Yogurt

• 1. Introduction

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  Yogurt begins with a quiet act of decay. Bacteria ferment the sugars in milk and produce lactic acid. That acid works on milk protein, and the result is a food with a thick texture and a sharp, tart flavor. Cow's milk is the usual starting point. But milk from water buffalo, goats, ewes, mares, camels, and yaks can all be turned into yogurt too. The transformation is driven mainly by two organisms with cumbersome names: Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. Mix in the culture, hold the milk somewhere between 30 and 45 degrees Celsius, and wait. In four to twelve hours, liquid becomes a soft solid. How did Neolithic herders stumble onto this? Why did a Bulgarian medical student in Geneva matter to it? And how did a word from before the year 1000 end up on plastic cups across the world? The answers stretch from ancient Mesopotamia to a horse-drawn wagon in New England, and even to a jar of red wood ants.

• 2. A Word From Old Turkic

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  Yuġrut is the oldest known ancestor of the word. It appears in Uyghur texts from before the year 1000, written in Old Turkic. The term is usually tied to the verb yoğurmak, meaning to knead, or to be curdled, coagulated, or thickened. It surfaces again in Kashgari's Dīwān Lughāt al-Turk, compiled between 1072 and 1074, and was recorded later in 1615 to 1625. English never settled on a single spelling. In the United Kingdom, Australia, New Zealand, and South Africa, people usually write yoghurt. In the United States it is yogurt. Canada keeps its own form, yogourt, a minority variant of the French yaourt, though yogurt and yoghurt appear there too. France went further than spelling. A product can only be labeled yaourt or yoghourt there if it was fermented exclusively by the two defining bacteria, a rule that matches the international definition set out in the Codex Alimentarius standard CXS 243-2003.

• 3. From Mesopotamia To Pliny

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  Around 5000 BC, the first milk-producing animals were domesticated in Central Asia and Mesopotamia, and yogurt was probably discovered there by chance. Neolithic people most likely found out how to ferment milk without trying, and the same accident probably happened independently in many places at different times. The earliest yogurts were likely fermented by wild bacteria inside goat skin bags. Genetic analysis of the L. delbrueckii subsp. bulgaricus genome suggests the bacteria may have started life on the surface of a plant, reaching milk through contact with plants or transferred from an animal's udder. Ancient Greece had its own version, a dairy product called oxygala. Galen, who lived from AD 129 to roughly 200 or 216, noted that oxygala was eaten with honey, much the way thick Greek yogurt is eaten now. The oldest writings on the subject are credited to Pliny the Elder, who observed that certain barbarous nations knew how to thicken milk into a substance with an agreeable acidity. Medieval Turkish use is recorded in two 11th-century books, the Dīwān Lughāt al-Turk by Mahmud Kashgari and the Kutadgu Bilig by Yusuf Has Hajib, both describing nomadic Turks and their yogurt.

• 4. The Bulgarian Bacillus

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  Stamen Grigorov, born in 1878 and a Bulgarian student of medicine in Geneva, was the first to examine the microflora of Bulgarian yogurt. In 1905 he described it as a spherical bacterium paired with a rod-like, lactic acid-producing one. By 1907 the rod was named Bacillus bulgaricus, now known as Lactobacillus delbrueckii subsp. bulgaricus. His work caught the attention of Ilya Mechnikov, the Russian biologist and Nobel laureate at the Institut Pasteur in Paris. Mechnikov hypothesized that regular yogurt eating explained the unusually long lives of Bulgarian peasants. Convinced Lactobacillus was essential to good health, he set out to popularize yogurt across Europe. Until the 1900s it was already a staple from the Russian Empire and the Caucasus through Western Asia, the Balkans, Central Europe, and the Indian subcontinent. Grigorov, who died in 1945, had given a name to something herders had eaten for thousands of years.

• 5. Madzoon To Million-Dollar Brand

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  Isaac Carasso started a small yogurt business in Barcelona, Spain, in 1919, and named it Danone, meaning little Daniel, after his son. The brand later crossed to the United States as Dannon. In 1933 the Radlická Mlékárna dairy in Prague patented yogurt with added fruit jam. Yogurt reached the United States in the first decade of the twentieth century, helped along by Élie Metchnikoff's 1908 book The Prolongation of Life; Optimistic Studies. Early on it was sold in tablet form, for people with digestive intolerance and for culturing at home. John Harvey Kellogg promoted it at the Battle Creek Sanitarium, using it both orally and in enemas. Then came the Armenian immigrants Sarkis and Rose Colombosian, who founded Colombo and Sons Creamery in Andover, Massachusetts, in 1929. Their yogurt was reportedly first delivered around New England in a horse-drawn wagon bearing the Armenian word madzoon, later swapped for the more familiar yogurt. In the 1950s and 1960s, scientists such as the Hungarian-born bacteriologist Stephen A. Gaymont presented it as a health food. Plain yogurt was still too sour for American tastes, so in 1966 Colombo sweetened it and added fruit preserves, inventing fruit on the bottom yogurt. Sales soon passed one million dollars a year. Colombo was sold to General Mills in 1993, and the brand was discontinued in 2010.

