Vacuum bags, also known as decompression packaging, are based on the principle of atmospheric pressure. The main function of vacuum bags is to deoxygenate, which is beneficial to prevent food from mildew and deterioration. Vacuum packaging is a process in which the oxygen in the packaging bag and in the food cells is extracted by an air extractor, so that the microorganisms lose their "living environment". The vacuum bag can also prevent the oxidation of food, so that the food does not taste, and reduces the loss of vitamins A and C.
Vacuum packaging materials are usually three-sealed packaging bags made of double-layer composite films or three-layer aluminum thin composite films. Two types of vacuum packaging machines are commonly used: cavity type and external pumping type. my country's vacuum packaging technology was developed in the early 1980s, and the vacuum inflatable packaging technology began to be used in the early 1990s.
The vacuum inflatable packaging is filled with nitrogen, carbon dioxide and other gases after the vacuum is drawn. Nitrogen is an inert gas, which acts as a filling and keeps the vacuum bag at a positive pressure to prevent the air outside the bag from entering the bag, and has a protective effect on the food. Carbon dioxide has the activity of inhibiting microorganisms such as mold and spoilage bacteria. Some foods such as crispy and fragile food, easily deformed and oily food, food with sharp edges and corners or high hardness will puncture the vacuum bag, etc. After vacuum inflatable packaging, the inflation pressure in the vacuum bag is stronger than the atmospheric pressure outside the packaging bag, which can effectively Prevent the food from being crushed and deformed under pressure, and does not affect the appearance and printing decoration of the packaging bag. With the promotion of vacuum bag small packaging and the development of supermarkets, its scope of application will become more and more extensive, and some will gradually replace hard packaging.
In addition to inhibiting the growth and reproduction of microorganisms, vacuum deoxygenation has another important function to prevent food oxidation. Because oily food contains a lot of unsaturated fatty acids, it is oxidized by the action of oxygen, which makes the food taste bad and spoiled. In addition, oxidation also causes the loss of vitamin A and vitamin C, and the unstable substances in food coloring are affected by oxygen to darken the color. Therefore, deoxygenation can effectively prevent food spoilage and maintain its color, aroma, taste and nutritional value.
