Vacuum packaging, also known as decompression packaging, is to extract all the air in the packaging container seal, maintain the bag in a highly decompression state, air scarce is equivalent to the effect of low oxygen, so that there is no living conditions for microorganisms, in order to achieve the purpose of fresh fruit, no disease and rot.  The application of vacuum packaging in plastic bags, aluminum foil packaging, glassware, plastic and composite materials packaging, etc.  Packaging materials can be selected according to the type of article.  Because fruit is fresh food, is still in respiration, high hypoxia will cause physiological diseases, therefore, the use of vacuum packaging of fruit is less.  

Advantages of vacuum packaging:  

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

In the field of people's life and work, all kinds of plastic vacuum packaging can be found everywhere.  Lightweight, sealed, fresh, anticorrosive and rust-proof plastic vacuum packaging is widely used in many fields from food to medicine, knitwear, precision product manufacturing to metal processing plants and laboratories.  The application of plastic vacuum packaging is more and more widely, which promotes the development of plastic vacuum packaging machine, and also puts forward higher requirements for it.  

The mechanism of vacuum packaging: its purpose is to reduce the oxygen content in the packaging, prevent the mildew and decay of the packaged food, maintain the color and flavor of the food, and extend the shelf life.  

Vacuum packing is the main function of oxygen in order to prevent food spoilage, its principle is simple, because food metamorphism causing mold mainly caused by the activity of microorganism, and the survival of most microorganisms (e.g., mold and yeast) is need oxygen, and vacuum packing is using this principle, the packaging and food within the cell oxygen smoke,  So that small things lose their "living environment".  The experiment proves that when the oxygen concentration in the bag is less than or equal to 1%, the growth and reproduction rate of microorganisms decreases sharply, and when the oxygen concentration is less than or equal to 0.5%, most microorganisms will be inhibited and stop reproduction.  (Note: Vacuum packaging can not inhibit the reproduction of anaerobic bacteria and enzyme reaction caused by food spoilage and discoloration, so it needs to be combined with other auxiliary methods, such as refrigeration, quick freezing, dehydration, high temperature sterilization, irradiation sterilization, microwave sterilization, salting, etc.)  

Vacuum deaeration besides inhibiting microbial growth and reproduction, another important function is to prevent the oxidation of the food, because the oil kind food contains A lot of unsaturated fatty acid, by the effect of oxygen oxidation, sour food, deterioration, in addition, the oxidation also make vitamin A and C loss, volatile substances in food pigment by the role of oxygen, make the color darker.  Therefore, deoxygenation can effectively prevent food spoilage, maintain its color, aroma, taste and nutritional value.  

In addition to the oxygen preservation function of vacuum packing, the main function of vacuum packing is pressure resistance, gas resistance, preservation and so on, which can more effectively keep the original color, aroma, taste, shape and nutritional value of food for a long time.  In addition, many foods are not suitable for vacuum packaging and must be packed by vacuum.  Such as brittle and fragile food, easy to agaginate food, easy to deform oil food, sharp edges or higher hardness will Pierce the packaging bag of food.  After the food is packed by vacuum aeration, the aeration pressure inside the bag is greater than the atmospheric pressure outside the bag, which can effectively prevent the food from being broken and deformed under pressure and does not affect the appearance and printing decoration of the bag.  

Vacuum-filled packing is filled with nitrogen, carbon dioxide, oxygen or a mixture of two or three gases after vacuum.  Its nitrogen is inert gas, filling effect, so that the bag to maintain positive pressure, to prevent the air outside the bag into the bag, food play a protective role.  Its carbon dioxide can dissolve in all kinds of fat or water, and lead to weak acid carbonic acid, which has the activity of inhibiting fungi, corrupt bacteria and other microorganisms.  Its oxygen can inhibit the growth and reproduction of anaerobic bacteria, and maintain the freshness and color of fruits and vegetables. High concentration of oxygen can make fresh meat keep its bright red.  Fruits and vegetables are fresh but nutritious.