Yogurt (UK: /ˈjɒɡət/; US: /ˈjoʊɡərt/,[1] from Ottoman Turkish: یوغورت, romanized: yoğurt;[a] also spelled yoghurt, yogourt or yoghourt) is a food produced by bacterial fermentation of milk.

[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 by Lactobacillus delbrueckii subsp.

bulgaricus and Streptococcus thermophilus, a requirement that aligns with the international definition of yogurt in the Codex Alimentarius on fermented milk (CXS 243-2003.

[6][7] The word for yogurt is derived from the Ottoman Turkish: یوغورت, romanized: yoğurt,[8] and is usually related to the verb yoğurmak, "to knead", or "to be curdled or coagulated; to thicken".

The sounds historically represented by the Arabic letter ghayn in the Turkish language ranging from a voiced velar fricative to a voiced velar plosive were traditionally romanized as "gh" prior to the introduction of a new 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.

[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 by Neolithic people in Central Asia and Mesopotamia around 5000 BC, when the first milk-producing animals were domesticated.

[20][19] The oldest writings mentioning yogurt are attributed to Pliny the Elder, who remarked that certain "barbarous nations" knew how "to thicken the milk into a substance with an agreeable acidity".

[21] The use of yogurt by medieval Turks is recorded in the books Dīwān Lughāt al-Turk by Mahmud Kashgari and Kutadgu Bilig by Yusuf Has Hajib written in the 11th century.

[24] Some accounts suggest that Mughal Indian emperor Akbar's cooks would flavor yogurt with mustard seeds and cinnamon.

The Russian biologist and Nobel laureate Ilya Mechnikov, from the Institut Pasteur in Paris, was influenced by Grigorov's work and hypothesized that regular consumption of yogurt was responsible for the unusually long lifespans of Bulgarian peasants.

[29] Yogurt was introduced to the United States in the first decade of the twentieth century, influenced by Élie Metchnikoff's The Prolongation of Life; Optimistic Studies (1908); it was available in tablet form for those with digestive intolerance and for home culturing.

[30] It was popularized by John Harvey Kellogg at the Battle Creek Sanitarium, where it was used both orally and in enemas,[31] and later by Armenian immigrants Sarkis and Rose Colombosian, who started "Colombo and Sons Creamery" in Andover, Massachusetts, in 1929.

Yogurt's popularity in the United States was enhanced in the 1950s and 1960s, when it was presented as a health food by scientists like Hungarian-born bacteriologist Stephen A.

Because it may contain live cultures, yogurt is often associated with probiotics, which have been postulated as having positive effects on immune, cardiovascular or metabolic health.

[41][42][43] As of the early 21st century, high-quality clinical evidence was insufficient to conclude that consuming yogurt lowers the risk of diseases or otherwise improves health.

[46] Yogurt made with raw milk can be contaminated with bacteria that can cause significant illness and even result in death, including Listeria, Cryptosporidium, Campylobacter, Brucella, Escherichia coli and Salmonella.

Dadiah or dadih is a traditional West Sumatran yogurt made from water buffalo milk, fermented in bamboo tubes.

Common appetizers are spinach or eggplant borani, Mâst-o-Khiâr with cucumber, spring onions and herbs, and Mâst-Musir with wild shallots.

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.

Even the leftover water extracted when straining yogurt is cooked to make a sour cream sauce called kashk, which is usually used as a topping on soups and stews.

Dovga, a yogurt soup cooked with a variety of herbs and rice, is served warm in winter or refreshingly cold in summer.

[52][54] Some yogurts contain added modified starch,[55] pectin (found naturally in fruit) or gelatin to create thickness and creaminess.

[58] 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".

Srikhand, a dessert in India, is made from strained yogurt, saffron, cardamom, nutmeg and sugar and sometimes fruits such as mango or pineapple.

Key ingredients are yogurt blended with mint leaves (mentha), mustard seeds and black rock salt (Kala Namak).

Lassi is a yogurt-based beverage that is usually slightly salty or sweet, and may be commercially flavored with rosewater, mango or other fruit juice.

[60] An unsweetened and unsalted yogurt drink usually called simply jogurt is consumed with burek and other baked goods in the Balkans.

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".

[73] Plant-based products also vary considerably in their nutrition and ingredients and may contain gums, stabilizers, high-intensity sweeteners, and artificial colors.