Abstract: Kefir is an acidic,viscous dairy beverage fermented by the actions of numerous species of lactic acid bacteria and yeasts embedded in the “kefir grain” in the milk,and now it can be found all over the world.Kefir has shown to possess some probiotic properties such as pathogen-resistant activity,probiotic-promoting activity,toxin-protection activity,immunoregulation activity,cholesterol-lowering activity,antitumor activity and alleviating the symptoms of lactose maldigestion.Hence it has a wide and potential application on the field of pharmaceutical and food industry.To give insights into the diversity of microflora in Kefir,culture-dependent and culture-independent methods have been taken into consideration.In order to develop a commercial “kefir-type” beverage,some pure cultures,isolated from kefir grain,have been combined and taken as starter in modern production of kefir,and it has become a hot topic to a large number of researchers.Although researchers attempted to develop a commercial “kefir-type” beverage,it is not success yet.Maybe it has something to do with the microbial diversity presenting in kefir grains and their interactions,or some microflora presenting in different grains.In this review,structure and growth mechanism of kefir grain,probiotic properties,application and production of kefir were reviewed.

Key words: Kefir, kefir grain, probiotic property, production