Kefir

Kefir has been found in graves in the Bronze Age Xiaohe Cemetery, dating back 3,600 years.{{cite journal |doi=10.1016/j.cell.2024.08.008 |title=Bronze Age cheese reveals human-Lactobacillus interactions over evolutionary history |date=2024 |last1=Liu |first1=Yichen |last2=Miao |first2=Bo |last3=Li |first3=Wenying |last4=Hu |first4=Xingjun |last5=Bai |first5=Fan |last6=Abuduresule |first6=Yidilisi |last7=Liu |first7=Yalin |last8=Zheng |first8=Zequan |last9=Wang |first9=Wenjun |last10=Chen |first10=Zehui |last11=Zhu |first11=Shilun |last12=Feng |first12=Xiaotian |last13=Cao |first13=Peng |last14=Ping |first14=Wanjing |last15=Yang |first15=Ruowei |last16=Dai |first16=Qingyan |last17=Liu |first17=Feng |last18=Tian |first18=Chan |last19=Yang |first19=Yimin |last20=Fu |first20=Qiaomei |journal=Cell |volume=187 |issue=21 |pages=5891–5900.e8 |doi-access=free |pmid=39326418 }}

The word kefir, which is of North Caucasian origin,{{cite journal |vauthors=Prado MR, Blandón LM, Vandenberghe LP, Rodrigues C, Castro GR, Thomaz-Soccol V, Soccol CR |date=30 October 2015 |title=Milk kefir: composition, microbial cultures, biological activities, and related products |journal=Frontiers in Microbiology |volume=6 |pages=1177 |doi=10.3389/fmicb.2015.01177 |pmc=4626640 |pmid=26579086 |doi-access=free }} became an international word, having originally spread to Russia, Central European and Eastern European countries at least by 1884,{{cite web |title=Origin of KEFIR |date=27 April 2023 |url=http://www.merriam-webster.com/dictionary/kefir |publisher=Merriam-Webster Dictionary Online |access-date=15 October 2012 |archive-date=18 April 2019 |archive-url=https://web.archive.org/web/20190418205119/https://www.merriam-webster.com/dictionary/kefir |url-status=live }}

A Russian borrowing in English, its ultimate origin is unknown, though one theory is that the word comes from {{Lang|otk-latn|köpür}} in Old Turkic.{{cite encyclopedia |dictionary=The American Heritage Dictionary of the English Language |entry=kefir |entry-url=http://www.yourdictionary.com/kefir |access-date=11 December 2014 |archive-date=18 April 2019 |archive-url=https://web.archive.org/web/20190418205121/https://www.yourdictionary.com/kefir |url-status=live |title=Kefir dictionary definition | kefir defined }} More likely is another Caucasian origin; compare Georgian {{Lang|ka|კეფირი}} ({{Lang|ka-latn|k’epiri}}), Mingrelian {{Lang|xmf|ქიფური}} ({{Lang|xmf-latn|kipuri}}), Ossetian {{Lang|os-cyrl|къӕпы}} ({{Lang|os-latn|k’æpy}}), and Karachay-Balkar {{Lang|krc-cyrl|гыпы}} ({{Lang|krc-latn|gıpı}}). The p to f transformation may indicate possible transmission to Russian through Arabic {{Lang|ar|كِفِير|rtl=yes}} ({{Lang|ar-latn|kifīr}}), which would have served as a lingua franca in the Muslim parts of the Caucasus.{{Cn|date=February 2025}}