• 6. Numbers And The Body

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  Plain yogurt from whole milk is 81 percent water, 9 percent protein, 5 percent fat, and 4 percent carbohydrates, including 4 percent sugars. A 100-gram portion delivers 406 kilojoules of energy. A serving is a rich source of vitamin B12 at 31 percent of the Daily Value and riboflavin at 23 percent, with moderate amounts of protein, phosphorus, and selenium. Compared cup for cup, whole milk and whole-milk yogurt differ very little in their listed nutrients. The health claims are more cautious than the marketing suggests. A 2011 review found high-quality clinical evidence insufficient to say yogurt lowers disease risk or improves health. Meta-analyses linked 80 grams a day of low-fat yogurt to lower risk of type 2 diabetes and fewer hip fractures in post-menopausal women. A 2021 review found a cause-and-effect link to improved lactose tolerance and digestion, and possible ties to bone health and lower risk of some cancers and metabolic syndrome. Daily intake of 50 grams has been shown to cut the risk of overweight or obesity by 13 percent and type 2 diabetes by 7 percent. In 2010 the European Food Safety Authority determined that live yogurt cultures can ease lactose intolerance, allowing a health claim where the yogurt contains at least 100 million colony-forming units of live starter microorganisms per gram.

• 7. Hazards In The Culture

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  Raw-milk yogurt carries real danger. It can be contaminated with bacteria that cause serious illness and even death, including Listeria, Cryptosporidium, Campylobacter, Brucella, Escherichia coli, and Salmonella. Aflatoxin-producing molds such as Aspergillus flavus, Aspergillus parasiticus, and Aspergillus nomius can grow in it as well. Contamination strikes traditionally made yogurts more often than industrial ones, though poor manufacturing and packaging can spoil the latter too. When mold appears on yogurt, it cannot simply be scraped off. The soft consistency lets the mold reach deep below the surface and spread. The yogurt-making process fights pathogens with two barriers, heat and acidity, and both are needed for a safe product. Acidity alone has proven unreliable against acid-tolerant strains like E. coli O157:H7, which is easily destroyed by pasteurization. Heating the milk kills pathogens and denatures proteins, while the yogurt microbes tolerate higher temperatures than most pathogens do. Under US Food and Drug Administration rules, milk must be pasteurized before culturing, though most commercial American yogurts skip heat treatment afterward and keep their live cultures.

• 8. A World Of Variations

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  Dahi is the yogurt of the Indian subcontinent, its name traced to the Sanskrit dadhi, meaning sour milk, one of the five elixirs or panchamrita used in Hindu ritual. Sweetened dahi, called mishti doi or meethi dahi, is common in eastern India, while mishti dahi offers a thicker, custard-like texture. In western Indian cuisine, strained yogurt is macerated with sugar, saffron, cardamom, and nutmeg to make the dessert shrikhand. Bogurar doi is a sweetened yogurt from Bogura, Bangladesh, recognized as a geographical indication product there. Dadiah, or dadih, is a West Sumatran yogurt made from water buffalo milk and fermented in bamboo tubes. In Nepal, yogurt called dahi appears at festivals, weddings, and religious gatherings, and the city of Bhaktapur is known for one called juju dhau. In Tibet, yak milk, technically dri milk, becomes yogurt. Northern Iran has mâst chekide, a sour kefir yogurt mixed with a herb purée called delal. Matzoon is the Armenian yogurt of the Caucasus and Russia. Cold soups like tarator and cacık are made with ayran, cucumbers, dill, salt, olive oil, and sometimes garlic and walnuts, while Greece has tzatziki and Bulgaria its milk salad. Jordan eats jameed, yogurt salted and dried to preserve it. Egypt's zabadi, often made from water buffalo milk, is tied to Ramadan, believed to ward off thirst during a day of fasting. Strained yogurt, with the whey filtered out, is called labneh in the Middle East, sitting somewhere between yogurt and cheese, and is known as Greek yogurt in North America.

  Ayran, doogh, or dhallë is a salty yogurt drink made by mixing yogurt with water and sometimes salt. Borhani, a spicy yogurt drink from Bangladesh, blends yogurt with mint, mustard seeds, and black rock salt, and is served with kacchi biryani at weddings. Lassi, the Indian beverage of stirred liquified yogurt, can be salty or sweet and flavored with rosewater, mango, or other fruit. In the 2000s, plant-based alternatives arrived, using soy, rice, almond, and coconut milk. Because these milks lack lactose, the food of the standard yogurt bacteria, they rely on different strains such as Lactobacillus casei, Lactobacillus rhamnosus, and Bifidobacterium bifidum. The word itself is now contested. In Europe, companies may not call plant-based products yogurt, since EU regulation 1308/2013 and a 2017 Court of Justice ruling reserve the term for products of animal origin. The strangest method of all comes from Bulgaria and Turkey, where red wood ants have been dropped into warm milk and left to ferment. Modern studies suggest the ants' formic acid acidifies the milk, letting microbes from the ants' microbiomes thrive, while ant or bacterial enzymes break down the milk proteins into yogurt.