kefir

Kefir grains, which are a Probiotic that contain Yeast and live bacteria, are used to make kefir

Kefir (pronounced /kəˈfɪər/ kə-feer ^[1]) (alternately kefīrs, keefir, kephir, kewra, talai, mudu kekiya, milkkefir, búlgaros) is a probiotic^[2] fermented milk drink made with Kefir Grains that originated with shepherds of the North Caucasus region, who discovered that fresh milk carried in leather pouches would occasionally ferment into an effervescent beverage. 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.^[3]

Marco Polo mentions kefir in recounting his travels.^[4]

Overview

Kefir means foam in Turkish. Kefir grains are a combination of bacteria and yeasts in a matrix of proteins, lipids, and sugars, and this symbiotic matrix forms "grains" that resemble cauliflower. For this reason, a complex and highly variable community of lactic acid bacteria and yeasts can be found in these grains.

Kefir grains contain a water soluble polysaccharide known as kefiran, which imparts a rope-like texture and feeling in the mouth; appear in hues ranging from white to yellow; and usually grow to the size of walnuts (although rice-grain-sized grains have been known to develop).

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.^[5] Kefir fermented by small-scale dairies early in the 20th century achieved alcohol levels between 1 and 2 percent, but kefir made commercially with modern methods of production has less than 1% alcohol, possibly due to reduced fermentation time.^[6]

Variations that thrive in various other liquids exist, and they 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.

Kefir grains preparation

Kefir grains preparation is described in the papers by M. Motaghi et al. (1997)^[7] and Semih Ötles and Özlem Çağındı (2003):^[8]

A goat-hide bag, which was washed with sterile water, was filled with pasteurized milk and the intestinal flora of a sheep. It was shaken every hour and was kept for 2 days at a temperature of about 25°C. During 12 weeks, each time the milk coagulated, three quarters of it was replaced with fresh milk. When a polysaccharide layer developed on the surface of the hide it was removed and propagated in pasteurized cow's milk where kefir grains developed. These were grown with fresh milk daily. The historical source of kefir grains is not really known today, despite the paper of M. Motaghi et al. has precise description of how to prepare kefir drinks from kefir grains in Iran.^[7]

Production

90 grams of kefir grains

Production of traditional kefir requires a starter community of kefir grains which are added to the liquid one wishes to ferment. Kefir grains cannot be produced from scratch, but the grains grow during fermentation, and additional grains are produced. Kefir grains can be bought from or donated by other growers.

The traditional, or artisanal, method of making kefir is achieved by directly adding kefir grains (2–10%) to milk in a loosely covered acid proof container which is traditionally agitated once or more times a day. It is not filled to capacity, allowing room for some expansion as the kefiran and carbon dioxide gas produced causes the liquid level to rise. If the container is not light proof it should be stored in the dark to prevent degradation of vitamins and inhibition of the culture. After a period of fermentation lasting around 24 hours, ideally at 20–25 °C (68–77 °F), the grains are removed from the liquid by sieving and reserved as the starter for a fresh amount of liquid. The temperature during fermentation is not critical as long as it is not above one that will kill the culture (about 40 °C / 104 °F), or much below 4 °C (39 °F) where the process will cease.

The fermented liquid which contains live microflora from the grain, may now be consumed as a beverage, used in recipes, or kept aside for several days to undergo a slower secondary fermentation which further thickens and sours the liquid. Without refrigeration the shelf life is two to three days. The grains will enlarge in the process of kefir production, and eventually split. Grains can be dried at room temperature or lyophilized (freeze-dried) or frozen.

The Russian method permits production of kefir on a larger scale, and uses two fermentations. The first step is to prepare the cultures by incubating milk with grains (2–3%), as just described. The grains are then removed by filtration and the resulting liquid mother culture is added to milk (1–3%) which is fermented for 12 to 18 hours.

Kefir can be produced using lyophilized cultures commonly available as a powder from health food shops. 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, and a fresh culture must be obtained.

Preliminary research

One can possibly change the nutrient content of kefir by simply fermenting for shorter or longer periods, possibly with each stage providing value. For instance, kefir over-ripened (which increases the sour taste) significantly increases folic acid content.^[9] One study showed that kefir also may aid in lactose digestion as a catalyst.^[10] However, the study showed that there is simply a lower amount of lactose in kefir than in whole milk, with lactose still having an effect on lactose-intolerant subjects. Flatulence, the most commonly reported symptom of drinking kefir, was shown to be lower by 50% compared to the consumption of milk.^[11]

Researcher Steven Hertzler stated: "Both kefir and yogurt improve lactose digestion simply because some of the bacterial cells give up their lives in the intestinal tract, release their enzymes and digest the lactose. It's a one-shot deal. However, kefir has additional microorganisms that may be able to colonize the intestines and benefit health further by protecting the intestine against disease-causing bacteria."^[11]

The kefiran in kefir has been shown in one study to suppress an increase in blood pressure and reduce serum cholesterol levels in rats.^[12]

Kefir contains compounds that have antimutagenic and antioxidant properties in vitro, although it is not established that these compounds have any physiological properties when kefir is consumed.^[13]

Consumption

Some find kefir too sour on its own and prefer to add flavors or sweeteners. Frozen fruits can be mixed with kefir in a blender to make a smoothie. Kefir is sold with different varieties of fruit and flavors already added, both in the organic/ecologic and non-organic varieties. It is a breakfast, lunch and dinner drink popular across all areas of Russia, Belarus, Ukraine, Poland, Slovakia, the Czech Republic, Hungary, Romania, Moldova, Serbia, Croatia, Bosnia, Norway, Sweden, Estonia, Latvia and Lithuania where it is known as an affordable health drink. It is drunk the same way as milk, often accompanying pastries and other sweets.^{[citation needed]}

Kefir, known as "yogurt de pajaritos" (bird's yogurt), is also commonly consumed in Chile, where it may have been introduced by any of the various waves of migrants from the former Ottoman empire and migrants from Eastern Europe.

The health benefits of kefir have recently made it more popular in the U.S. It can be found at Publix, Trader Joe's, Whole Foods and other grocery stores.^[14]

Different milk types

A glass of kefir in a Polish café

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. Raw milk has been traditionally used.

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.

Milk sugar is, however, not essential for the synthesis of the polysaccharide that makes up the grains (kefiran), and studies have demonstrated that rice hydrolysate is a suitable alternative medium.^[15] 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.^[16]

Culinary uses

As it contains yeasts, kefir can be used to make a sourdough bread. It is also useful as a buttermilk substitute in baking. Kefir is one of the main ingredients in Lithuanian cold beet soup šaltibarščiai (Polish chłodnik), commonly known as cold borscht. Other variations of kefir soups and foods prepared with kefir are popular across the former Soviet Union and Poland. Kefir may be used in lieu of milk on cereal or granola.

Other fermented dairy products

Food portal

References

Further reading

• Katz, Sandor Ellix (2003). Wild Fermentation: The Flavor, Nutrition, and Craft of Live-Culture Foods. Chelsea Green Publishing Company. ISBN 1931498237. 
• Dr. Ted Farnworth editor-in-chief of Medicinal Food News Kefir a Fermented Milk Probiotic

External links

Wikimedia Commons has media related to: Kefir

Look up kefir in Wiktionary, the free dictionary.

Wikibooks has a book on the topic of Cookbook:Kefir

• Zoogloea.com Kefir Making.
• Fermented Foods: Kefir, from the National Center for Home Food Preservation
•  "Kephir". Collier's New Encyclopedia. 1921. 
•  "Kephir". New International Encyclopedia. 1905.