Yogurt



Yogurt, yoghurt, or yoghourt ( or ; from yoğurt; other spellings listed below) is a food produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as "yogurt cultures". Fermentation of lactose by these bacteria produces lactic acid, which acts on milk protein to give yogurt its texture and characteristic tart flavor. Cow's milk is commonly available worldwide, and, as such, is the milk most commonly used to make yogurt. Milk from water buffalo, goats, ewes, mares, camels, and yaks is also used to produce yogurt where available locally. Milk used may be homogenized or not (milk distributed in many parts of the world is homogenized); both types may be used, with substantially different results. In North America, yogurt is sold plain, sweetened (with honey, sugar, or sugar substitutes), or sweetened and flavoured with fruit, vanilla, coffee and other flavours.

Yogurt is produced using a culture of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus bacteria. In addition, other lactobacilli and bifidobacteria are also sometimes added during or after culturing yogurt. Some countries require yogurt to contain a certain amount of colony-forming units of bacteria; in China, for example, the requirement for the number of lactobacillus bacteria is at least 1 × 106 CFU per milliliter.

To produce yogurt, milk is first heated, usually to about 85 °C (185 °F), to denature the milk proteins so that they set together rather than form curds. After heating, the milk is allowed to cool to about 45 °C (113 °F). The bacterial culture is mixed in, and a temperature of 45 °C (113 °F) is maintained for four to twelve hours to allow fermentation.

Etymology and spelling
The word is derived from yoğurt, and is usually related to the verb yoğurmak, "to knead", or "to be curdled or coagulated; to thicken". It may be related to yoğun, meaning thick or dense. The sound ğ was traditionally rendered as "gh" in transliterations of Turkish from around 1615-1625. In English, there are several variations of the spelling of the word, including yogurt, and yoghurt and to a lesser extent yoghourt or yogourt.

History
Analysis of the L. delbrueckii subsp. bulgaricus genome indicates that the bacterium may have originated on the surface of a plant. 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. The origins of yogurt are unknown, but it is thought to have been invented in Mesopotamia around 5000 BC. In ancient Indian records, the combination of yogurt and honey is called "the food of the gods". Persian traditions hold that "Abraham owed his fecundity and longevity to the regular ingestion of yogurt".

The cuisine of ancient Greece included a dairy product known as oxygala (οξύγαλα) which is believed to have been a form of yogurt. Galen (AD 129 – c. 200/c. 216) mentioned that oxygala was consumed with honey, similar to the way thickened Greek yogurt is eaten today. 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". The use of yogurt by medieval Turks is recorded in the books Diwan Lughat al-Turk by Mahmud Kashgari and Kutadgu Bilig by Yusuf Has Hajib written in the 11th century. Both texts mention the word "yogurt" in different sections and describe its use by nomadic Turks. The earliest yogurts were probably spontaneously fermented by wild bacteria in goat skin bags.

Some accounts suggest that Indian emperor Akbar's cooks would flavor yogurt with mustard seeds and cinnamon. Another early account of a European encounter with yogurt occurs in French clinical history: Francis I suffered from a severe diarrhea which no French doctor could cure. His ally Suleiman the Magnificent sent a doctor, who allegedly cured the patient with yogurt. Being grateful, the French king spread around the information about the food which had cured him.

Until the 1900s, yogurt was a staple in diets of people in the Russian Empire (and especially Central Asia and the Caucasus), Western Asia, South Eastern Europe/Balkans, Central Europe, and India. Stamen Grigorov (1878–1945), a Bulgarian student of medicine in Geneva, 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 called Bacillus bulgaricus (now Lactobacillus delbrueckii subsp. bulgaricus). The Russian Nobel laureate and biologist Ilya Ilyich Mechnikov (also known as Élie Metchnikoff), 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. Believing Lactobacillus to be essential for good health, Mechnikov worked to popularize yogurt as a foodstuff throughout Europe.

Isaac Carasso industrialized the production of yogurt. In 1919, Carasso, who was from Ottoman Salonika, started a small yogurt business in Barcelona, Spain, and named the business Danone ("little Daniel") after his son. The brand later expanded to the United States under an Americanized version of the name: Dannon. Yogurt with added fruit jam was patented in 1933 by the Radlická Mlékárna dairy in Prague.