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.{{cite book |vauthors=Willey JM, Sherwood L, Woolverton CJ, Prescott LM, Harley JP |title=Prescott, Harley, and Klein's Microbiology |url=https://archive.org/details/Microbiology_7_edition_by_Joanne_Willey_Linda_Sherwood_Chris_Woolverton |edition=7th |location=London |publisher=McGraw–Hill |page=[https://archive.org/details/Microbiology_7_edition_by_Joanne_Willey_Linda_Sherwood_Chris_Woolverton/page/n1060 1040] |isbn=978-0-07-110231-5 |year=2008 }} In Karachay-Balkar, {{Lang|krc-latn|gıpı}} has a connection with {{Lang|krc-latn|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.{{Cite web |author=Ibragim Shamanov |title=Milk. How much there is in this word... |publisher=Elbrusoid |url=http://www.elbrusoid.org/articles/poznat/387255/ |date=26 April 2006 |access-date=14 June 2023 |archive-date=6 December 2020 |archive-url=https://web.archive.org/web/20201206091838/http://www.elbrusoid.org/articles/poznat/387255/ |url-status=live }}{{Cite book |last1=Karaketov |title=Karachays. Balkars |last2=Sabanchiev |publisher=.Institute of Ethnology and Anthropology. N.N. Miklouho-Maclay RAS. Science |year=2014 |isbn=978-5-02-038043-1 |location=Moscow |pages= }} Kefir spread from the former Soviet Union to the rest of Europe, Canada, Japan, and the United States by the early 21st century.{{cite web |vauthors=Sando L |title=Kefir Consumption—a Growing Culture |url=http://milkgenomics.org/article/kefir-consumption-a-growing-culture/ |publisher=International Milk Genomics Consortium |access-date=19 August 2017 |date=September 2015 |archive-url=https://web.archive.org/web/20170819192537/http://milkgenomics.org/article/kefir-consumption-a-growing-culture/ |archive-date=19 August 2017 |url-status=dead }}{{cite journal |vauthors=Arslan S|title=A review: chemical, microbiological and nutritional characteristics of kefir |journal=CyTA – Journal of Food |date=26 November 2014 |volume=13 |issue=3 |pages=340–345 |doi=10.1080/19476337.2014.981588 |doi-access=free }} It has become known in parts of Latin America as {{Lang|es|búlgaros}}, or "Bulgarians".{{Cn|date=February 2025}}

File:Kefirpilze.jpg

Traditional kefir is fermented at ambient temperatures, generally overnight. Fermentation of the lactose yields a sour, carbonated, slightly alcoholic beverage, with a consistency and taste similar to drinkable yogurt.{{cite book |vauthors=Kowsikowski F, Mistry V |date=1997 |title=Cheese and Fermented Milk Foods |edition=3rd |volume=I |publisher=FV Kowsikowski |location=Westport, Conn. |isbn=978-0-9656456-0-7 }}

