Yogurt is a kind of dairy product made of fresh milk, sterilized, added with beneficial bacteria (starter), fermented, cooled and filled. There are many beneficial bacteria in yogurt, which has a good effect on establishing a normal intestinal flora environment and helping digestion. However, yogurt and fresh milk cannot be completely equated. Yogurt needs to be refrigerated, its shelf life is short, it can't be heated, and it is not suitable for drinking on an empty stomach. Although yogurt contains all the nutrients of fresh milk in theory, it is still limited by many conditions such as processing technology, technology and hygiene.