The Principle of Composite Modified Atmosphere Preservation Packaging Machine for Preservation

Modified atmosphere packaging, also known as MAP or CAP in foreign countries, is also known as modified atmosphere packaging or replacement gas packaging or inflatable packaging in China. Commonly used gases include N2, O2, CO2, mixed gases O2+N2 or CO2+N2+O2 (i.e. MAP). Modified atmosphere packaging technology can be widely used for the preservation of various foods, extending their shelf life, and enhancing their value.

1、 The Application of CO2 in Food Packaging

A Swedish company has launched packaging bags, containers, and storage rooms filled with CO2 gas to store meat. High concentrations of CO2 can hinder the reproduction of aerobic bacteria, molds, and other microorganisms, prolong the stagnant and exponential growth periods of microbial growth, and play a role in anti-corrosion and mold prevention. This method allows pork to be stored for 120 days without the need for freezing treatment, and if subjected to further pressure treatment, the storage time will be longer. This method has attracted great attention from meat exporting countries such as the United States and Australia.

American experts adopt new technology to make plastic packaging materials using CO2. By using a special catalyst to mix CO2 and ethylene oxide (or propylene oxide) in equal amounts, a new plastic packaging material is made, which has the characteristics of glassy transparency and airtightness; Similar to polycarbonate and polyamide resins; Will not completely decompose into gas at a temperature of 240 ℃; It has the characteristics of biodegradability and does not pollute the environment and soil.

China has successfully utilized nanotechnology to efficiently catalyze the synthesis of biodegradable plastics from CO2. The catalyst used to produce plastic from CO2 is "crushed" to the nanoscale, achieving the polymerization of catalytic molecules and CO2. Each gram of catalyst catalyzes about 130 grams of CO2, synthesizing a new packaging material containing 42% CO2. As an environmentally friendly material with excellent degradability, it has broad application prospects.

2、 The Application of Nitrogen in Food Packaging

Nitrogen (N2) is an ideal inert gas that has unique effects in food packaging: it does not react chemically with food and is not absorbed by food. It can reduce the oxygen content inside the packaging, greatly inhibit the growth and reproduction of microorganisms such as bacteria and molds, slow down the oxidation, deterioration, and decay of food, and thus keep food fresh. Nitrogen filled packaged food can also effectively prevent food from being crushed, sticking or shrinking into a lump, maintaining the geometric shape, dryness, crispness, color, aroma, and other advantages of the food. Nitrogen filled packaging is rapidly replacing traditional vacuum packaging and has been applied to fried potato chips and chips, oil cooked foods, and more. Nitrogen filled packaging is favored by consumers, especially children and young people, and is expected to be applied to more food packaging.

The application of N2 in the United States increases the strength of thin aluminum beverage cans by dissolving nitrogen in the beverage before filling it; After the beverage can is sealed, nitrogen gas is released from the beverage, creating a pressure on the wall of the can, making it equivalent to an inflatable can, thereby increasing the strength of the beverage can and achieving significant results. The canned beverage will not cause damage during transportation, stacking, or on shelves, nor will it affect the quality of the beverage. This method can also be used for beverage packaging made of polyester plastic.

When applying N2, attention must be paid to the purity and quality of N2. The purity of nitrogen separated from compressed air through membrane separation or pressure swing adsorption can reach over 99.9%. The purity of N2 used in food packaging must reach pure nitrogen level (i.e. safety level).

3、 Application of composite gases in packaged food

Composite modified atmosphere packaging is commonly referred to as MAP packaging internationally, and the modified atmosphere packaging gases used are generally composed of CO2, N2, O2, and a small amount of special gases. CO2 can inhibit the growth and reproduction of most aerobic spoilage bacteria and molds; O2 inhibits the growth and reproduction of mostly anaerobic spoilage bacteria; Maintain fresh meat color, maintain oxygen rich respiration and freshness of fresh fruits and vegetables; N2 is used as filling gas. The composite gas composition ratio is appropriately selected based on the type of food, storage requirements, and packaging materials to achieve the effect of high preservation quality of packaged food, good nutrient retention, true achievement of original properties, and delayed shelf life.