The kefir grains initiating the fermentation are initially created by auto-aggregations of Lactobacillus kefiranofaciens and Maudiozyma turicensis,{{cite journal |last1=Liu |first1=F. |last2=Hu |first2=Z.-D. |last3=Yurkov |first3=A. |last4=Chen |first4=X.-H. |last5=Bao |first5=W.-J. |last6=Ma |first6=Q. |last7=Zhao |first7=W.-N. |last8=Pan |first8=S. |last9=Zhao |first9=X.-M. |last10=Liu |first10=J.-H. |last11=Wang |first11=Q.-M. |last12=Boekhout |first12=T. |title=Saccharomycetaceae : delineation of fungal genera based on phylogenomic analyses, genomic relatedness indices and genomics-based synapomorphies |journal=Persoonia – Molecular Phylogeny and Evolution of Fungi |date=30 June 2024 |volume=52 |issue=1 |pages=1–21 |doi=10.3767/persoonia.2024.52.01|pmid=39161631 |pmc=11319838 }} where multiple biofilm producers cause the surfaces to adhere which form a three dimensional microcolony.{{cite journal |vauthors=Wang SY, Chen KN, Lo YM, Chiang ML, Chen HC, Liu JR, Chen MJ |title=Investigation of microorganisms involved in biosynthesis of the kefir grain |journal=Food Microbiology |volume=32 |issue=2 |pages=274–285 |date=December 2012 |pmid=22986190 |doi=10.1016/j.fm.2012.07.001 }}{{cite journal |vauthors=Wyder MT, Meile L, Teuber M |title=Description of Saccharomyces turicensis sp. nov., a new species from kefyr |journal=Systematic and Applied Microbiology |volume=22 |issue=3 |pages=420–425 |date=September 1999 |pmid=10553294 |doi=10.1016/S0723-2020(99)80051-4 |bibcode=1999SyApM..22..420W }}{{cite journal |author1=Jong-Hwa Kim |author2=Kiyoung Kim |author3=Rungravee Kanjanasuntree |author4=Wonyong Kim |title=Kazachstania turicensis CAU Y1706 ameliorates atopic dermatitis by regulation of the gut–skin axis |journal=Journal of Dairy Science |year=2019 |volume=102 |issue=4 |pages=2854–2862 |doi=10.3168/jds.2018-15849 |pmid=30738679 |s2cid=73448395 |doi-access=free }} The biofilm is a matrix of heteropolysaccharides 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, Saccharomyces cerevisiae, M. turicensis) and a number of Lactobacillus species, such as L. parakefiri, L. kefiranofaciens (and subsp. kefirgranum{{cite journal |vauthors=Vancanneyt M, Mengaud J, Cleenwerck I, Vanhonacker K, Hoste B, Dawyndt P, Degivry MC, Ringuet D, Janssens D, Swings J |title=Reclassification of Lactobacillus kefirgranum Takizawa et al. 1994 as Lactobacillus kefiranofaciens subsp. kefirgranum subsp. nov. and emended description of L. kefiranofaciens Fujisawa et al. 1988 |journal=International Journal of Systematic and Evolutionary Microbiology |volume=54 |issue=Pt 2 |pages=551–556 |date=March 2004 |pmid=15023974 |doi=10.1099/ijs.0.02912-0 |doi-access=free }}), L. kefiri,{{cite journal |vauthors=Federici F, Manna L, Rizzi E, Galantini E, Marini U |title=Draft Genome Sequence of Lactobacillus kefiri SGL 13, a Potential Probiotic Strain Isolated from Kefir Grains |journal=Microbiology Resource Announcements |volume=7 |issue=4 |pages=e00937–18, e00937–18 |date=August 2018 |pmid=30533877 |pmc=6256422 |doi=10.1128/MRA.00937-18 |veditors=Dennehy JJ }} etc. While some microbes predominate, Lactobacillus species are always present.{{cite journal |vauthors=de Oliveira Leite AM, Miguel MA, Peixoto RS, Rosado AS, Silva JT, Paschoalin VM |title=Microbiological, technological and therapeutic properties of kefir: a natural probiotic beverage |journal=Brazilian Journal of Microbiology |volume=44 |issue=2 |pages=341–349 |date=October 2013 |pmid=24294220 |pmc=3833126 |doi=10.1590/S1517-83822013000200001 }} 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.{{cite journal |first1=Veronique |last1=Ninane |first2=Gilbert |last2=Berben |first3=Jean-Michel |last3=Romne |first4=Robert |last4=Oger |url=http://www.bib.fsagx.ac.be/base/text/v9n3/191.pdf |title=Variability of the microbial abundance of kefir grain starter cultivated in partially controlled conditions |journal=Biotechnologie, Agronomie, Société et Environnement |year=2005 |volume=5 |issue=3 |pages=191–194 |url-status=dead |archive-url=https://web.archive.org/web/20100216184319/http://www.bib.fsagx.ac.be/base/text/v9n3/191.pdf |archive-date=16 February 2010 }} 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-dried 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.{{cite journal |vauthors=Kourkoutas Y, Kandylis P, Panas P, Dooley JS, Nigam P, Koutinas AA |title=Evaluation of freeze-dried kefir coculture as starter in feta-type cheese production |journal=Applied and Environmental Microbiology |volume=72 |issue=9 |pages=6124–6135 |date=September 2006 |pmid=16957238 |pmc=1563647 |doi=10.1128/AEM.03078-05 |bibcode=2006ApEnM..72.6124K }}{{cite journal |vauthors=Mei J, Guo Q, Wu Y, Li Y |title=Microbial diversity of a Camembert-type cheese using freeze-dried Tibetan kefir coculture as starter culture by culture-dependent and culture-independent methods |journal=PLOS ONE |volume=9 |issue=10 |pages=e111648 |date=31 October 2014 |pmid=25360757 |pmc=4216126 |doi=10.1371/journal.pone.0111648 |bibcode=2014PLoSO...9k1648M |veditors=Al-Ahmad A |doi-access=free }}{{cite journal |vauthors=Nikolaou A, Sgouros G, Mitropoulou G, Santarmaki V, Kourkoutas Y |title=Freeze-Dried Immobilized Kefir Culture in Low Alcohol Winemaking |journal=Foods |volume=9 |issue=2 |pages=115 |date=January 2020 |pmid=31973003 |pmc=7073665 |doi=10.3390/foods9020115 |doi-access=free }}

