Nowadays, the canning industry has made great progress and progress, and the extension and connotation of canned foods are constantly expanding and improving. According to the definition of Zhang Xueyuan, a famous food expert in China and the former Ministry of Light Industry, canned food is a kind of food that is sealed and sterilized, meets commercial sterility requirements, and does not need or allow any preservatives. Therefore, it should be further clarified that if the food is sealed and sterilized or sterilized (ie aseptic packaging) to achieve commercial sterility, long-term preservation at room temperature should be regarded as canned food, and must not be limited to traditional artificial canned food. Inside. With the expansion of packaging materials and forms, in addition to tinplate cans, glass jars, aluminum alloy cans, other soft cans and aseptic bulk packaging made of aluminum-plastic composite packaging materials; first sterilized and repackaged The Tetra Pak is like a variety of juices, vegetable juices, jellies, sauces, protein drinks, etc.; heat-sterilizable plastic cans, various sausages made of plastic casings should be regarded as canned food.
The earliest and most used tinplate cans are coated with a layer of enamel to protect the iron sheet from any effect on food. In addition, it is cheap, strong, easy to form, and beautiful in appearance. Very successful as a container for canned food. There are two-piece aluminum cans, and the can opening method has evolved to open the cans without special tools, but the cans are not as diverse as tinplate cans, and because of the higher cost, the use is still not as popular as tinplate.