Vacuum Pump System in Vacuum Packaging
Vacuum packaging is a kind of packaging method, in which articles are packed into airtight containers and vacuum pumps are used before sealing, so that there is no air in the sealed containers at all. Vacuum packaging is also called decompression packaging or exhaust packaging. This kind of packaging can prevent the moisture from entering the packaging container, and also avoid the moisture in the sealed moisture-proof packaging and dew when the temperature drops. Vacuum packaging should be used to prevent excessive vacuum.
Common grains and processed goods can be packed in vacuum. Vacuum packaging can not only prevent or reduce the oxidation, discoloration and taste of grains, but also inhibit the growth of some fungi and bacteria.
At present, the processing and preservation of grain and oil are still in a low-level and extensive state, and the refrigeration conditions in China can not compare with those in the United States, Japan and other prosperous countries, thus resulting in a large loss of agricultural products and resource wastage. Vacuum packaging can maintain the quality and nutritional components of grain and agricultural products, which has attracted much attention of the grain industry.
In addition to controlling external temperature and sterility, vacuum packaging is more important to control the suitable gas environment of grain to achieve the desired fresh-keeping purpose. The main methods are mechanical extrusion type and suction tube degassing type. Either way, the air in the bag should be pumped out and then sealed. Its main characteristics are: reducing oxygen content in bags, inhibiting the growth and development of fungi and bacteria, controlling grain metamorphosis, and achieving the purpose of preservation and quality. In addition, after vacuum packaging, it can also resist mechanical pressure and reduce vibration, which is conducive to long-distance transportation and sales.
The mechanism of vacuum packaging: Its purpose is to reduce the oxygen content in packaging, avoid the mildew degeneration of packaged food, hold the color and fragrance of food, and extend the shelf life.
The main function of vacuum packaging is to remove oxygen in order to avoid food metamorphosis. Its principle is also simple. Because food mouldy metamorphosis is mainly formed by the activity of microorganisms, and the survival of most microorganisms (such as molds and yeasts) needs oxygen. Vacuum packaging uses this principle to extract oxygen from packaging bags and food cells so as to make microorganisms lose.“ The living environment. It has been proved that when the oxygen concentration in the packaging bag is less than 1%, the growth and reproduction speed of microorganisms will drop sharply. When the oxygen concentration is less than 0.5%, most microorganisms will be inhibited and stopped. (Note: Vacuum packaging can not inhibit the anaerobic bacteria multiplication and food degradation and discoloration caused by enzymatic reaction, so it needs to be separated from other auxiliary methods, such as refrigeration, quick freezing, dehydration, high temperature sterilization, irradiation sterilization, microwave sterilization, salting, etc.).
In addition to inhibiting the growth and reproduction of microorganisms, the other important function of vacuum oxygen is to avoid food oxidation. Because of the large amount of unsaturated fatty acids in oily food, it oxidizes and changes the taste and metamorphosis of food. In addition, oxidation also causes the loss of vitamin A and C, and the effect of oxygen on the unstable substances in food pigments makes the color darker. Therefore, deoxygenation can effectively avoid food metamorphosis, adhere to its color, aroma, taste and nutritional value.
The main function of vacuum air-filled packaging is not only the function of oxygen and quality preservation, but also the function of pressure resistance, gas resistance and freshness preservation. It can make food stick to its original color, aroma, taste, shape and nutritional value for a long time. In addition, there are many foods that are not suitable for vacuum packaging and must be packed with vacuum inflation. For example, crunchy and fragile food, caking food, deformable and oily food, food with sharp edges and corners or higher hardness will puncture the packaging bags, etc. After food is packed by vacuum aeration, the air pressure inside the bag is stronger than that outside the bag. It can effectively avoid food crushing and deformation without affecting the appearance of the bag and printing decoration.
Vacuum inflatable packaging is filled with nitrogen, carbon dioxide, oxygen single gas or a mixture of two or three gases after vacuum. Nitrogen is inert gas, which fills the bag and keeps positive pressure inside, so as to avoid air outside the bag entering the bag and play a maintenance role for food. Its carbon dioxide can dissolve in various kinds of fat or water, lead to weak acidity of carbonate, has the activity of inhibiting microorganisms such as fungi, erosive bacteria and so on. Its oxygen can inhibit the growth and reproduction of anaerobic bacteria, adhere to the novelty and color of fruits and vegetables, and high concentration of oxygen can make new meat stick to its bright red.