Yogurt

Yogurt is a tasty and healthy food made by mixing special bacteria with milk and letting it ferment. This process turns the milk into a thicker, tangy treat. While most yogurt comes from cow’s milk, you can also make it from the milk of water buffalo, goats, ewes, mares, camels, and yaks.

The main bacteria used to make yogurt are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus. Sometimes, other helpful bacteria are added too. Different countries have rules about how many bacteria must be in yogurt and which kinds are allowed. For example, in China, yogurt must have at least 1 million bacteria per milliliter, and in France, only certain bacteria can be used to call a product “yogurt.”

To make yogurt, the bacteria are mixed into the milk, and it is kept warm between 30–45 °C (86–113 °F) for 4 to 12 hours. This warmth helps the bacteria work and turn the milk into yogurt. If the temperature is too high, the yogurt might become lumpy or separate into whey.

Etymology and spelling

The word for yogurt comes from Ottoman Turkish, where it was written as یوغورت and pronounced yoğurt. This word is linked to the verb yoğurmak, meaning "to knead" or "to thicken". Even earlier, a similar word, yuġrut, appeared in old Uyghur texts before the year 1000.

In English, yogurt can be spelled in a few ways: yogurt, yoghurt, yoghourt, or yogourt. In places like the United Kingdom, Australia, New Zealand, and South Africa, people usually say yoghurt. In the United States, the common spelling is yogurt. Canada uses the spelling yogourt, which comes from the French word yaourt, but yogurt and yoghurt are also used there.

History

The bacteria used to make yogurt might have first lived on plants. People might have discovered yogurt when milk from animals like cows mixed with these bacteria by accident. It was probably found first by people in Central Asia and Mesopotamia around 5000 BC, when they began to keep animals that gave milk.

In ancient Greece, people made a type of yogurt called oxygala. Writers like Pliny the Elder wrote about how some groups thickened milk to make a tasty, sour food. Later, Turks also used yogurt, writing about it in books from the 11th century. For many years, yogurt was a common food for people in places like the Russian Empire, South Eastern Europe, and the Indian subcontinent.

In the early 1900s, a student named Stamen Grigorov studied Bulgarian yogurt and discovered the special bacteria in it. Another scientist, Ilya Mechnikov, thought that eating yogurt helped people live longer.

Yogurt began to be made on a large scale by a man named Isaac Carasso in Barcelona, Spain, in 1919. He started a company called Danone. Yogurt became popular in the United States in the early 1900s and was made sweeter with fruit, which helped it become a favorite food for many people.

Nutrition

Yogurt made from whole milk is mostly water — about 81% — and also contains protein, fat, and carbohydrates, including sugars. A 100-gram serving gives about 97 kilocalories of energy.

Yogurt is a good source of vitamin B₁₂ and riboflavin, and it also has protein, phosphorus, and selenium.

Health research

Yogurt may help keep us healthy because it can contain live cultures, which some believe support our bodies. Studies have looked at whether eating yogurt can prevent certain illnesses.

Research shows that eating yogurt might help women after menopause avoid breaking their hips and could make it easier to digest milk. It may also support strong bones and possibly lower the chance of some diseases. Eating yogurt regularly might also help prevent weight gain and type 2 diabetes, and support heart health. Many yogurts also have extra helpful bacteria added to them.

Safety

Yogurt made with raw milk can contain harmful bacteria like Listeria, Cryptosporidium, Campylobacter, Brucella, Escherichia coli, and Salmonella. These can make people very sick.

Sometimes, yogurt can also have harmful mold inside. If mold appears on yogurt, it cannot be removed safely because the mold can spread deep inside the yogurt.

Varieties and presentation

Different ways to turn milk into yogurt exist around the world.

Dahi is a type of yogurt from the Indian subcontinent. It comes from an old word in Sanskrit, meaning "sour milk". Sweetened dahi, called mishti doi or meethi dahi, is popular in eastern India and is made by fermenting milk with sugar. While cow's milk is most often used for yogurt today, goat and buffalo milk were also used in the past for their extra fat (see buffalo curd).

