ABSTRACT
This chapter describes the nutritional importance and health promoting properties of kefir and koumiss. It also describes the history, microbiology and biochemistry of kefir and koumiss. Worldwide, the known fermented milk products are yogurt, kefir, koumiss, sour cream, and cheeses. The kefir grains contain active microorganisms and when added to fresh milk, they produce kefir. Due to its abundant health benefits, kefir has gained popularity as a functional healthy probiotic food throughout the world. Koumiss is similar to the kefir; however it is prepared by a liquid starter culture in contrast to the solid kefir grains used in kefir production. Koumiss is a traditional milk beverage produced from fermentation of mares' milk by indigenous microorganisms. The microbes present in the kefir and koumiss live symbiotically, yet the microbial population composition in them may differ due to the origins, methods and substrates used for preparation of these products.
