Prof. Dr. Ayşe Baysal*
Yogurt is a food product obtained by the fermentation of milk. Fermentation is one of the oldest methods of preserving food. Brought about by microorganisms, the fermentation process may occur naturally and is used in the production of many different food products. Microorganisms including yeasts, molds and bacteria may be both beneficial and harmful to mankind. Chief among the “friendly” bacteria are the lactic acid and bifidobacteria, some of which belong to the Streptococcus group. These bacteria convert the sugars in milk to acid, souring the milk. The resulting acid environment both causes the milk to curdle and inhibits the growth of the bacteria. Known since very ancient times, the fermentation process in milk has been developed in recent years and used to produce yogurt of various kinds according to varying tastes. Today, yogurt, classified as a “functional food,” is high on the list of healthy foodstuffs. In this article we will examine the place of yogurt in Turkish food culture, its state in the world, and its importance from the standpoint of nutrition and health.
A Brief History of Yogurt
Certain ancient sources indicate that the fermentation of milk was already known in 2,600 B.C. The Old Testament mentions Abraham making offerings of sweet and sour milk to the angels. Although the Romans were not great consumers of milk, two recipes for sour milk occur in the autobiography of Heliogabalus, one flavored with fruits and the other with spices.
Most historians believe that fermented dairy products were first developed by nomadic peoples in Central Asia. As soon as these peoples learned to milk animals in the early Neolithic age, they discovered the method of making yogurt. In Central Asia, where summertime temperatures reach 40 C (105 F), they noticed that milk soured/clabbered after a short time. Clabber that came out smooth was called yogurt, and the uneven/lumpy variety was strained of its whey and made into cheese. The word “yogurt” comes from the Turkish verb “yoğurmak,” to knead or mould. Realizing the value of milk which had soured on its own, they developed the technique for making yogurt.
The famous Italian traveler Marco Polo wrote that the people of Central Asia boiled the milk after milking their animals, then allowed it to ferment with some of the yogurt remaining in the containers. The Oğuz Turks called this old yogurt, used as a starter, kor, which derives from the word koruk, meaning sour. In Anatolia, this starter is known as damızlık, literally, the “stud.” Yogurt was made and stored in animal skins, or in wooden or earthen vessels. Yogurt was also placed in an animal skin, known as a tuluk, and churned with a wooden implement made especially for the purpose to make butter. In the Kteadgu Bilig, this tool is known as a yayıg. Yogurt was also thinned with water to make ayran. The process of thinning yogurt for ayran was called yoğurt sütgerdi, or “the yogurt has become like milk.”
In Central Asia, other fermented milk products are made as well: kefir and kumiss (Turkishkımız). Kumiss is made from mare’s milk, and is more or less alcoholic according to the degree of fermentation. Kefir also contains a small amount of alcohol. The Turks introduced kumiss to the Chinese, who used this drink as a medicine. English missionaries referred to this drink as “cow’s milk whisky.” Today, kumiss remains an important drink among the Kazakh people.
Some historians view the Balkans as the “homeland” of yogurt. According to their view, people living in Thrace in the 4th century B.C. consumed a fermented milk product calledprokis, which later came to be called yogurt.
Just as yogurt eaten fresh and made into ayran, it is also dried for consumption during seasons when milk is scarce. Called kurut (< kurutmak, to dry), this product is commonly consumed throughout Central Asia.
The Spread of Yogurt to the Rest of the World
Turks migrating west and south from Central Asia introduced the milk fermentation process to Anatolia, the Caucasus, Russia, and the countries of East and Central Europe, as well as China and India. In these countries, the favorable climatic and environmental conditions for animal husbandry allowed increased production of yogurt’s raw material, milk.
In Turkey, yogurt holds an important place in the people’s nutrition. In a closed agricultural economy, people meet their nutritional needs with their own products. Farm families with little land would keep a cow or a few sheep, and turn their milk immediately into yogurt using starter leftover from the previous batch. In this way yogurt was eaten fresh daily; the leftovers would be allowed to age for a few days and then churned to make butter. The remaining whey was boiled with salt, which would cause it to precipitate, this produced was known as keş. Keş was both stored in vessels as well as dried for winter consumption. Yogurt was also mixed with cracked wheat or flour to produce tarhana. In rural areas of Turkey, these foods are still made. As sheep and goats are milked in spring and summer, milk is plentiful then; in winter it becomes scarcer. For this reason the various milk/yogurt products are made in the summer. During the summer yogurt and bread, as well as yogurt or ayran soup are commonly eaten; in the winter these are replaced by keş and bread, and tarhana soup. Yogurt may be used to top vegetable and grain-based dishes, as well as with pekmez(grape or mulberry molasses) or honey as a dessert.
Upon the arrival of the Middle Ages, yogurt began to take its place as an important staple in Eastern Europe, especially in the Black Sea area. In Western Thrace, goats milk was kept in a hot place to sour, then used to sour lukewarm milk. In the modern age, with the advancement of microbiology, the various microorganisms which cause the souring of milk began to be identified. Those which produce lactic acid as they ferment milk came to be known as “lactic acid bacteria.”