The principle of skin packaging is to place the product on a breathable bottom plate (cardboard or plastic sheet), cover it with a plastic film that is softened by heating, and vacuumize the substrate to make the film tightly wrap the product and seal with the bottom plate. . 1. The commonly used food-specific vacuum skin packaging films are as follows. Breathable film: high air permeability, easy to form on the body. Suitable for frozen food; Oxygen barrier film: high barrier to oxygen, can effectively prolong the shelf life of food; good formability, can maintain the complete shape of soft food; Multi-layer co-extruded electronic cross-linked film: good barrier properties, suitable for fresh and refrigerated food, mainly used in automatic continuous body packaging machine.