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.{{cite journal |last=Van Wyk |first=Jessy |title=Chapter 12 – Kefir: The Champagne of Fermented Beverages |journal=Fermented Beverages |volume=5 |pages=473–527 |date=2019 |doi=10.1016/B978-0-12-815271-3.00012-9 |isbn=978-0-12-815271-3 |s2cid=108073995 }}

During the fermentation process, bacteria and yeast break lactose down into glucose and galactose.{{Cite journal |last1=Rosa |first1=Damiana D. |last2=Dias |first2=Manoela M. S. |last3=Grześkowiak |first3=Łukasz M. |last4=Reis |first4=Sandra A. |last5=Conceição |first5=Lisiane L. |last6=Peluzio |first6=Maria do Carmo G. |date=June 2017 |title=Milk kefir: nutritional, microbiological and health benefits |url=https://www.cambridge.org/core/journals/nutrition-research-reviews/article/milk-kefir-nutritional-microbiologic-and-health-benefits/1393DC2B8E5F08B0BE7BD58F030D387B |journal=Nutrition Research Reviews |volume=30 |issue=1 |pages=82–96 |doi=10.1017/S0954422416000275 |pmid=28222814 |s2cid=4644552 |issn=0954-4224 |quote=Approximately 30 % of milk lactose is hydrolysed by the β-galactosidase enzyme, turning lactose into glucose and galactose. |url-access=subscription }} As a result of the fermentation, lactose levels are decreased by 20–30% with respect to the initial lactose levels present in the milk.{{Cite journal |last1=Irigoyen |first1=A. |last2=Arana |first2=I. |last3=Castiella |first3=M. |last4=Torre |first4=P. |last5=Ibáñez |first5=F. C. |date=1 May 2005 |title=Microbiological, physicochemical, and sensory characteristics of kefir during storage |url=https://www.sciencedirect.com/science/article/pii/S0308814604003723 |journal=Food Chemistry |volume=90 |issue=4 |pages=613–620 |doi=10.1016/j.foodchem.2004.04.021 |issn=0308-8146 |quote=Lactose was consumed during the 24 h fermentation period, and lactose levels decreased by 20–25% with respect to the initial lactose levels present in the milk. Levels then held practically constant over the storage period. [28 days of storage at 5 ± 1 °C] |url-access=subscription }} One study found that when people with lactose intolerance consumed the same amount of lactose in milk, kefir or yogurt products, the latter two showed significantly reduced symptoms of lactose intolerance during the first 8 hours after consumption.{{Cite journal |last1=Hertzler |first1=Steven R. |last2=Clancy |first2=Shannon M. |date=1 May 2003 |title=Kefir improves lactose digestion and tolerance in adults with lactose maldigestion |url=https://www.sciencedirect.com/science/article/pii/S0002822303002074 |journal=Journal of the American Dietetic Association |volume=103 |issue=5 |pages=582–587 |doi=10.1053/jada.2003.50111 |pmid=12728216 |issn=0002-8223|access-date=21 October 2022 |archive-date=11 November 2019 |archive-url=https://web.archive.org/web/20191111100949/https://www.sciencedirect.com/science/article/pii/S0002822303002074 |url-status=live |url-access=subscription }} This result suggests that yoghurt and kefir might be suitable for people with lactose intolerance. However, the long-term impact of kefir consumption on lactose intolerance has not been studied. It has also been shown that fermented milk products have a slower transit time than milk, which may further improve lactose digestion.{{cite journal |vauthors=Farnworth ER |title=Kefir – a complex probiotic |journal=Food Science and Technology Bulletin: Functional Foods |year=2005 |issue=1 |pages=1–17 |doi=10.1616/1476-2137.13938 |url=http://www.kefir.it/kefir_probiotic.pdf |volume=2 |url-status=dead |archive-url=https://web.archive.org/web/20131029195329/http://www.kefir.it/kefir_probiotic.pdf |archive-date=29 October 2013 |citeseerx=10.1.1.583.6014 }}

