In cooking packaging bags, the aluminum foil used is mostly soft aluminum foil with a thickness of 7 μm. It has excellent moisture barrier, gas barrier and light barrier properties. Therefore, the composite packaging bag containing aluminum foil is fully sealed, has high fragrance retention, High oil resistance, high temperature resistance and other properties are very popular among users. So, how to choose aluminum foil when using retort bags?
1. The surface cleanliness of the aluminum foil should be high, free of oil and dust, and the surface tension should be high, which should be above 72mN/m. A simple method is to use distilled water to test. The distilled water should be fully infiltrated on the surface of the aluminum foil. 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 will occur. The phenomenon.
2. The number of pinholes in aluminum foil should be small. Aluminum foil is supposed to be the material with the best barrier properties, but if it has pinholes, its barrier properties will be greatly reduced. Gas and light will quickly penetrate directly, and the contents will quickly deteriorate. Generally speaking, the thicker the aluminum foil, the fewer the number of pinholes. For example, the number of pinholes for a 7μm thick aluminum foil should be less than 200 holes/square meter: the number of pinholes for a 9μm thick aluminum foil should be less than 100 holes/square meter. square meters. No matter how thick the aluminum foil is, the pinhole diameter should not be larger than 20 μm.
3. The texture of aluminum foil should be soft, not easy to break when folded, and should have good toughness. The purchased aluminum foil should be stored in a dry state and should not be left for too long. It should be used as soon as possible to prevent the aluminum foil from absorbing moisture and oxidizing and deteriorating.