Bogurar doi is a special sweet yogurt from Bogura, Bangladesh. It is a famous local food and is officially recognized as a special product of Bangladesh.

Dadiah or dadih is a traditional yogurt from West Sumatra, made from water buffalo milk and fermented in bamboo tubes. Yogurt is common in Nepal, where it is served as both a starter and a dessert. In Tibet, yogurt is made from yak milk.

In Northern Iran, mâst chekide is a type of kefir yogurt with a sour taste. It is often mixed with a green herb mix called delal. Common dishes include spinach or eggplant borani and wild shallots.

Matzoon is an Armenian yogurt found in the Caucasus and Russia. Cold soups like Tarator and cacık are made from yogurt in eastern Europe. These soups include ingredients like ayran, cucumbers, dill, salt, olive oil, and sometimes garlic and walnuts. Tzatziki in Greece and milk salad in Bulgaria are thick yogurt dishes similar to tarator.

Khyar w laban (cucumber and yogurt salad) is a dish from Lebanon and Syria. Many dishes in these countries use yogurt, like "kibbi bi laban". Dovga, a warm or cold yogurt soup with herbs and rice, is enjoyed in winter and summer. Jameed, a salted and dried yogurt, is eaten in Jordan. Zabadi is the main type of yogurt in Egypt, made from the milk of the Egyptian water buffalo. It is especially linked with Ramadan because it helps prevent thirst during long days without eating.

Sweetened and flavored

To make yogurt less sour, it is often sold sweetened, with added flavors, or with fruit or jam at the bottom of the container. The two common types found in stores are set-style yogurt and Swiss-style yogurt. Set-style yogurt is poured into containers to set, while Swiss-style yogurt is stirred before packaging. Either type can have fruit added to make it sweeter.

Lassi is a popular drink from India made from stirred yogurt that can be salty or sweetened with sugar (or sometimes honey) and combined with fruit. The texture can vary, with city-made lassi being smooth and rural lassi having chunks or fruit pieces.

Commercial yogurts often have large amounts of sugar or other sweeteners for low-energy versions. Some have added modified starch, pectin (a natural fruit thickening agent) or gelatin to make them thicker and creamier. These may be called Swiss-style, but they are not the same as real Swiss yogurt. Some yogurts, called "cream line", use whole milk that has not been mixed so the cream stays on top. Sweetened and flavored yogurts are common around the world, sold in single-serving plastic cups. Popular flavors include vanilla, honey, and toffee, as well as various fruits. Recently, yogurt flavors inspired by desserts like chocolate or cheesecake have become popular. There is concern about the health effects of sweetened yogurt because of its high sugar content, though sugar use in yogurt making has gone down since 2016 due to WHO and government efforts to fight obesity.

Straining

Main article: Strained yogurt

Strained yogurt has been poured through a filter, usually made of cloth, to remove the liquid called whey, making it thicker. This is often done at home, especially when using low-fat milk. Strained yogurt in Middle Eastern countries is called labneh. It is thicker than regular yogurt but thinner than cheese, and can be used in sandwiches. It may include olive oil, cucumber, olives, and herbs. It can be made even thicker, rolled into balls, kept in olive oil, and fermented longer. It is also used with onions, meat, and nuts to fill pies or kibbeh balls.

Some strained yogurts are first boiled to reduce the liquid. A sweet Indian dessert called mishti dahi is a thicker, sweeter version of traditional dahi. In western India, strained yogurt mixed with sugar and spices like saffron and cardamom makes the dessert "shrikhand". Strained yogurt is also a main part of tzatziki, a sauce for gyros and souvlaki sandwiches, made with strained yogurt, grated cucumber, olive oil, salt, and sometimes garlic. Srikhand is an Indian dessert made from strained yogurt, saffron, cardamom, nutmeg and sugar, and sometimes fruits like mango or pineapple.

In North America, strained yogurt is often called "Greek yogurt". Sometimes powdered milk is added instead of straining to make it thick. In Britain, only yogurt made in Greece can be called "Greek".

