The reason why cans can be preserved for a long time without deterioration is completely due to the sealed container and strict sterilization, and has nothing to do with preservatives. Canned food is not mysterious. The principle of canning is also very simple: firstly heat the raw materials to kill all the microorganisms; at the same time, fully heat the packaging cans; then put the sterile food into a sterile container and heat it. Sealing; finally heat sterilization, after cooling, the volume of air inside the container's headspace shrinks, and negative pressure will be generated. The original sealed bottle will not open, and the bacteria outside will not enter. After these procedures, the food will naturally not be corrupted, and no preservatives need to be added.

     Canned food is very popular in the West. According to statistics, the annual consumption of canned Americans is about 90 kg, about 50 kg in Western Europe, 23 kg in Japan, and only 1 kg in China. Canned foods contain no preservatives and are being favored by more and more office workers because of their convenient consumption, storage resistance and diversified taste.