Kefir contains a small amount of ethanol.{{cite journal |vauthors=Laureys D, De Vuyst L |title=Microbial species diversity, community dynamics, and metabolite kinetics of water kefir fermentation |journal=Applied and Environmental Microbiology |volume=80 |issue=8 |pages=2564–2572 |date=April 2014 |pmid=24532061 |pmc=3993195 |doi=10.1128/aem.03978-13 |bibcode=2014ApEnM..80.2564L |veditors=Griffiths MW }} The level of ethanol in kefir can vary by production method. A 2016 study of kefir sold in Germany showed an ethanol level of only 0.02 g per litre, which was attributed to fermentation under controlled conditions allowing the growth of Lactobacteria only, but excluding the growth of other microorganisms that generate much higher amounts of ethanol.{{cite journal |vauthors=Gorgus E, Hittinger M, Schrenk D |title=Estimates of Ethanol Exposure in Children from Food not Labeled as Alcohol-Containing |journal=Journal of Analytical Toxicology |volume=40 |issue=7 |pages=537–542 |date=September 2016 |pmid=27405361 |pmc=5421578 |doi=10.1093/jat/bkw046 }} A 2008 study of German commercial kefir found levels of 0.002–0.005% of ethanol.{{cite book |vauthors=Farnworth ER|title=Handbook of fermented functional foods |publisher=CRC Press |location=Boca Raton |year=2008 |isbn=978-1-4200-5328-9 |oclc=646745830 |edition=second }} Kefir produced by small-scale dairies in Russia in the early 20th century had 1–2% ethanol.

{{Infobox nutritional value

| name=Kefir, plain

| water=87 g

| kcal=52

| protein=3.56 g

| fat=0.96 g

| carbs=7.48 g

| fiber=0 g

| sugars=6.91 g

| calcium_mg=124

| iron_mg=0.04

| magnesium_mg=12

| phosphorus_mg=100

| potassium_mg=159

| sodium_mg=38

| zinc_mg=0.45

| vitC_mg=0.8

| thiamin_mg=0.03

| riboflavin_mg=0.172

| niacin_mg=0.128

| vitB6_mg=0.059

| folate_ug=18

| vitB12_ug=0.3

| vitA_ug=174

| vitK_ug=0.6

| note=[https://fdc.nal.usda.gov/food-details/2705394/nutrients Link to Full Report from USDA FoodData Central]

}}

Plain kefir is 87% water, 7% carbohydrates, 4% protein, and 1% fat (table). In a reference amount of {{cvt|100|g}}, kefir provides 52 calories of food energy, and contains moderate amounts (10-19% of the Daily Value, DV) of vitamin A, vitamin B₁₂, riboflavin, and calcium (table).

