Kefir (alternately kephir, kewra, talai, mudu kekiya, matsoun, matsoni, waterkefir, milkkefir) is a fermented milk drink originating in the Caucasus.

The drink is prepared by inoculating cow's or goat's milk with the grains - or "beads" - of previous kefir batches. Kefir grains are a combination of probiotic bacteria and yeasts in a matrix of proteins, lipids and sugars. Lactobacillus acidophilus and Saccharomyces kefir are widely used, though the exact combination of bacteria and yeasts vary between cultures. The milk is incubated at room temperature for a day or more, during which the lactose is fermented. The resulting beverage is a sour, carbonated, slightly alcoholic drink. The consistency is similar to yoghurt. In fact, most American "kefir" lacks both carbonation and fermentation and is nothing more than liquid yogurt.

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.

Variations that thrive in various other liquids exist. They may vary markedly from waterkefir or kefir in both appearance and microbial composition. Waterkefir (or kefir d'acqua) is grown in water with sugar, dry fruit such as figs and lemon juice for a day or more at room temperature.

In Chile this beverage is called "Yoghurt de Pajaritos".

Due to the slight amount of alcohol in kefir, Russians often use it as a hangover cure.

See also: kumis, Kombucha and other dairy products.

Further Reading

For more information, see:

• National Center for Home Food Preservation - Kefir
• Dominic N. Anfiteatro's kefir in-site
• Kefir FAQ at Greg's Grains

For more information in Portuguese, see Carlos F. Dias Jr.'s in-site.

For an international kefir grains database, see Adnan's Live Kefir grains site.