Vacuum packaging can protect products from environmental pollution, extend the shelf life of food and improve the value and quality of products. Vacuum packaging technology originated in the 1940s. Since 1950, polyester and polyethylene plastic films were successfully applied to commodity packaging, vacuum packaging machines have developed rapidly.

In people's life and work fields, all kinds of plastic vacuum packaging abound. Portable, sealed, fresh-keeping, anticorrosive and antirust plastic vacuum packaging covers many fields, from food to medicines and knitwear, from precision product manufacturing to metal processing plants and laboratories. The increasingly extensive application of plastic vacuum packaging promotes the development of plastic vacuum packaging machine, and puts forward higher requirements for it.

Mechanism of vacuum packaging: Its purpose is to reduce the oxygen content in the package, prevent the packaged food from mildew and deterioration, maintain the color and flavor of the food, and extend the shelf life.

The main function of vacuum packaging is to remove oxygen, thus preventing food from spoilage. Its principle is also relatively simple, because food mildew and corruption are mainly caused by microbial activities, and most microorganisms (such as mold and yeast) need oxygen to survive. Vacuum packaging is to use this principle to pump oxygen out of packaging bags and food cells, so that tiny objects lose their "living environment". Experiments show that when the oxygen concentration in the packaging bag is ≤ 65438 0%, the growth and reproduction speed of microorganisms will drop sharply, and when the oxygen concentration is ≤0.5%, most microorganisms will be inhibited and stop reproducing. (Note: Vacuum packaging can't inhibit food deterioration and discoloration caused by anaerobic bacteria reproduction and enzyme reaction, and it needs to be combined with other auxiliary methods, such as cold storage, quick freezing, dehydration, high-temperature sterilization, irradiation sterilization, microwave sterilization, salt curing, etc. )

In addition to inhibiting the growth and reproduction of microorganisms, vacuum deoxygenation also plays an important role in preventing food oxidation. Because there are a lot of unsaturated fatty acids in oil-based foods, they are oxidized by oxygen, which makes the food go bad. In addition, oxidation also causes the loss of vitamins A and C, and the unstable substances in food pigments are blackened by oxygen. Therefore, deoxidation can effectively prevent food from deteriorating and maintain its color, aroma, taste and nutritional value.

The main function of vacuum inflatable packaging is not only the function of oxygen removal and quality preservation, but also the function of pressure resistance, gas resistance and freshness preservation, which can effectively maintain the original color, fragrance, taste, shape and nutritional value of food for a long time. In addition, many foods are not suitable for vacuum packaging, so they must be packed by vacuum inflation. Such as fragile food, easy to agglomerate food, easy to deform and greasy food, food with sharp edges or hardness that will puncture the packaging bag, etc. After the food is inflated in vacuum, the inflation pressure in the packaging bag is greater than the atmospheric pressure outside the packaging bag, which can effectively prevent the food from being extruded and deformed without affecting the appearance, printing and decoration of the packaging bag.

Inflatable packaging is filled with nitrogen, carbon dioxide and oxygen or a mixture of two or three gases after vacuum pumping. Its nitrogen gas is an inert gas, which plays the role of filling and keeps the bag at positive pressure, thus preventing the air outside the bag from entering the bag and protecting the food. Its carbon dioxide can be dissolved in various fats or water to generate weakly acidic carbonic acid, which has the activity of inhibiting microorganisms such as mold and spoilage bacteria. Its oxygen can inhibit the growth and reproduction of anaerobic bacteria, keep the freshness and color of fruits and vegetables, and the high concentration of oxygen can keep fresh meat bright red. Fruits and vegetables are fresh, but the nutrients will not be lost.