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. It was popularized by John Harvey Kellogg at the Battle Creek Sanitarium, where it was used both orally and in enemas, and later by Armenian immigrants Sarkis and Rose Colombosian, who started "Colombo and Sons Creamery" in Andover, Massachusetts in 1929. 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", the Turkish name of the product, as Turkish was the lingua franca between immigrants of the various Near 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 a health food. By the late 20th century, yogurt had become a common American food item and Colombo Yogurt was sold in 1993 to General Mills, which discontinued the brand in 2010.

Nutrition and health
In a 100-gram amount providing 406 kJ of dietary energy, yogurt (plain Greek yogurt from whole milk) is 81% water, 9% protein, 5% fat and 4% carbohydrates, including 4% sugars (table). As a proportion of the Daily Value (DV), a serving of yogurt is a rich source of vitamin B12 (31% DV) and riboflavin (23% DV), with moderate content of protein, phosphorus and selenium (14 to 19% DV; table).

Tilde (~) represents missing or incomplete data. −	The above shows that there is little difference between whole milk and yogurt made from whole milk with respect to the listed nutritional constituents. The differences may be explained as a result of testing the product after draining liquid whey from the yogurt thereby changing the percentage of that constituent in the final product.

Although yogurt is often associated with probiotics having positive effects on immune, cardiovascular or metabolic health, there is insufficient high-quality clinical evidence to conclude that consuming yogurt lowers risk of diseases or improves health.

The United Kingdom and the United States recommend different maximum amounts of daily sugar intake but in both nations many sweetened yogurts have too much. "A 150g (5oz) serving of some 0% fat yogurts can contain as much as 20g (0.7oz) of sugar – the equivalent of five teaspoons, says Action on Sugar – which is about 40% of a woman's daily recommended intake of added sugar (50g or 1.7oz) and about 30% of that for men (70g or 2.5oz)."

"The American Heart Association recommends that men eat no more than 36 grams of sugar per day, and women no more than 20. Many of the top-selling yogurts have even more than the 19 grams of sugar that is contained in a Twinkie." Consumers wanting sweetened yogurt are advised to choose yogurt sweetened with sugar substitute and check the contents list to avoid corn syrup, high fructose corn syrup, honey, or sugar.

Varieties and presentation
Da-hi is a yogurt of the Indian subcontinent, known for its characteristic taste and consistency. The word da-hi seems to be derived from the Sanskrit word dadhi, one of the five elixirs, or panchamrita, often used in Hindu ritual. Dahi also holds cultural symbolism in many homes in the Mithila region of Nepal and Bihar. Yogurt balances the palate across regional cuisines throughout India. In the hot and humid south, yogurt and foods made of yogurt are a staple in order to cool down – yogurt rice is always the last dish of the meal. Also, the vegetarian population of India derives some protein from yogurt (other than lentil and beans). Sweet yogurt (meesti doi or meethi dahi) is common in eastern parts of India, made by fermenting sweetened milk. While cow's milk is considered sacred and is currently the primary ingredient for yogurt, goat and buffalo milk were widely used in the past, and valued for the fat content (see buffalo curd). Butter and cream were made by churning the yogurt/milk.

In India and Pakistan, it is often used in cosmetics mixed with turmeric and honey. Sour yogurt, is also used as a hair conditioner by women in many parts of India and Pakistan. Dahi is also known as Mosaru (Kannada), Thayir (Tamil/Malayalam), doi (Assamese, Bengali), dohi (Odia), perugu (Telugu), Qәzana a pәәner (Pashto) and Dhahi or Dhaunro. Raita is a yogurt-based South Asian/Indian condiment, used as a side dish. The yogurt is seasoned with coriander (cilantro), cumin, mint, cayenne pepper, and other herbs and spices. Vegetables such as cucumber and onions are mixed in, and the mixture is served chilled. Raita has a cooling effect on the palate which makes it a good foil for spicy Indian and Pakistani dishes. Raita is sometimes also referred to as dahi.

Dadiah or dadih is a traditional West Sumatran yogurt made from water buffalo milk, fermented in bamboo tubes. Yogurt is popular in Nepal, where it is served as both an appetizer and dessert. Locally called dahi, it is a part of the Nepali culture, used in local festivals, marriage ceremonies, parties, religious occasions, family gatherings, and so on. The most famous type of Nepalese yogurt is called juju dhau, originating from the city of Bhaktapur. In Tibet, yak milk (technically dri milk, as the word yak refers to the male animal) is made into yogurt (and butter and cheese) and consumed.

In Northern Iran, Mâst Chekide is a variety of kefir yogurt with a distinct sour taste. It is usually mixed with a pesto-like water and fresh herb purée called delal. Yogurt is a side dish to all Iranian meals. The most popular 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. Ashe-Mâst is a warm yogurt soup with fresh herbs, spinach and lentils. 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.

