Vacuum-packaged food can generally be stored for 1 to 12 months. The storage time varies depending on various factors such as the type of food and the processing before packaging. The basic principle of refrigeration in vacuum packaging bags is usually to remove oxygen, inhibit the growth and reproduction of microorganisms, and prevent oxidation of food materials.
Vacuum-packaged food can be stored for 1 to 12 months. The storage time of vacuum-packaged food varies depending on various factors such as the type of food and the processing before outer packaging. The basic principle of preserving food in vacuum packaging bags is usually to remove O2. Food spoilage is caused by the growth and reproduction of microorganisms and germs.
Most microorganisms such as Aspergillus flavus and yeast require oxygen to survive. Vacuum-packaged food removes O2 from the outer packaging, which may inhibit the growth and reproduction rate of microorganisms. The unsaturated fats contained in fatty foods are easily oxidized and spoiled. After the vacuum removes oxygen, the oxidation of the food is also prevented.
Food that is easily broken and easily deformed is filled with carbon dioxide, N2 and other mixed gases after deoxygenating the vacuum pump. It can play a filling role, making the pressure of the air inside and outside the bag exceed the pressure of the air outside the bag, which not only prevents the air outside the bag from entering the bag, but also prevents the food from being damaged and deformed.
Common ways of preserving food are:
1. The most common application of ultra-low temperature preservation is refrigerator preservation. Ultralow temperature can reduce or stop the growth rate of microorganisms in food and slow down the speed of all chemical reactions in food, but it cannot eliminate microorganisms. When food is stored below 10℃, the effect of microorganisms on food must be greatly reduced. The effect of microorganisms on food below 0℃ must be greatly reduced. Decomposition essentially ceases. However, in low-temperature environments, the fat in food still cannot prevent deterioration. The lipolytic enzyme that breaks down fat will only cease activity when it falls below -20°C. Therefore, the refrigerators used by ordinary people to store food are not safes.
Common ultra-low temperature storage methods include 0℃~4℃ and -18~35℃. Fish and dairy products are easy to deteriorate due to their own cofactors or microorganisms, and must be stored at -18 Store frozen at ℃～-35℃. Fresh fruits and vegetables still have metabolic vitality and natural resistance, and can be refrigerated and stored at 0°C to 4°C. Before food is refrigerated, try to maintain freshness as much as possible, reduce environmental pollution, and increase the shelf life. The quality of food that has been refrigerated for a long period of time should be regularly maintained, and attention should be paid to whether there are any signs of fatty acid spoilage, especially if the fat of fish and meat turns yellow, they should be handled properly.
2. Continuous high-temperature storage and cooking can kill most microorganisms in food and destroy antioxidants in food, preventing food from being easily contaminated by microorganisms if it is not stored properly. Therefore, after cooking, , be sure to cook it thoroughly every other meal overnight (especially in summer) to kill microorganisms that will cause further contamination, otherwise accidents are prone to occur.
3. When the moisture content in dehydrated and preserved food drops to a certain level, microorganisms cannot breed and enzyme activity is inhibited, thus preventing food from spoiling. Generally, the food moisture content that prevents microorganisms from growing and breeding is less than 13% to 16% for Aspergillus flavus; less than 18% for bacteria; and less than 20% for yeast. Common dehydration and preservation methods include: air drying, air drying, heating and scalding, dry hot air evaporation, reduced pressure evaporation and freeze drying, etc. There are two common types of drying and air-drying at home. Before the rainy weather arrives, nuts such as jujubes are dried in the sun and then placed in a drying container. The sealing properties can increase the storage time.
4. When the edible salt content of food soaked in salt water reaches 8% to 10%, most microorganisms will stop breeding, but they cannot be killed. The content of salt to kill microorganisms is as high as 15%, and it needs to be marinated for several days. Strictly speaking, salt water soaking is just an antibacterial method.
5. After adding a large amount of sugar to candied food, it forms an antibacterial permeability and has a certain anti-corrosion effect, but the sugar concentration must be 60% to 65% to have anti-corrosion effect. Because candied foods easily absorb moisture in the air; therefore, candied foods are still prone to spoilage after being stored without sealing.