2. Yogurt is a sweet and sour milk drink. It is a dairy product which takes milk as raw material, adds beneficial bacteria (starter) to pasteurized milk, ferments, and then cools and fills.
Historical evidence shows that yogurt has been used as food for at least 4500 years. The earliest yogurt may be milk packed in sheepskin bags by nomads, which was naturally fermented by bacteria attached to the bags and turned into cheese.
4. More than 2000 years ago BC, the ancient Thracians living in northeast Greece and Bulgaria also mastered the technology of making yogurt. They started with goat's milk. Later, yogurt technology was spread to other parts of Europe by the ancient Greeks.