The reasons for bulging bags in meat packaging bags are as follows:Product expansion bags can be divided into physical expansion bags and bacterial expansion bags. 1Physical expansion of the bag, mainly due to the vacuum degree of the bag can not meet the requirements when vacuum sealing. In addition, during high-temperature sterilization, since the pressure in the bag is greater than the pressure in the pot, it is necessary to add back pressure for sterilization. Improper control of the back pressure can easily cause physical swelling of the bag. 2, Bacterial swelling bag is due to incomplete sterilization and the reproduction of gas-producing bacteria in the product.