Kefir grains are a combination of probiotic bacteria and yeasts in a matrix of proteins, lipid and sugars. They are grown in milk (most commonly cow or goat milk) for a day or more at room temperature. The resulting beverage is called kefir. It is a faintly fizzy and slightly alcoholic drink, similar to yoghurt.
The exact combination of bacteria and yeasts vary between cultures. To ensure consistency, commercial producers now generally use a powdered starter culture rather than grains. However, such cultures do not form grains or continue to culture indefinitely, making kefir grains the preferred choice for individuals. Kefir grains grow over time. Excess grains may be stored, eaten or given away. If you would like to request kefir grains, or have some to share, please visit the Live Kefir Grains database.
Variations that thrive in various other liquids (typically fruit or sugar based solutions) exist. They may vary markedly from milk kefir in both appearance and microbial composition. The beverage made from them is called kefir d'acqua or water-kefir.
For more information, see Dominic N. Anfiteatro’s kefir in-site.
See also other dairy products and Kombucha