierce the packaging during the later transportation and loading process, causing leakage problems and accelerating the spoilage of the food. Solution To minimize the frequency of the above two problems and ensure the safety of frozen food, we can start from the following aspects. 1. Choose high-barrier, high-strength inner packaging materials There are many kinds of packaging materials and different properties. Only by understanding the physical properties of various packaging materials, you can choose reasonable materials according to the protection requirements of frozen food, so that not only It can maintain the flavor and quality of food, and can also reflect the value of commodities. At present, the plastic flexible packaging used in the field of frozen food is mainly divided into three categories: the first category is single-layer packaging bags, such as PE bags, which have a relatively poor barrier effect and are generally used for vegetable packaging; the second category is composite flexible plastic packaging Bags, which use adhesives to bond two or more layers of plastic film materials together, such as OPP/LLDPE, NY/LLDPE, etc., have relatively good moisture resistance, cold resistance and puncture resistance; Extruded soft plastic packaging bags, which melt and extrude raw materials with different functions such as PA, PE, PP, PET, EVOH, etc. in turn, and then compound them together after inflation molding and cooling. Pollution, high barrier, high strength, high and low temperature resistance, etc.
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