Beverages

Ayran, doogh ("dawghe" in Neo-Aramaic) or dhallë is a salty drink made from yogurt mixed with water and sometimes salt.

Borhani (or burhani) is a spicy yogurt drink from Bangladesh. It is often served with kacchi biryani at weddings and special meals. It is made from yogurt mixed with mint leaves (mentha), mustard seeds and black rock salt (Kala Namak). Spices like roasted cumin, white pepper, green chili pepper paste and sugar are also added.

Lassi is a yogurt drink that can be slightly salty or sweet, and may have added flavors like rosewater, mango or fruit juice. Salty lassi often includes roasted cumin and red chilies, and may be made with buttermilk.

An unsweetened yogurt drink called jogurt is enjoyed with burek and other baked goods in the Balkans. In Europe (including the UK) and the US, sweetened yogurt drinks with fruit and added sugar are common, called "drinkable yogurt". There are also "yogurt smoothies" that have more fruit and are like smoothies.^{[citation needed]}

Production

Yogurt is made by heating milk to a warm temperature (between 30–45 °C or 86–113 °F) so it doesn’t kill the helpful tiny living things that turn milk into yogurt. Special bacteria, usually Streptococcus thermophilus and Lactobacillus bulgaricus, are added to the warm milk. The milk is kept warm for several hours to let the yogurt form.

Sometimes, milk with more solids is used to make the yogurt firmer. This can be done by adding dried milk. The way yogurt is made helps keep it safe by using heat and natural acids. Even though some harmful germs can survive acids, the heat used when preparing the milk stops them. After the yogurt is made, it can be strained to make it thicker by removing some of the liquid.

Microstructure

Yogurt is a thick, smooth food that changes shape when you stir it or move it around. It forms when milk is changed by tiny living things called bacteria. This process makes the proteins in the milk clump together, creating the soft, creamy texture of yogurt.

The way yogurt looks and feels depends on how much fat and protein is in the milk used to make it, as well as how it is processed. Yogurt made from different kinds of milk, like goat or sheep milk, can feel thinner or thicker than yogurt made from cow milk. Some yogurts are stirred during making, which gives them a coarser texture, while others are left undisturbed, keeping a smoother consistency.

Commerce

There are two main types of yogurt recognized for trading between countries. One type is pasteurized yogurt, which is heated to remove bacteria. The other is probiotic yogurt, also called live or active yogurt. This type is pasteurized first, and then specific bacteria called Lactobacillus are added before it is packaged. There is also a drinkable version of probiotic yogurt.

In the United States, rules say that milk must be pasteurized before it is turned into yogurt. Sometimes, it gets heated again after to make it last longer, but most commercial yogurts do not have this extra step and still contain live cultures. Yogurt with live cultures can be especially helpful for people who have trouble digesting lactose.

Lactose intolerance

Lactose intolerance is when people have trouble digesting lactose, a sugar found in milk and other dairy products. In 2010, the European Food Safety Authority said that eating live yogurt cultures (lactobacilli) can help people with lactose intolerance. These live cultures can break down the lactose in other dairy foods. To make this claim on labels, yogurt must have at least 10⁸ live microorganisms per gram. A review in 2021 also found that eating yogurt can help improve how well people digest lactose.

Plant-based products

In the 2000s, people started making yogurt-like foods from plant-based liquids such as soy milk, rice milk, almond milk, and coconut milk. These are made by using special bacteria to ferment the liquids. They can be good for people who can't digest lactose well or who choose not to eat animal products, like vegans.

Plant-based liquids are different from regular milk, so these products might taste or feel a little different. In some places, like Europe, companies aren't allowed to call these products "yogurt" because that word is only for foods made from animal milk.

Ant yogurt

Red wood ants are used in Bulgaria and Turkey to make a special kind of yogurt. A few ants are added to warm milk and left to ferment. Scientists think the ants help make the milk sour and allow helpful tiny living things from the ants to grow. These tiny living things also help break down the milk proteins to create yogurt.