Kefir
- For the Islamic term, see Kaffir.
Kefir (alternately keefir, kephir, kewra, talai, mudu kekiya, milkkefir, búlgaros) is a fermented milk drink that originated in the Caucasus region. It is prepared by inoculating cow, goat, or sheep's milk with kefir grains. Traditional kefir was made in skin bags that were hung near a doorway; the bag would be knocked by anyone passing through the doorway to help keep the milk and kefir grains well mixed.[1]
Overview
Kefir grains are a combination of bacteria and yeasts in a matrix of proteins, lipids, and sugars. This symbiotic matrix forms grains that resemble cauliflower. Today, kefir is becoming increasingly popular due to new research into its health benefits. Many different bacteria and yeasts are found in the kefir grains, which are a complex and highly variable community of micro-organisms.[2]
Traditional kefir is fermented at ambient temperatures, generally overnight. Fermentation of the lactose yields a sour, carbonated, slightly alcoholic beverage, with a consistency similar to thin yogurt.[3] Kefir fermented by small-scale dairies early in the 20th century achieved alcohol levels between 1% and 2%, but kefir made commercially with modern methods of production has less than 1% alcohol, possibly due to reduced fermentation time.[1]
Variations that thrive in various other liquids exist. They may vary markedly from kefir in both appearance and microbial composition. Water kefir (or kefir d'acqua) is grown in water with sugar (sometimes with added dry fruit such as figs, and lemon juice) for a day or more at room temperature.
Making kefir
Production of traditional kefir requires kefir grains which are a gelatinous community of bacteria and yeasts. Kefir grains contain a water soluble polysaccharide known as kefiran that imparts a rope-like texture and feeling in one's mouth. Kefir grains cannot be produced from scratch, but the grains grow during fermentation, and additional grains are produced. Kefir grains can be purchased or acquired from other hobbyists, see below. Kefir grains appear white to yellow and are usually the size of a walnut, but may be as small as a grain of rice.
Health and nutrition
One can change the nutrient content by simply fermenting for shorter or longer periods. Both stages have different healthful benefits. For instance, kefir over-ripened (increases sour taste) significantly increases folic acid content.[4] Kefir also aids in lactose digestion as a catalyst, making it more suitable than other dairy products for those who are lactose intolerant.[5] The kefiran in kefir has been shown to suppress an increase in blood pressure and reduce serum cholesterol levels in rats.[6]
Drinking kefir
While some drink kefir straight, many find it too sour on its own and prefer to add fruits, honey, maple syrup or other flavors or sweeteners. Frozen bananas, strawberries, blueberries or other fruits can be mixed with kefir in a blender to make a smoothie. Vanilla, agave nectar and other flavorings may also be added. It is a breakfast drink popular across all areas of the former Soviet Union, where it it is known as an affordable health drink.
Different milk types
Kefir grains will successfully ferment the milk from most mammals, and will continue to grow in such milk. Typical milks used include cow, goat, and sheep, each with varying organoleptic and nutritional qualities.
In addition, kefir grains will ferment milk substitutes such as soy milk, rice milk, and coconut milk, as well as other sugary liquids including fruit juice, coconut water, beer wort and ginger beer. However, the kefir grains may cease growing if the medium used does not contain all the growth factors required by the bacteria (which are all present in mammalian milk), so it is best to only use excess kefir grains for trying alternative fermentation media.
Milk sugar is, however, not essential for the synthesis of the polysaccharide that makes up the grains (kefiran), and scientific studies have demonstrated that rice hydrolysate is a suitable alternative medium.[7] Additionally, it has been shown that kefir grains will reproduce when fermenting soy milk, although they will change in appearance and size due to the differing proteins available to them.[8]
Culinary uses
Kefir is one of the main ingredients in Lithuanian cold beet soup (šaltibarščiai, commonly known as cold borscht) and Russian summer soup (okroshka). Other variations of kefir soups and foods prepared with kefir are popular across the former Soviet Union.
Others enjoy kefir, in lieu of milk, on cereal or granola.
References
Specific references:
- ^ a b Farnworth, Edward R. (2003). Handbook of Fermented Functional Foods. CRC. ISBN 0-8493-1372-4.
- ^ Lopitz-Otsoa, F (2006). "Kefir: A symbiotic yeast-bacteria community with alleged healthy capabilities" (PDF). Revista Iberoamericana de Micología. 23: 67–74. Retrieved 2007-06-10.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Kowsikowski, F., and V. Mistry. 1997. Cheese and Fermented Milk Foods, 3rd ed, vol. I. F. V. Kowsikowski, L.L.C., Westport, Conn.
- ^ Kneifel, W (1991). "Vitamin profiles of kefirs made from milks of different species". International Journal of Food Science & Technology. 26: 423–428.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Hertzler, Steven R. (2003 May). "Kefir improves lactose digestion and tolerance in adults with lactose maldigestion". Journal of the American Dietetic Association. 103 (5). Elsevier, Inc.: 582–587. doi:10.1053/jada.2003.50111. Retrieved 2007-06-10.
{{cite journal}}: Check date values in:|date=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Maeda, H (2004-12-30). "Effects of an exopolysaccharide (kefiran) on lipids, blood pressure, blood glucose, and constipation". BioFactors. 22 (1–4). IOS Press: 197–200. Retrieved 2007-06-10.
{{cite journal}}: Check date values in:|date=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Maeda, H (2004-08-25). "Structural characterization and biological activities of an exopolysaccharide kefiran produced by Lactobacillus kefiranofaciens WT-2B(T)". Journal of Agricultural and Food Chemistry. 52 (17). American Chemical Society: 5533–8. doi:10.1021/jf049617g. Retrieved 2007-06-10.
{{cite journal}}: Check date values in:|date=(help); Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Abraham, Analía G. (May 1999). "Characterization of kefir grains grown in cows' milk and in soy milk". Journal of Dairy Research. 66 (2). Cambridge University Press: 327–333. doi:10.1017/S0022029999003490. Retrieved 2007-06-09.
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General references:
- Katz, Sandor Ellix (2003). Wild Fermentation: The Flavor, Nutrition, and Craft of Live-Culture Foods. Chelsea Green Publishing Company. ISBN 1-931498-23-7. Retrieved 2007-06-10.
See also
- kumis, ayran, lassi, tibicos and other dairy products
- buttermilk, a fermented dairy product
External links
- Kefir Recipes at Wikibooks
- Fermented Foods: Kefir, from the National Center for Home Food Preservation
- Dominic N. Anfiteatro's kefir site
- Where to get kefir grains (listings by area)
- Finding kefir
- Probiotic composition and therapeutic aspects
