Application of carbon dioxide and nitrogen in food packaging
Modified atmosphere packaging is also called MAP or CAP abroad, and domestically, it is called modified atmosphere packaging or replacement gas packaging and inflatable packaging. Commonly used gases are N2, O2, CO2, mixed gas O2+N2 or CO2+N2+O2 (that is, MAP). Modified atmosphere packaging technology can be widely used to preserve the freshness of all kinds of food, extend the shelf life of food, and enhance the value of food.
1. The application of CO2 in food packaging
A Swedish company introduced packaging bags, containers, and storage rooms filled with 100% CO2 to store meat. The high concentration of CO2 can hinder the reproduction of aerobic bacteria, molds and other microorganisms, prolong the stagnation period and exponential growth period of microbial growth, and play a role of antiseptic and antifungal. This method enables pork to be stored for 120 days without freezing treatment. If it is pressurized again, the storage time is longer. This method has attracted great attention from meat exporting countries such as the United States and Australia.
American experts adopt new technology and use CO2 to make plastic packaging materials. Even if a special catalyst is used, 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 air-impermeability; similar to polycarbonate and polyamide Resin; it will not completely decompose into gas at 240℃; it has the characteristics of biological decomposition and will not pollute the environment and soil.
2. The application of nitrogen in food packaging
Nitrogen (N2) is an ideal inert gas. It has special effects in food packaging: it does not chemically react with food and is not absorbed by food. It can reduce the oxygen content in the package and greatly inhibit the growth and reproduction of bacteria, molds and other microorganisms. , To slow down the oxidative deterioration and decay of food, so as to keep the food fresh. Nitrogen-filled packaged food can also prevent the food from crushing, sticking or shrinking, maintaining the geometric shape, dryness, crispness, color, and flavor of the food. Nitrogen-filled packaging is rapidly replacing traditional vacuum packaging and has been applied to fried potato chips and French fries, oil-cooked foods, etc. Favored by consumers, especially children and young people, nitrogen-filled packaging is expected to be used in more food packaging.
When applying N2, we must pay attention to the purity and quality of N2. The purity of nitrogen separated from compressed air by membrane separation or pressure swing adsorption can reach over 99.9%. The purity of N2 used in food packaging must reach the pure nitrogen level (i.e. safety level).
3. Application of compound gas in packaged food
Composite modified atmosphere packaging is collectively referred to as MAP packaging internationally, and the modified atmosphere preservation 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 can inhibit the growth and reproduction of most anaerobic spoilage bacteria; maintain the color of fresh meat, maintain oxygen-rich respiration and freshness of fresh fruits and vegetables; N2 is used as gas filling. The compound gas composition ratio is appropriately selected according to the type of food, preservation requirements and packaging materials to achieve high-quality preservation of packaged food, maintain good nutrients, and can truly achieve the effect of original properties and delay the shelf life of preservation.
Compound modified atmosphere packaging has been widely used at home and abroad.
