Yogurt

Yogurt is the Turkish word for milk that has been fermented into a tart, semisolid mass; it comes from a root meaning “thick.” Essentially the same product has been made for millennia from eastern Europe and North Africa across central Asia to India, where it goes by a variety of names and is used for a variety of purposes: it’s eaten on its own, diluted into drinks, mixed into dressings, and used as an ingredient in soups, baked goods, and sweets.

Yogurt remained an exotic curiosity in Europe until early in the 20th century, when the Nobel Prize–winning immunologist Ilya Metchnikov connected the longevity of certain groups in Bulgaria, Russia, France, and the United States with their consumption of fermented milks, which he theorized would acidify the digestive tract and prevent pathogenic bacteria from growing (see box). Factory-scale production and milder yogurts flavored with fruit were developed in the late 1920s, and broader popularity came in the 1960s with Swiss improvements in the inclusion of flavors and fruits and the French development of a stable, creamy stirred version.