Kefir (English: Kefir) is a kind of fermented milk, which originated in the Caucasus and has the longest life in the world. It is different from ordinary yogurt because it is fermented by 10 kinds of lactic acid bacteria and yeast.

Milk, and yogurt on the market is pure lactic acid bacteria. Its species is called Kefir granules, which is a complex microbial system, mainly composed of some genera and species of lactic acid bacteria, yeast and acetic acid bacteria, and is the most common among lactic acid bacteria.

Lactobacillus, including heterotypic fermentation and isotype, is a very precious thing in microbiology, and all countries in the world attach great importance to it and make great efforts to study its physiological effects on human beings.