Modified atmosphere fresh-keeping packaging is also called MAP or CAP in foreign countries, modified atmosphere packaging or replacement gas packaging and inflatable packaging in China. It uses packaging materials with gas barrier properties to package food. According to the actual needs of customers, a certain proportion of oxygen + carbon dioxide + nitrogen, nitrogen + carbon dioxide, oxygen + carbon dioxide mixed gas is filled into the package to prevent food from physical, chemical, biological and other aspects. Slow down the speed of quality decline, thereby extending the shelf life of food and enhancing the value of food.