derives from kefir food product A fermented milk drink made from milk. It is prepared by inoculating cow, goat, or sheep's milk with kefir grains, a combination of bacteria and yeasts in a matrix of proteins, lipids, and sugars. This symbiotic matrix forms "grains" that resemble cauliflower. Many different bacteria and yeasts are found in the kefir grains, which are a complex and highly variable community of micro-organisms termed probiotics. mammalian milk (cultured) cultured dairy product