Vacuum packaging protects products from environmental pollution and prolongs the shelf life of food, which can improve the value and quality of products. Since the successful application of polyester and polyethylene plastic films to commodity packaging in 1950, vacuum packaging machines have developed rapidly.
In our daily life, all kinds of plastic vacuum packaging abound. Lightweight, sealed, fresh-keeping, anti-corrosion, and anti-rust plastic vacuum packaging covers many fields from food to medicine, knitwear, from precision product manufacturing to metal processing plants and laboratories. The increasing application of plastic vacuum packaging has promoted the development of plastic vacuum packaging machines and put forward higher requirements for them.
The mechanism of vacuum packaging
Its purpose is to reduce the oxygen content in the package, prevent the mildew and deterioration of the packaged food, maintain the color and fragrance of the food, and extend the shelf life.
The main function of vacuum packaging
The main function of vacuum packaging is to remove oxygen in order to help prevent food from spoiling. The principle is also relatively simple. The mildew and spoilage of food is mainly caused by the activities of microorganisms, and most of the microorganisms need oxygen to survive, The vacuum packaging removes the oxygen in the packaging bag , so that the micro-objects lose the "survival environment".
In addition to inhibiting the growth and reproduction of microorganisms, vacuum deoxygenation has another important function which is to prevent food oxidation. Because fats and oils contain a large amount of unsaturated fatty acids, they are oxidized under the action of oxygen, which makes the food taste and deteriorate.
In addition, oxidation also causes the loss of vitamins A and C, and the unstable substances in food pigments are affected by oxygen to darken the color. Therefore, deoxygenation can effectively prevent food from spoiling and maintain its color, aroma, taste and nutritional value.
In addition to the oxygen-removing and quality-preserving functions of vacuum packaging, vacuum is also of compression resistance, gas barrier, and freshness preservation, which can more effectively maintain the original color, aroma, taste, shape of food for a long time.
However,just vacuum is not enough for some special foods, as also they also needs to be filled with gas after vacuum. These special food includes crunchy and fragile foods, foods that are easy to agglomerate, foods that are easy to deform and run out of oil, foods with sharp edges or corners or high hardness that will pierce the packaging bag.
After vacuum and gas flush, the pressure inside the package is strong than outside, which can effectively prevent the food from being crushed and deformed under pressure without affecting the appearance of the packaging bag.
The vacuum inflatable package is filled with a single gas of nitrogen, carbon dioxide, oxygen or a mixture of two or three gases after being vacuumed.
The nitrogen is an inert gas, which plays a filling role and keeps positive pressure inside the bag to prevent the air outside the bag from entering the bag and protect the food.
The carbon dioxide can be dissolved in various fats or water to form weakly acidic carbonic acid , which helps to inhibit the reproduction of microorganisms.
The oxygen can inhibit the growth and reproduction of anaerobic bacteria, and keep the freshness and color of fruits and vegetables. The high concentration of oxygen can keep fresh meats bright red. The freshness of fruits and vegetables does not lose their nutrition.
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