The role of various gases in modified atmosphere packaging ​

CO2 gas has the effect of inhibiting the growth and reproduction of most spoilage bacteria and molds, and is the main bacteriostatic agent in fresh-keeping gas; O2 gas can inhibit the growth and reproduction of most anaerobic spoilage bacteria, maintain the color of fresh meat, and maintain the quality of fresh fruits and vegetables. The role of respiratory metabolism in fresh state;

N2 is an inert gas, which generally does not chemically interact with food, nor is it absorbed by food. It is used as a filling gas in modified atmosphere packaging to prevent the packaging from collapsing due to the escape of CO2 and other gases from the packaging. For different foods, fruits and vegetables, the composition and proportion of the fresh-keeping gas are also different. The key to the modified atmosphere packaging of crops is to keep the oxygen permeability of the packaging material matching the respiration rate of the product.

The application of modified atmosphere packaging in food

1. Application of CO2 in food packaging A company in Sweden introduced packaging bags, containers and storage rooms filled with 100% CO2 gas to store meat. High concentration of CO2 can hinder the reproduction of microorganisms such as aerobic bacteria and mold, prolong the stagnation period and exponential growth period of microorganism growth, and play the role of anti-corrosion and anti-mold. This method enables pork to be stored for 120 days without freezing, and longer storage time if it is re-pressurized. This method has attracted great attention from meat exporting countries such as the United States and Australia. Recently, American experts adopted new technology to make plastic packaging materials with CO2. That is, using a special catalyst, CO2 and ethylene oxide (or propylene oxide) are mixed in equal amounts to make a new plastic packaging material, which is characterized by glass-like transparency and airtightness; similar to polycarbonate and polyamide Resin; it will not be completely decomposed into gas at 240°C; it has the characteristics of biodegradation and will not pollute the environment and soil.

my country has successfully used nanotechnology to catalyze CO2 synthesis of degradable plastics. That is, the catalyst used to make plastics from CO2 is "smashed" to the nanometer level to realize the polymerization of catalytic molecules and CO2, so that each gram of catalyst can catalyze about 130g of CO2, and synthesize a new packaging material containing 42% CO2. As an environmentally friendly material with excellent degradability, it has broad application prospects.

2. Application of N2 in food packaging. Nitrogen (N2) is an ideal inert gas and has special effects in food packaging: it does not react chemically with food and is not absorbed by food, can reduce the oxygen content in the packaging, and greatly inhibit the growth and reproduction of bacteria, molds and other microorganisms , slow down the oxidative deterioration and spoilage of food, so as to keep food fresh. Nitrogen-filled packaged food can also prevent the food from being squeezed and broken, the food sticking or shrinking into a ball, and maintaining the geometric shape, dryness, brittleness, color, aroma and other advantages of the food. At present, nitrogen-filled packaging is rapidly replacing traditional vacuum packaging, and has been applied to fried potato chips and fries, oil-cooked food, etc. Favored by consumers, especially children and youth, nitrogen-filled packaging is expected to be used in more food packaging.

3. Application of compound gas in packaged food. The composite modified atmosphere fresh-keeping packaging is collectively referred to as MAP packaging internationally, and the modified atmosphere fresh-keeping gas used is 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 most anaerobic spoilage bacteria; maintain the color of fresh meat, maintain the oxygen-rich respiration and freshness of fresh fruits and vegetables; N2 is used as filling gas. The composition ratio of the composite gas is properly selected according to the type of food, preservation requirements and packaging materials to achieve the effect of high preservation quality of the packaged food, good preservation of nutrients, truly achieving the original properties and delaying the shelf life of preservation. Composite modified atmosphere fresh-keeping packaging has been widely used at home and abroad.