Matsoni is a Georgian yogurt popular in the Caucasus and Russia. It is used in a wide variety of Georgian dishes and is believed to have contributed to the high life expectancy and longevity in the country. Dannon used this theory in their 1978 TV advertisement called In Soviet Georgia where shots of elderly Georgian farmers were interspersed with an off-camera announcer intoning, "In Soviet Georgia, where they eat a lot of yogurt, a lot of people live past 100." Matsoni is also popular in Japan under the name Caspian Sea Yogurt.

Tarator and Cacık are popular cold soups made from yogurt, popular during summertime in Albania, Azerbaijan (known as Dogramac), Bulgaria, Macedonia, Serbia and Turkey. They are made with ayran, cucumbers, dill, salt, olive oil, and optionally garlic and ground walnuts. Tzatziki in Greece and milk salad in Bulgaria are thick yogurt-based salads similar to tarator.

Khyar w Laban (cucumber and yogurt salad) is a popular dish in Lebanon and Syria. Also, a wide variety of local Lebanese and Syrian dishes are cooked with yogurt like "Kibbi bi Laban", etc. Rahmjoghurt, a creamy yogurt with much higher fat content (10%) than many yogurts offered in English-speaking countries (Rahm is German for "cream"), is available in Germany and other countries. Dovga, a yogurt soup cooked with a variety of herbs and rice is popular in Azerbaijan, often served warm in winter or refreshingly cold in summer. Yogurt made with unhomogenized milk is sometimes called cream-top yogurt; a layer of cream rises to the top. Jameed is yogurt which is salted and dried to preserve it. It is popular in Jordan. Zabadi is the type of yogurt made in Egypt, usually from the milk of the Egyptian water buffalo. It is particularly associated with Ramadan fasting, as it is thought to prevent thirst during all-day fasting.

Sweetened and flavored
To offset its natural sourness, yogurt is also sold sweetened, sweetened and flavored or in containers with fruit or fruit jam on the bottom. The two styles of yogurt commonly found in the grocery store are set type yogurt and Swiss style yogurt. Set type yogurt is when the yogurt is packaged with the fruit on the bottom of the cup and the yogurt on top. Swiss style yogurt is when the fruit is blended into the yogurt prior to packaging.

Lassi and moru are common beverages in India. Lassi is stirred liquified curd that is either salted or sweetened with sugar commonly, less commonly honey and often combined with fruit pulp to create flavored lassi. Mango lassi is a western favorite, as is coconut lassi. Consistency can vary widely, with urban and commercial lassis being of uniform texture through being processed, whereas rural and rustic lassi has curds in it, and sometimes has malai (cream) added or removed. Moru is a popular South Indian summer drink, meant to keep drinkers hydrated through the hot and humid summers of the South. It is prepared by considerably thinning down yogurt with water, adding salt (for electrolyte balance) and spices, usually green chili peppers, asafoetida, curry leaves and mustard.

Large amounts of sugar – or other sweeteners for low-energy yogurts – are often used in commercial yogurt. Some yogurts contain added modified starch, pectin (found naturally in fruit), and/or gelatin to create thickness and creaminess artificially at lower cost. This type of yogurt is also marketed under the name Swiss-style, although it is unrelated to the way yogurt is eaten in Switzerland. Some yogurts, often called "cream line", are made with whole milk which has not been homogenized so the cream rises to the top. In the UK, Ireland, France and United States, sweetened, flavored yogurt is the most popular type, typically sold in single-serving plastic cups. Common flavors include vanilla, honey, and toffee, and fruit such as strawberry, cherry, blueberry, blackberry, raspberry, mango and peach. In the early twenty-first century yogurt flavors inspired by desserts, such as chocolate or cheesecake, have been available. There is concern about the health effects of sweetened yogurt, due to its high sugar content.

Straining
Strained yogurt has been strained through a filter, traditionally made of muslin and more recently of paper or cloth. This removes the whey, giving a much thicker consistency and a distinctive slightly tangy taste. Strained yogurt is becoming more popular with those who make yogurt at home, especially if using skimmed milk which results in a thinner consistency. 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 is popular for sandwiches 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 or kibbeh balls.

