According to Miss Lin of Beijing Mayton Food Co., Ltd., which produces self-heating box meals, the self-heating of box meals is actually the result of the reaction between the water bag in the box and the heating agent packed with non-woven fabrics. Once the plastic strip is pulled open, the water bag will be broken. At this time, the heating agent will react with water, which will cause the heating agent to radiate evenly and generate heat up to 111℃. After 21 minutes, the temperature of the food reaches 55℃-61℃, and then you can eat delicious food. \x1d\ According to Mr. Deng from the Food Nutrition Expert Organizing Committee of Beijing Branch of China Medical Association, the self-heating box meal is the principle that \x1d\ generates heat energy by the chemical reaction of a heating agent, and the meal is heated through the thermal reaction, just like the principle that we heat the meal on the heater. This reaction did not touch the food, nor did it damage the nutritional components of the food. Self-heating box \x1d\ meal is a simple and convenient convenience food. \x1d\\x1d\ While pursuing convenience, the quality, hygiene and shelf life of food are also the keys to convenience food. According to Miss Lin \x1d\, the food in the lunch box is half-cooked, sterilized at a high temperature of 121℃ and packed in the lunch box. After heating for 21 minutes when eating, the food is completely hot, which will not make the food worse and ensure the original flavor. \x1d\ lunch box is made of PP five-layer composite film, which has fast heat conduction, low oxygen permeability and high freshness. \x1d\ The so-called oxygen permeability refers to measuring the degree of oxygen penetrating through the protective layer. Oxygen permeability affects the degree of preservation. It is understood that \x1d\PP five-layer composite film is a kind of edible plastic, which is non-toxic and pollution-free, and one layer of it is a composite vacuum interlayer, which can ensure good food preservation effect.