Yogurt

How it’s made

Yogurt is produced by inoculating warm milk with two thermophilic bacteria — Lactobacillus bulgaricus and Streptococcus thermophilus — and holding it at around 43 °C. The bacteria convert lactose to lactic acid, which lowers the pH, denatures milk proteins, and thickens the milk into a custardy gel. Modern dairies finish in 4–8 hours; traditional methods take overnight in a covered crock.

Plain vs. strained

• Plain (set) yogurt — fermented in its container, with a soft custardy body.
• Stirred yogurt — fermented in vats then mixed; smoother.
• Strained yogurt (Greek-style, labneh) — drained through cheesecloth to remove whey; thicker, tangier, with concentrated protein.
• Skyr — Icelandic strained yogurt-like dairy; technically a fresh cheese, but eaten as yogurt.

Around the world

• India — dahi, used in raita, lassi, and as a marinade.
• Turkey — ayran, a drinkable salted yogurt.
• Iran — mast, often served alongside rice and stews.
• Lebanon — labneh, drained until almost cream-cheese thick.
• Bulgaria — claims yogurt’s name; the standardized strain is named after the country.

Health note

Plain unsweetened yogurt with live cultures is among the most studied probiotic foods. Many flavored commercial yogurts have added sugar approaching that of soft drinks per cup.