Some types of strained yogurts are boiled in open vats first, so that the liquid content is reduced. The popular East Indian dessert, a variation of traditional dahi called mishti dahi, offers a thicker, more custard-like consistency, and is usually sweeter than western yogurts. Strained yogurt is also enjoyed in Greece and is the main component of tzatziki (from Turkish "cacık"), a well-known accompaniment to gyros and souvlaki pita sandwiches: it is a yogurt sauce or dip made with the addition of grated cucumber, olive oil, salt and, optionally, mashed garlic. Srikhand, a popular dessert in India, is made from strained yogurt, saffron, cardamom, nutmeg and sugar and sometimes fruits such as mango or pineapple.

In North America and Britain, strained yogurt is commonly called “Greek yogurt”. Strained yogurt is sometimes marketed in North America as "Greek yogurt" and in Britain as "Greek-style yoghurt". In Britain the name "Greek" may only be applied to yogurt made in Greece.

Beverages


Doogh ("dawghe" in Neo-Aramaic), ayran or dhallë is a yogurt-based, salty drink popular in Iran, Albania, Bulgaria, Turkey, Azerbaijan, Afghanistan, Pakistan, Bangladesh, Macedonia, Uzbekistan, Kazakhstan and Kyrgyzstan. It is made by mixing yogurt with water and (sometimes) salt. The same drink is known tan in Armenia; laban ayran in Syria and Lebanon; shenina in Iraq and Jordan; laban arbil in Iraq; majjiga (Telugu), majjige (Kannada), and moru (Tamil and Malayalam) in South India; namkeen lassi in Punjab and all over Pakistan.

Borhani (or Burhani) is a spicy yogurt drink popular in Bangladesh and parts of Bengal. It is usually served with kacchi biryani at weddings and special feasts. Key ingredients are yogurt blended with mint leaves (mentha), mustard seeds and black rock salt (Kala Namak). Ground roasted cumin, ground white pepper, green chili pepper paste and sugar are often added. Lassi is a yogurt-based beverage originally from the Indian subcontinent that is usually slightly salty or sweet. Lassi is a staple in Punjab. In some parts of the subcontinent, the sweet version may be commercially flavored with rosewater, mango or other fruit juice to create a very different drink. Salty lassi is usually flavored with ground, roasted cumin and red chilies; this salty variation may also use buttermilk, and in India is interchangeably called ghol (Bengal), mattha (North India), "majjige" (Karnataka), majjiga (Telangana & Andhra Pradesh), moru (Tamil Nadu and Kerala), Dahi paani Chalha (Odisha), tak (Maharashtra), or chaas (Gujarat). Lassi is very widely drunk in India, Pakistan, and Bangladesh. Mango Lassi is a popular drink at Indian restaurants in US.

In Bosnia and Herzegovina, Croatia, Macedonia, Montenegro, Serbia, and Slovenia, an unsweetened and unsalted yogurt drink usually called simply jogurt is a popular accompaniment to burek and other baked goods. 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 like smoothies. In Ecuador, yogurt smoothies flavored with native fruit are served with pan de yuca as a common type of fast food. In Turkey, yogurt soup or Yayla Çorbası is a popular way of consuming yogurt. The soup is a mix of yogurt, rice, flour and dried mint.

Plant-milk yogurt


A variety of plant-milk yogurts appeared in the 2000s, using soy milk, rice milk, and nut milks such as almond milk and coconut milk. So far the most widely sold variety of plant milk yogurts is soy yogurt. These yogurts are suitable for vegans, people with intolerance to dairy milk, and those who prefer plant milks.

Homemade
Yogurt is made by heating milk to a temperature that denaturates its proteins (scalding), essential for making yogurt, cooling it to a temperature that will not kill the live microorganisms that turn the milk into yogurt, inoculating certain bacteria (starter culture), usually Streptococcus thermophilus and Lactobacillus bulgaricus, into the milk, and finally keeping it warm for several hours. The milk may be held at 85 C for a few minutes, or boiled (giving a somewhat different result). It must be cooled to 50 C or somewhat less, typically 40 - 46 C. Starter culture must then be mixed in well, and the mixture must be kept undisturbed and warm for several hours, ranging from 5 to 12, with longer fermentation producing a more acid yogurt. The starter culture may be a small amount of live yogurt; dried starter culture is available commercially.

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. The yogurt-making process provides two significant barriers to pathogen 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 by E. 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. 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, be strained to reduce the whey content and thicken it.

Other fermented dairy products

 * Amasi
 * Chal
 * Crème fraîche
 * Curd
 * Filmjölk
 * Kumis
 * Quark
 * Ryazhenka
 * Shanklish
 * Smetana
 * Sour cream
 * Varenets
 * Viili