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Kefir ( ; "kefir". Oxford Dictionaries. kefir . dictionary.reference.com alternative spellings: kephir or kefier) is a fermented milk drink similar to a thin yogurt or ayran that is made from kefir grains, a specific type of mesophilic SCOBY. It is prepared by inoculation the milk of cows, goat milk, or sheep milk with kefir grains.
Kefir is a common breakfast, lunch or dinner drink consumed in countries of West Asia and Eastern Europe. Kefir is consumed at any time of the day, such as alongside European pastries like zelnik (zeljanica), burek and banitsa/gibanica, as well as being an ingredient in cold soups.
The word kefir, which is of North Caucasian origin, became an international word, having originally spread to Russia, Central European and Eastern European countries at least by 1884.
A Russian borrowing in English, its ultimate origin is unknown, though one theory is that the word comes from köpür in Old Turkic. More likely is another Caucasian origin; compare Georgian კეფირი (k'epiri), Mingrelian ქიფური (kipuri), Ossetian къӕпы (k'æpy), and Karachay-Balkar гыпы (gıpı). The p to f transformation may indicate possible transmission to Russian through Arabic rtl=yes (kifīr), which would have served as a lingua franca in the Muslim parts of the Caucasus.
Traditional kefir was made in goatskin bags that were hung near a doorway; the bags would be knocked by anyone passing through to keep the milk and kefir grains well mixed. In Karachay-Balkar, gıpı has a connection with gıpıt (wineskin). It was under the name wineskin that Karachay kefir was distributed in the second half of the 19th century and at the beginning of the 20th century. (2025). 9785020380431, .Institute of Ethnology and Anthropology. N.N. Miklouho-Maclay RAS. Science. ISBN 9785020380431 Kefir spread from the former Soviet Union to the rest of Europe, Canada, Japan, and the United States by the early 21st century. It has become known in parts of Latin America as búlgaros, or "".
The kefir grains initiating the fermentation are initially created by auto-aggregations of Lactobacillus kefiranofaciens and Maudiozyma turicensis or M. humilis, where multiple biofilm producers cause the surfaces to adhere which form a three dimensional microcolony. The biofilm is a matrix of Polysaccharide called kefiran, which is composed of equal proportions of glucose and galactose. It resembles small cauliflower grains, with color ranging from white to creamy yellow. A complex and highly variable symbiotic community can be found in these grains, which can include acetic acid bacteria (such as Acetobacter aceti and Acetobacter rasens), yeasts (such as Candida kefyr, K. lactis, K. marxianus , Saccharomyces cerevisiae, M. turicensis) and a number of Lactobacillus species, such as L. parakefiri, L. kefiranofaciens (and subsp. kefirgranum), L. kefiri, L. brevis , etc. While some microbes predominate, Lactobacillus species are always present. The microbe flora can vary between batches of kefir due to factors such as the kefir grains rising out of the milk while fermenting or curds forming around the grains, as well as temperature. Additionally, Tibetan kefir composition differs from that of the Russian kefir, Irish kefir, Taiwan kefir and Turkey fermented beverage with kefir. In recent years, the use of Freeze-drying starter culture has become common due to stability of the fermentation result, because the species of microbes are selected in laboratory conditions, as well as easy transportation.
During fermentation, changes in the composition of ingredients occur. Lactose, the sugar present in milk, is broken down mostly to lactic acid by the lactic acid bacteria, which results in acidification. Propionibacteria further break down some of the lactic acid into propionic acid (these bacteria also carry out the same fermentation in Swiss cheese). Other substances that contribute to the flavor of kefir are pyruvic acid, acetic acid, diacetyl and acetoin (both of which contribute a "buttery" flavor), citric acid, acetaldehyde, and amino acids resulting from protein breakdown.
Kefir contains byproducts of the fermentation process, including carbon dioxide and ethanol.
In addition to bacteria, kefir often contains strains of yeast that can metabolize lactose, such as Kluyveromyces marxianus, Kluyveromyces lactis, and Saccharomyces fragilis, as well as strains of yeast that do not metabolize lactose, including Saccharomyces cerevisiae, Torulaspora delbrueckii, and Kazachstania unispora. The nutritional significance of these strains is not currently known with certainty.
The resulting fermented liquid may be drunk, used in recipes, or kept aside in a sealed container for additional time to undergo a secondary fermentation. Because of its acidity the beverage should not be stored in reactive metal containers such as aluminium, copper, or zinc, as these may leach into it over time. The shelf life, unrefrigerated, is up to thirty days.
The Russian method permits production of kefir on a larger scale and uses two fermentations. The first step is to prepare the cultures by inoculating milk with 2–3% grains as described. The grains are then removed by filtration and 1–3% of the resulting liquid mother culture is added to milk and fermented for 12 to 18 hours.
Kefir can be made using freeze-drying cultures commonly available in powder form from health food stores. A portion of the resulting kefir can be saved to be used a number of times to propagate further fermentations but ultimately does not form grains.
In Taiwan, researchers were able to produce kefir in a laboratory using microorganisms isolated from kefir grains. They report that the resulting kefir drink had chemical properties similar to homemade kefir.
Milk sugar is not essential for the synthesis of the polysaccharide that makes up the grains (kefiran), and rice hydrolysate is a suitable alternative medium. Additionally, kefir grains will reproduce when fermenting soy milk, although they will change in appearance and size due to the differing proteins available to them.
A variation of kefir grains that thrive in sugary water also exists, see Tibicos (or tibicos), and can vary markedly from milk kefir in both appearance and microbial composition.
In Estonia, kefir is also often mixed with kama and eaten as a snack or a quick breakfast.
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