First, vacuum packaging: vacuum packaging is to put food into a special packaging container, use a vacuum pump to remove the gas from the container, and then package it. After the gas in the container is evacuated, a vacuum environment is formed. It is characterized by low oxygen content and low water vapor content, which can prevent food from oxidation, mildew and corruption, reduce discoloration and fading, reduce the loss of vitamins A and C, and prevent the color, fragrance and taste of food from changing. Second, the main function of vacuum packaging is to ensure the shelf life of food. The specific function is as follows: 1. Prevent dryness. Packaging materials block water vapor, prevent drying and keep the surface of fresh meat soft; 2. Prevent oxidation. When vacuumizing, oxygen and air are excluded together, and the packaging material is isolated from the atmosphere, so that oxygen cannot enter the packaging bag and is completely blocked; 3. Prevent the growth of microorganisms. Bacteria, yeast, etc. It seriously affects the quality of food, and its metabolites have toxic and side effects on human body, which makes food corrupt. Vacuum-packed products can prevent microbial secondary pollution and the survival of aerobic microorganisms. 4. Prevent fragrance loss. Packaging materials can effectively block the escape of volatile aromatic substances, and can also prevent crosstalk between different products; 5. Avoid freezing damage. Packaging materials isolate products from the outside world, so the formation and air drying of ice during freezing can minimize losses; 6. prevent being touched. So that the product can meet the hygiene requirements of buyers. 3. Vacuum packaging is mainly used for the following products: 1. Pickled products: sausage, ham, bacon, salted duck, etc. 2. Pickled vegetables: pickled vegetables, dried radishes, pickles, etc. ; 3. Bean products: dried bean curd, vegetarian chicken, bean paste, etc. 4. Convenience food: rice, cooked vegetables, etc. 5. Cooked food products: roast chicken, roast duck, beef sauce, etc.