Kefir contains byproducts of the fermentation process, including carbon dioxide and ethanol.{{cite journal |vauthors=Ahmed Z, Wang Y, Ahmad A, Khan ST, Nisa M, Ahmad H, Afreen A |title=Kefir and health: a contemporary perspective |journal=Critical Reviews in Food Science and Nutrition |volume=53 |issue=5 |pages=422–434 |date=2013 |pmid=23391011 |doi=10.1080/10408398.2010.540360 |s2cid=5166812 }}{{better source|date=May 2025}}

Probiotic bacteria found in kefir products include: Lactobacillus acidophilus, Bifidobacterium bifidum, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, Lactobacillus kefiranofaciens, Lactococcus lactis, and Leuconostoc species.{{cite journal |vauthors=Guzel-Seydim ZB, Kok-Tas T, Greene AK, Seydim AC |title=Review: functional properties of kefir |journal=Critical Reviews in Food Science and Nutrition |volume=51 |issue=3 |pages=261–268 |date=March 2011 |pmid=21390946 |doi=10.1080/10408390903579029 |s2cid=19963871 }}{{cite journal |vauthors=Farnworth ER|title=Kefir-a complex probiotic |journal=Food Science and Technology Bulletin: Functional Foods |date=4 April 2005 |volume=2 |issue=1 |pages=1–17 |doi=10.1616/1476-2137.13938 |url=http://kefir.it/kefir_probiotic.pdf |access-date=20 December 2014 |url-status=dead |archive-url=https://web.archive.org/web/20140514095454/http://www.kefir.it/kefir_probiotic.pdf |archive-date=14 May 2014 |citeseerx=10.1.1.583.6014 }} Lactobacilli in kefir may exist in concentrations varying from approximately 1 million to 1 billion colony-forming units per milliliter, and are the bacteria responsible for the synthesis of the polysaccharide kefiran.

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 unknown.{{Cn|date=February 2025}}

File:Kefir-grains-90grams.jpg

File:Kefir-insieme.jpg

Modern kefir is made by adding kefir grains to milk typically at a proportion of 2–5% grains-to-milk. The mixture is then placed in a corrosion-resistant container, such as a glass jar, and stored preferably in the dark to prevent degradation of light-sensitive vitamins. After a period between 12 and 24 hours of fermentation at mild temperature, ideally {{convert|20|–|25|C|F}}, the grains are strained from the milk using a corrosion-resistant (stainless steel or plastic) utensil and kept to produce another batch. During the fermentation process the grains enlarge and eventually split forming new units.

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.{{cite journal |vauthors=Motaghi M, Mazaheri M, Moazami N, Farkhondeh A, Fooladi MH, Goltapeh EM |journal=World Journal of Microbiology and Biotechnology |volume=13 |pages=579–581 |url=http://kefir.ilbello.com/articoli/k4.pdf |title=Kefir production in Iran |doi=10.1023/A:1018577728412 |year=1997 |s2cid=85138812 |issue=5 |url-status=dead |archive-url=https://web.archive.org/web/20081201121027/http://kefir.ilbello.com/articoli/k4.pdf |archive-date=1 December 2008 }}

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.{{cite web |title=Section Fabrication of kefir|first=Cathy J.|last=Saloff-Coste|url=http://coproweb.free.fr/kefiranglais.htm|year=2002|url-status=live|archive-url=https://web.archive.org/web/20131112092352/http://dwb.unl.edu/Teacher/NSF/C11/C11Links/rawhealth.net/kefir2.htm |archive-date=12 November 2013 }}

Kefir can be made using freeze-dried 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.{{Cn|date=February 2025}}

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.{{cite journal |vauthors=Chen TH, Wang SY, Chen KN, Liu JR, Chen MJ |title=Microbiological and chemical properties of kefir manufactured by entrapped microorganisms isolated from kefir grains |journal=Journal of Dairy Science |volume=92 |issue=7 |pages=3002–3013 |date=July 2009 |pmid=19528577 |doi=10.3168/jds.2008-1669 |url=http://ntur.lib.ntu.edu.tw/bitstream/246246/177484/1/04.pdf |doi-access=free |access-date=10 June 2012 |archive-date=7 October 2013 |archive-url=https://web.archive.org/web/20131007202451/http://ntur.lib.ntu.edu.tw/bitstream/246246/177484/1/04.pdf |url-status=live }}

Kefir grains will ferment the milk from most mammals and will continue to grow in such milk. Typical animal milks used include cow, goat, and sheep, each with varying organoleptic (flavor, aroma, and texture) and nutritional qualities. Raw milk has been traditionally used.

