Yogurt

Yogurt is a creamy food created through the bacterial fermentation of milk. This biological process transforms liquid milk into a thickened substance with a distinct, tart flavor.

The transformation occurs when specific bacteria consume the natural sugars found in milk. As these bacteria eat the sugars, they produce lactic acid. This acid acts on the milk proteins, changing the texture and creating the characteristic acidity. While cow's milk is the most common base, yogurt can also be produced from the milk of water buffalo, goats, ewes, mares, camels, and yaks.

To create yogurt, a specific bacterial culture must be introduced to the milk. This culture typically consists of two main types of bacteria: Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus.

Once the culture is mixed in, the milk must be kept at a warm temperature for a period of 4 to 12 hours. Maintaining this warmth allows the fermentation to occur effectively. However, producers must be careful with the heat levels. If the temperature is too high, the yogurt may develop a lumpy texture or experience whey separation. Some people prefer a thicker consistency and may use a filter to strain the liquid.

Different regions have different rules and styles for yogurt. In France, a product can only be labeled as "yaourt" if it was fermented exclusively by the two standard bacteria mentioned earlier. This follows international standards set by the Codex Alimentarius. Other countries, such as China, regulate the amount of live bacteria present. In China, yogurt must contain at least 1 million colony-forming units (CFU) of Lactobacillus bacteria per milliliter. Some manufacturers also add other types of bacteria, such as bifidobacteria, during or after the culturing process to change the final product.

The exact origins of yogurt are unknown, but it was likely discovered by chance. Scientists believe Neolithic people in Central Asia and Mesopotamia may have first made it around 5000 BC. This was around the same time that humans began domesticating milk-producing animals. Early yogurt may have been created spontaneously by wild bacteria inside goat skin bags.

The word itself comes from Old Turkic roots, such as the word "yuġrut," which is related to terms meaning to knead or to thicken. Historical texts from the 11th century, like the Dīwān Lughāt al-Turk, describe its use by nomadic Turks.

Modern science helped turn yogurt from a traditional staple into a global industry. In 1905, a Bulgarian student named Stamen Grigorov identified the specific lactic acid-producing bacteria in Bulgarian yogurt. Shortly after, the rod-like bacterium was named Bacillus bulgaricus.

Following this discovery, the Nobel laureate Ilya Mechnikov hypothesized that eating yogurt helped Bulgarian peasants live longer lives. He worked to popularize the food throughout Europe. Industrialization began in 1919 when Isaac Carasso started a business in Spain called Danone. In the United States, the food became even more popular when companies like Colombo Yogurt added fruit preserves to the bottom of the container in 1966.

Nutritionally, plain yogurt made from whole milk is quite complex. It is composed of 81% water, 9% protein, 5% fat, and 4% carbohydrates.

A single serving is a rich source of vitamin B12, providing 31% of the Daily Value (DV), and riboflavin, providing 23% DV. It also contains moderate amounts of phosphorus and selenium. While many people eat yogurt for its potential health benefits, such as improved lactose tolerance or bone health, scientific reviews note that high-quality evidence is still being studied. Some research suggests that eating 50 grams of yogurt daily may reduce the risk of obesity by 13%.

Yogurt is deeply woven into the traditions of many cultures around the world. In Nepal, it is called dahi and is used in marriage ceremonies and religious festivals. In India, dahi is a significant part of the diet and is even used in Hindu rituals.

Different regions have unique ways of serving it, such as the cold yogurt soup served in Northern Iran or the creamy Tzatziki used as a sauce in Greece. Because yogurt is a living product, safety is important. Yogurt made from raw milk can carry harmful bacteria, and if mold forms on the surface, it can penetrate deep into the yogurt due to its consistency.