When making high temperature retort bags, you must first choose the aluminum foil used in the retort packaging bags, and pay attention to three points: The surface cleanliness of the aluminum foil should be high, there should be no oil stains and dust, and the surface tension should be high, which should reach more than 72mN/m. A simple method is to test with distilled water, which should be fully wetted on the surface of the high-temperature cooking bag. If the surface of the aluminum foil is seriously oily, it will affect the composite fastness of the aluminum foil and other materials, especially after the packaging bag is cooked at high temperature, delamination and peeling will occur. Aluminum foil has fewer pinholes. Aluminum foil should be a barrier material, but if it has pinholes, its barrier properties will be greatly reduced, gas and light will penetrate quickly and directly, and the contents will soon deteriorate. The texture of the aluminum foil should be soft, it should not be easy to break when folded, and it should have good toughness. The purchased aluminum foil should be stored in a dry state, and should not be stored for too long. It should be used as soon as possible to prevent the aluminum foil from absorbing moisture and oxidizing and deteriorating.