Homemade Yogurt

Yoghurt is milk fermented by bacteria, and making it at home requires two things: milk, and a spoonful of existing yoghurt to introduce the culture. The process is worth understanding because it explains every step. Milk is heated, then cooled to around body temperature, and a live culture is stirred in. The bacteria, chiefly Lactobacillus bulgaricus and Streptococcus thermophilus, consume the lactose and produce lactic acid. That acid is what gives yoghurt its tang and what causes the milk proteins to coagulate into a set. Everything about the method exists to keep those bacteria in the temperature range where they work. Which is why the two common failures are temperature failures. Milk still too hot kills the culture outright; milk too cool, or a room too cold, and the bacteria work too slowly to set. Longer fermentation gives a tangier, firmer result. