Yogurt (UK:/ˈjɒɡərt/;US:/ˈjoʊɡərt/,[1] fromOttoman Turkish:یوغورت,Turkish:yoğurt;[a] also spelledyoghurt,yogourt oryoghourt) is a food produced by bacterialfermentation of milk.[2] Fermentation of sugars in the milk by these bacteria produceslactic acid, which acts onmilk protein to give yogurt itstexture and characteristic tart flavor.[2] Cow's milk is most commonly used to make yogurt. Milk fromwater buffalo, goats,ewes,mares, camels, andyaks is also used to produce yogurt. The milk used may behomogenized or not. It may bepasteurized orraw. Each type of milk produces substantially different results.
Yogurt is produced using a culture ofLactobacillus delbrueckii subsp.bulgaricus andStreptococcus thermophilus bacteria. Otherlactobacilli andbifidobacteria are sometimes added during or after culturing yogurt. Some countries require yogurt to contain a specific amount ofcolony-forming units (CFU) of bacteria; for example, in China the requirement for the number of lactobacillus bacteria is at least 1 million CFU per milliliter.[3] Some countries also regulate which bacteria can be used: for example, in France,[4] a product can only be labeled as "yaourt" or "yoghourt" if it has been fermented exclusively byLactobacillus delbrueckii subsp. bulgaricus andStreptococcus thermophilus, a requirement that aligns with the international definition of yogurt in theCodex Alimentarius on fermented milk (CXS 243-2003).[5]
The bacterial culture is mixed in, and a warm temperature of 30–45 °C (86–113 °F) is maintained for 4 to 12 hours to allow fermentation to occur, with the higher temperatures working faster but risking a lumpy texture or whey separation.[6][7]
Etymology and spelling
The word for yogurt is derived from theOttoman Turkish:یوغورت,romanized: yoğurt,[8] and is usually related to the verbyoğurmak, "to knead", or "to be curdled or coagulated; to thicken".[8] It may be related toyoğun, meaning thick or dense. The sounds historically represented by the Arabic letterghayn in the Turkish language ranging from avoiced velar fricative to avoiced velar plosive were traditionally romanized as "gh" prior to the introduction of anew Latin-based Turkish alphabet and the letter "ğ" in 1929, thus "yoghurt" spelled with a "gh" is first attested in sources from 1615 to 1625.[8][9][10]
In English, spelling variations includeyogurt,yoghurt, and to a lesser extentyoghourt oryogourt.[8] In the United Kingdom, Australia, New Zealand and South Africa the word is usually spelledyoghurt, while in the United States the spelling isyogurt. Canada has its own spelling,yogourt, a minority variant of the Frenchyaourt, althoughyogurt andyoghurt are also used.[11]
History
Analysis of theL. delbrueckii subsp.bulgaricus genome indicates that the bacterium may have originated on the surface of a plant.[12] Milk may have become spontaneously and unintentionally exposed to it through contact with plants, or bacteria may have been transferred from the udder of domestic milk-producing animals.[13] The origins of yogurt are unknown but it was probably discovered first byNeolithic people inCentral Asia andMesopotamia around 5000 BC, when the first milk-producing animals were domesticated.[14] They most likely found out how toferment milk by chance and in all likelihood, yogurt was discovered independently in this way in many different places at different times.[15][16]
Unstirred TurkishSüzme Yoğurt (strained yogurt), with a 10% fat content
Until the 1900s, yogurt was a staple in diets of people in theRussian Empire (and especially Central Asia and theCaucasus), Western Asia,South Eastern Europe/Balkans, Central Europe, and theIndian subcontinent.Stamen Grigorov (1878–1945), a Bulgarian student of medicine inGeneva, first examined the microflora of the Bulgarian yogurt. In 1905, he described it as consisting of a spherical and a rod-like lactic acid-producing bacteria. In 1907, the rod-like bacterium was calledBacillus bulgaricus (nowLactobacillus delbrueckii subsp.bulgaricus). The Russianbiologist andNobel laureateIlya Mechnikov, from theInstitut Pasteur in Paris, was influenced by Grigorov's work and hypothesized that regular consumption of yogurt was responsible for the unusually long lifespans ofBulgarian peasants.[25] BelievingLactobacillus to be essential for good health, Mechnikov worked to popularize yogurt as a foodstuff throughout Europe.
Industrialization of yogurt production is credited toIsaac Carasso, who, in 1919, started a small yogurt business inBarcelona, Spain, naming the businessDanone ("little Daniel") after his son.[26] The brand later expanded to the United States under an Americanized version of the name,Dannon.[26] Yogurt with added fruitjam was patented in 1933 by the Radlická Mlékárna dairy inPrague.[27]
Yogurt was introduced to the United States in the first decade of the twentieth century, influenced byÉlie Metchnikoff'sThe Prolongation of Life; Optimistic Studies (1908); it was available in tablet form for those with digestive intolerance and for home culturing.[28] It was popularized byJohn Harvey Kellogg at theBattle Creek Sanitarium, where it was used both orally and inenemas,[29] and later byArmenian immigrants Sarkis and Rose Colombosian, who started "Colombo and Sons Creamery" inAndover, Massachusetts, in 1929.[30][31]
Colombo Yogurt was originally delivered around New England in a horse-drawn wagon inscribed with the Armenian word "madzoon" which was later changed to "yogurt", theTurkish language name of the product, as Turkish was thelingua franca between immigrants of the variousNear Eastern ethnicities who were the main consumers at that time. Yogurt's popularity in the United States was enhanced in the 1950s and 1960s, when it was presented as ahealth food by scientists like Hungarian-born bacteriologistStephen A. Gaymont.[32] Plain yogurt still proved too sour for the American palate and in 1966 Colombo Yogurt sweetened the yogurt and added fruit preserves, creating "fruit on the bottom" style yogurt. This was successful and company sales soon exceeded $1 million per year.[33] By the late 20th century, yogurt had become a common American food item and Colombo Yogurt was sold in 1993 toGeneral Mills, which discontinued the brand in 2010.[34]
Yogurt (plain yogurt from whole milk) is 81% water, 9%protein, 5% fat, and 4%carbohydrates, including 4% sugars (table). A 100-gram amount provides 406 kilojoules (97 kcal) of dietary energy. As a proportion of theDaily Value (DV), a serving of yogurt is a rich source ofvitamin B12 (31% DV) andriboflavin (23% DV), with moderate content of protein,phosphorus, andselenium (14 to 19% DV; table).
Comparison of whole milk and plain yogurt from whole milk, one cup (245 g) each
Tilde (~) represents missing or incomplete data.The above shows little difference exists between whole milk and yogurt made from whole milk with respect to the listed nutritional constituents.
A 2011 review stated that high-quality clinical evidence was insufficient to conclude that consuming yogurt lowers the risk of diseases or otherwise improves health.[42]Meta-analyses found that consuming 80 grams per day of low-fat yogurt was associated with a lower risk of developingtype 2 diabetes[41] and a lower incidence ofhip fracture inpost-menopausal women.[43] A 2021 review found acause-and-effect relationship between yogurt consumption and improved lactose tolerance and digestion, and that potential associations exist between yogurt consumption and improving bone health, as well as lowering the risk of some diseases, including cancers andmetabolic syndrome.[44] Daily intake of 50 grams of yogurt has been shown to reduce risk of overweight or obesity by 13%, and reduce risk oftype 2 diabetes by 7%.[45] Yogurt consumption has been associated with reduced risk ofcardiovascular disease,[46][47] andinsulin resistance.[48] Some of the benefits were somewhat better for the lower fat yogurts.[45][47] Many commercial yogurt products are supplemented with extraprobiotic bacteria.[48]
Contamination occurs in traditionally prepared yogurts more often than industrially processed ones, but may affect the latter as well if manufacturing and packaging practices are suboptimal.[50]
When mold forms on yogurt it can not be scraped away. The consistency of yogurt allows the mold to penetrate deeply under the surface where it spreads.[51]
Varieties and presentation
Tzatziki orcacık is ameze made with yogurt, cucumber, olive oil and fresh mint or dill.
Dahi is a yogurt from theIndian subcontinent, known for its characteristic taste and consistency. The worddahi seems to be derived from theSanskrit worddadhi ("sour milk"), one of the five elixirs, orpanchamrita, often used in Hindu ritual. Sweetened dahi (mishti doi ormeethi dahi) is common in eastern parts of India, made by fermenting sweetened milk. While cow's milk is currently the primary ingredient for yogurt, goat and buffalo milk were widely used in the past, and valued for the fat content (seebuffalo curd).
Dadiah or dadih is a traditional WestSumatran yogurt made fromwater buffalo milk, fermented inbamboo tubes.[52] Yogurt is common inNepal, where it is served as both an appetizer and dessert. Locally calleddahi, it is a part of the Nepali culture, used in local festivals, marriage ceremonies, parties, religious occasions, family gatherings, and so on. One Nepalese yogurt is calledjuju dhau, originating from the city ofBhaktapur. InTibet, yak milk (technically dri milk, as the word yak refers to the male animal) is made into yogurt (and butter and cheese) and consumed.
InNorthern Iran,Mâst Chekide is a variety ofkefir yogurt with a distinct sour taste. It is usually mixed with apesto-like water and fresh herb purée calleddelal. Common appetizers arespinach oreggplantborani,Mâst-o-Khiâr with cucumber, spring onions and herbs, andMâst-Musir with wildshallots. In the summertime, yogurt and ice cubes are mixed together with cucumbers,raisins, salt, pepper and onions and topped with some croutons made of Persian traditional bread and served as a cold soup.Ashe-Mâst is a warmyogurt soup with fresh herbs, spinach and lentils. Even the leftover water extracted whenstraining yogurt is cooked to make a sour cream sauce calledkashk, which is usually used as a topping on soups and stews.
Khyar w Laban (cucumber and yogurt salad) is a dish in Lebanon and Syria. Also, a wide variety of local Lebanese and Syrian dishes are cooked with yogurt like "Kibbi bi Laban"Rahmjoghurt, a creamy yogurt with much higher fat content (10%) than many yogurts offered in English-speaking countries.Dovga, a yogurt soup cooked with a variety of herbs and rice, is served warm in winter or refreshingly cold in summer.Jameed, yogurt salted and dried to preserve it, is consumed inJordan.Zabadi is the type of yogurt made in Egypt, usually from the milk of theEgyptian water buffalo. It is particularly associated withRamadan fasting, as it is thought to prevent thirst during all-day fasting.[53]
To offset its naturalsourness, yogurt is also sold sweetened, sweetened and flavored or in containers with fruit or fruit jam on the bottom.[54] The two styles of yogurt commonly found in the grocery store are set-style yogurt and Swiss-style yogurt. Set-style yogurt is poured into individual containers to set, while Swiss-style yogurt is stirred prior to packaging. Either may have fruit added to increase sweetness.[54]
Lassi is a common Indian beverage made from stirred liquified yogurt that is either salted or sweetened with sugar commonly, less commonly honey and combined with fruit pulp to create flavored lassi.[55] Consistency can vary widely, with urban and commercial lassis having uniform texture through being processed, whereas rural and rustic lassi has discernible curds or fruit pulp.[55]
Large amounts of sugar – or othersweeteners for low-energy yogurts – are often used in commercial yogurt.[54][56] Some yogurts contain addedmodified starch,[57]pectin (found naturally in fruit) orgelatin to create thickness and creaminess. This type of yogurt may be marketed under the name Swiss-style, although it is unrelated to conventional Swiss yogurt. Some yogurts, often called "cream line", are made with whole milk which has not been homogenized so the cream rises to the top. In many countries, sweetened, flavored yogurt is common, typically sold insingle-servingplastic cups.[54] Common flavors may includevanilla,honey, andtoffee, and various fruits.[54][56] In the early 21st century, yogurt flavors inspired by desserts, such as chocolate or cheesecake, became common.[56] There is concern about thehealth effects of sweetened yogurt due to its high sugar content,[54] although research indicates that use of sugar in yogurt manufacturing has decreased since 2016 in response toWHO and government initiatives to combatobesity.[54]
A coffee filter used to strain yogurt in a home refrigerator
Strained yogurt has been strained through a filter, traditionally made ofmuslin and more recently of paper or non-muslin cloth. This removes thewhey, giving a much thicker consistency. Strained yogurt is made at home, especially if using skimmed milk which results in a thinner consistency.[58] Yogurt that has been strained to filter or remove the whey is known as labneh in Middle Eastern countries. It has a consistency between that of yogurt and cheese. It may be used forsandwiches in Middle Eastern countries. Olive oil, cucumber slices, olives, and various green herbs may be added. It can be thickened further and rolled into balls, preserved in olive oil, and fermented for a few more weeks. It is sometimes used with onions, meat, and nuts as a stuffing for a variety of pies orkibbeh balls.
Some types of strained yogurts are boiled in open vats first, so that the liquid content is reduced. The East Indian dessert, a variation of traditional dahi calledmishti dahi, offers a thicker, more custard-like consistency, and is usually sweeter than western yogurts.[59] In western Indian (Marathi and Gujarati) cuisine, strained yogurt is macerated with sugar and spices such as saffron, cardamom and nutmeg to make the dessert "shrikhand". Strained yogurt is also enjoyed in Greece and is the main component oftzatziki, a well-known accompaniment togyros andsouvlaki pita sandwiches: it is a yogurt sauce or dip made with the addition of gratedcucumber,olive oil, salt and, optionally, mashed garlic.Srikhand, a dessert in India, is made from strained yogurt,saffron,cardamom,nutmeg and sugar and sometimes fruits such asmango orpineapple.
In North America, strained yogurt is commonly called "Greek yogurt". Powdered milk is sometimes added in lieu of straining to achieve thickness. In Britain, the name "Greek" may only be applied to yogurt made in Greece.[60]
Ayran,doogh ("dawghe" inNeo-Aramaic) or dhallë is a yogurt-based, salty drink. It is made by mixing yogurt with water and (sometimes) salt.
Borhani (or burhani) is a spicy yogurt drink fromBangladesh. It is usually served with kacchibiryani at weddings and special feasts. Key ingredients are yogurt blended with mint leaves (mentha),mustard seeds and black rock salt (Kala Namak). Ground roastedcumin, groundwhite pepper, greenchili pepper paste and sugar are often added.
Lassi is a yogurt-based beverage that is usually slightly salty or sweet, and may be commercially flavored withrosewater,mango or other fruit juice. Salty lassi is usually flavored with ground, roasted cumin andred chilies, and may be made withbuttermilk.[61]
An unsweetened and unsalted yogurt drink usually called simplyjogurt is consumed withburek and other baked goods in theBalkans. Sweetened yogurt drinks are the usual form in Europe (including the UK) and the US, containing fruit and added sweeteners. These are typically called "drinkable yogurt". Also available are "yogurt smoothies", which contain a higher proportion of fruit and are more likesmoothies.[citation needed]
Production
Commercially available home yogurt maker
Yogurt production involves preparing warm milk to a temperature (30–45 °C (86–113 °F)) that will not kill the livemicroorganisms that turn the milk into yogurt, inoculating certain bacteria (starter culture), usuallyStreptococcus thermophilus andLactobacillus bulgaricus, into the milk, and finally keeping it warm for several hours (4–12 hours).[62]
Milk with a higher concentration of solids than normal milk may be used; the higher solids content produces a firmer yogurt. Solids can be increased by adding dried milk.[63] The yogurt-making process provides two significant barriers topathogen growth, heat and acidity (low pH). Both are necessary to ensure a safe product. Acidity alone has been questioned by recent outbreaks of food poisoning byE. coli O157:H7 that is acid-tolerant.E. coli O157:H7 is easily destroyed by pasteurization (heating); the initial heating of the milk kills pathogens as well as denaturing proteins.[64] The microorganisms that turn milk into yogurt can tolerate higher temperatures than most pathogens, so that a suitable temperature not only encourages the formation of yogurt, but inhibits pathogenic microorganisms. Once the yogurt has formed it can, if desired, bestrained to reduce the whey content and thicken it.
Microstructure
Yogurt is characterized as a viscous, shear-thinning,non-Newtonian fluid that forms when milk, aNewtonian fluid, is fermented, causing protein aggregation and subsequentgelation.[65] The result is a soft solid that can be modeled via the interactions of the casein proteins.[66] Themicrostructure of yogurt is affected by both the fat and protein content and the processing conditions of the yogurt. In low-fat formulations, the microstructure is a network of casein protein globules joined via clusters and strands that encapsulate pores: these pores house the aqueous phase and the bacterial cultures of the yogurt.[66][67]
Stirred yogurt formulations have a coarser distribution of loosely associated casein particulates due to theshear forces and resulting particle-particle collisions induced during the mixing process. After stirring, yogurt is more accurately defined as a weak gel.[66]
Rheology
The mechanical properties of yogurt are typically assessed usingrheometry, which quantifies the deformation and flow response of soft materials subject to shear forces. As is central inmaterials science, the rheological properties of yogurt are dictated by a variety of processing factors, including the ratios of dry and wet matter, thermal treatments, milk origin, starter cultures, and yogurt type.[65][68]
Although cow milk is a common choice for yogurt production, other milks, such as goat, sheep, and camel, produce different rheologies. Goat milk yogurt has a low viscosity and a thinner texture when compared to cow milk yogurt.[68] Conversely, sheep milk, having higher content of solids, has a higher viscosity and thicker texture when compared to cow milk yogurt.[68]
Yogurt can further be characterized as "set" versus stirred, wherein set yogurts are processed and sold in the same container, and stirred yogurts are mixed prior to packaging in a secondary container.[65]
Commerce
Yogurts and dairy desserts in a French supermarket in 2007
Pasteurized yogurt ("heat treated fermented milk")[69] is yogurt pasteurized to kill bacteria.[70]
Probiotic yogurt (labeled as "live yogurt" or "active yogurt") is yogurt pasteurized to kill bacteria, withLactobacillus added in measured units before packaging.[dubious –discuss]
Yogurt probiotic drink is a drinkable yogurt pasteurized to kill bacteria, withLactobacillus added before packaging.
Under USFood and Drug Administration regulations, milk must be pasteurizedbefore it is cultured, and may optionally be heat treated after culturing to increase shelf life.[71] Most commercial yogurts in the United States are not heat treated after culturing, and contain live cultures.
Yogurt with live cultures[72][73][74] is more beneficial than pasteurized yogurt for people with lactose malabsorption.[75]
Lactose intolerance
Lactose intolerance is a condition in which people have symptoms due to the decreased ability to digest lactose, a sugar found in dairy products. In 2010, theEuropean Food Safety Authority (EFSA) determined that lactose intolerance can be alleviated by ingesting live yogurt cultures (lactobacilli) that are able to digest the lactose in other dairy products.[75] The scientific review by EFSA enabled yogurt manufacturers to use ahealth claim on product labels, provided that the "yogurt should contain at least 108 CFU live starter microorganisms (Lactobacillus delbrueckii subsp.bulgaricus andStreptococcus thermophilus) per gram. The target population is individuals with lactose maldigestion".[75] A 2021 review found that yogurt consumption could improve lactose tolerance and digestion.[44]
Plant-based products
A variety of plant-based yogurt alternatives appeared in the 2000s, usingsoy milk,rice milk, and nut milks such asalmond milk andcoconut milk fermented with cultures. These products may be suitable for people withlactose intolerance and those who prefer plant-based foods, such as vegetarians andvegans.[76]Plant-based milks have different structures and components thandairy milk. Though they can be used to make many products similar to those made from dairy, there are differences in taste and texture, and some consumers may feel that they lack the "delicate and smooth structure" of "conventional yogurts".[77] Since plant-based milks do not containlactose (the food ofStreptococcus thermophilus andLactobacillus bulgaricus), plant-based products usually contain different bacterial strains than yogurt, such asLactobacillus casei,Lactobacillus rhamnosus, andBifidobacterium bifidum.[78] Plant-based products also vary considerably in their nutrition and ingredients and may contain gums, stabilizers, high-intensity sweeteners, and artificial colors.[78]
Red wood ants have been used in Bulgaria and Turkey to make yogurt; a few ants are added to warm milk and left to ferment. Modern studies suggest that the ants' formic acid acidulates the milk, enabling microbes from the ants' microbes to thrive, and ant or bacterial enzymes break down milk proteins to produce a yogurt.[84][85]
^abcd"Yogurt". Collins English Dictionary – Complete & Unabridged 10th Edition. HarperCollins. 2012. Archived fromthe original on 5 October 2023. Retrieved21 March 2017.
^Dalby A (1996).Siren Feasts: A History of Food and Gastronomy in Greece. London: Routledge. p. 66.ISBN0-415-15657-2.
^Alcock JP (2006).Food in the Ancient World. Greenwood Publishing Group. p. 83.ISBN978-0-313-33003-2.Curdled milk (oxygala or melca), probably a kind of yogurt, was acceptable because it was easier to digest. Even so, it was still to be mixed with honey or olive oil. Columella gave instructions on how to make sour milk with seasoning into ...
^abHoffman S (2004).The Olive and the Caper: Adventures in Greek Cooking. Workman Publishing. p. 471.ISBN978-0-7611-6454-8....something like yogurt was known to Greeks since classical times – a sort of thickened sour milk called Pyriate or oxygala. Oxi meant "sour" or "vinegar"; gala, "milk". Galen says that Oxygala was eaten alone with honey, just as thick Greek yogurt is today.
^abAdamson MW (2008).Entertaining from Ancient Rome to the Super Bowl: An Encyclopedia [2 volumes]: An Encyclopedia. ABC-CLIO. p. 9.ISBN978-0-313-08689-2.Oxygala, however, a form of yogurt, was eaten and sometimes mixed with honey. Ancient Greek and Roman cuisine did not rely on non-cultured milk products, which can be explained in part because without refrigeration milk becomes sour ...
^The Natural History of Pliny, tr.John Bostock,Henry Thomas Riley, London: Bell, 1856–93, Volume 3 (book 11, section 239),p. 84: "It is a remarkable circumstance, that the barbarous nations which subsist on milk have been for so many ages either ignorant of the merits of cheese, or else have totally disregarded it; and yet they understand how to thicken milk and form therefrom an acrid kind of milk with a pleasant flavor, as well as a rich butter".
^abNestel PJ, Mori TA (2022). "Dietary patterns, dietary nutrients and cardiovascular disease".Reviews in Cardiovascular Medicine.23 (1): 17.doi:10.31083/j.rcm2301017.PMID35092209.
^Surono IS (1 January 2015). "Traditional Indonesian dairy foods".Asia Pacific Journal of Clinical Nutrition.24 (Suppl 1):S26 –S30.doi:10.6133/apjcn.2015.24.s1.05.PMID26715081.
^abcBerry D (20 May 2014)."Building a better yogurt". Food Business News, Sosland Publishing.Archived from the original on 23 February 2020. Retrieved8 January 2020.
^Alting AC, Fred Van De Velde, Kanning MW, Burgering M, Mulleners L, Sein A, Buwalda P (2009). "Improved creaminess of low-fat yogurt: The impact of amylomaltase-treated starch domains".Food Hydrocolloids.23 (3):980–987.doi:10.1016/j.foodhyd.2008.07.011.
^Davidson A (2014).The Oxford Companion to Food. Oxford University Press.ISBN978-0-19-104072-6.
^Maisonneuve S, Ouriet MF, Duval-Iflah Y (June 2001). "Comparison of yoghurt, heat treated yoghurt, milk and lactose effects on plasmid dissemination in gnotobiotic mice".Antonie van Leeuwenhoek.79 (2):199–207.doi:10.1023/A:1010246401056.PMID11520006.S2CID11673881.
^"European Court Prohibits Use of Dairy Names for NonDairy Products"(PDF) (PDF). USDAForeign Agricultural Service. 11 July 2017.Archived(PDF) from the original on 16 July 2024. Retrieved29 April 2021.In its June 14 ruling, the ECJ concluded that for marketing and advertising purposes, in principle, the designations "milk", "cream", "butter", "cheese" and "yogurt" are reserved under EU law for products of animal origin only. The ECJ ruling prohibits the use of dairy names in association with purely plantbased products unless the names are included in an EU list of exceptions. The ECJ also clarifies that this prohibition applies even when the plant origin of the product concerned is provided because the addition of descriptive and explanatory terms cannot completely rule out consumer confusion.
^Sinotte, Veronica M.; Ramos-Viana, Verónica; Vásquez, Diego Prado; Sirakova, Sevgi Mutlu; Valerón, Nabila Rodríguez; et al. (3 October 2025). "Making yogurt with the ant holobiont uncovers bacteria, acids, and enzymes for food fermentation".iScience. Elsevier.doi:10.1016/j.isci.2025.113595.ISSN2589-0042.