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.{{cite journal |vauthors=Maeda H, Zhu X, Suzuki S, Suzuki K, Kitamura S |title=Structural characterization and biological activities of an exopolysaccharide kefiran produced by Lactobacillus kefiranofaciens WT-2B(T) |journal=Journal of Agricultural and Food Chemistry |volume=52 |issue=17 |pages=5533–5538 |date=August 2004 |pmid=15315396 |doi=10.1021/jf049617g |url=https://pubs.acs.org/doi/10.1021/jf049617g |access-date=26 April 2023 |archive-date=26 April 2023 |archive-url=https://web.archive.org/web/20230426094933/https://pubs.acs.org/doi/10.1021/jf049617g |url-status=live |url-access=subscription }} 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.{{cite journal |vauthors=Abraham AG, De Antoni GL |title=Characterization of kefir grains grown in cows' milk and in soya milk |journal=The Journal of Dairy Research |volume=66 |issue=2 |pages=327–333 |date=May 1999 |pmid=10376251 |doi=10.1017/S0022029999003490 |s2cid=32190162 }}

A variation of kefir grains that thrive in sugary water also exists, see water kefir (or tibicos), and can vary markedly from milk kefir in both appearance and microbial composition.{{cite journal | last=Guzel-Seydim | first=Zeynep B. | last2=Gökırmaklı | first2=Çağlar | last3=Greene | first3=Annel K. | title=A comparison of milk kefir and water kefir: Physical, chemical, microbiological and functional properties | journal=Trends in Food Science & Technology | volume=113 | date=2021 | doi=10.1016/j.tifs.2021.04.041 | pages=42–53 | url=https://linkinghub.elsevier.com/retrieve/pii/S0924224421003010}}

File:Chlodnik_(Cold_Borscht).jpg {{Lang|lt|šaltibarščiai}}, also known as "cold borscht", consumed in Eastern European countries]]

As it contains Lactobacillus bacteria, kefir can be used to make a sourdough starter.{{cite book |last=Zak |first=Zuza |title=Amber & Rye: A Baltic Food Journey |year=2021 |publisher=Interlink Books |isbn=978-1-62-371900-5 |page=64}} It is also useful as a buttermilk substitute in baking. Kefir is one of the main ingredients in cold borscht soup in Lithuania, also known in Poland as Lithuanian cold soup ({{Lang|pl|chłodnik litewski}}), and other countries. The kefir-based soup okroshka is common across the former Soviet Union. Kefir may be used in place of milk on cereal, granola, milkshakes, salad dressing, ice cream, smoothies and soup.{{Cn|date=February 2025}}

In Estonia, kefir is also often mixed with kama and eaten as a snack or a quick breakfast.{{cite book |last=Zak |first=Zuza |title=Amber & Rye: A Baltic Food Journey |year=2021 |publisher=Interlink Books |isbn=978-1-62-371900-5 |page=232}}

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• {{cite web | last=Golembiewski | first=Kate | title=World's Oldest Cheese Stood Alone for 3,600 Years | website=The New York Times | date=25 September 2024 | url=https://www.nytimes.com/2024/09/25/science/oldest-cheese-kefir-xinjiang.html | access-date=26 September 2024}}

{{Reflist|30em}}

{{Wiktionary|kefir}}

{{Commons category}}

• [https://web.archive.org/web/20041216015658/http://www.uga.edu/nchfp/publications/nchfp/factsheets/kefir.html Fermented Foods: Kefir], from the National Center for Home Food Preservation
• {{Cite Collier's|wstitle=Kephir |short=x}}
• {{Cite NIE |wstitle=Kephir |year=1905 |short=x}}

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