(1) understand the characteristics of the mask itself and determine the required protection conditions.
First, we should understand the main components, characteristics of the mask, and the internal reactions that may occur during processing, storage and transportation, including the internal biochemical reaction of abiotic and the mechanism of biological spoilage reaction. Second, we should study the sensitive factors that affect the main components of food, especially fat, protein, vitamins and other nutrients, including light and oxygen. Gas, temperature, microorganism, physics, mechanical mechanics and other factors. Only by grasping the biological factors of packaged foods and determining the protective requirements of the mask bags can we correctly select the packaging materials and packaging processes.
（2） Study and master the packaging performance, application scope and conditions of packaging materials
There are various kinds of bags and different properties. Therefore, only by knowing the packaging properties of various packaging materials and containers can we choose the packaging materials that can protect the flavor and quality of food and reflect the value of its products and make the packaging cost reasonable. For example, low temperature resistant food packaging materials should be selected.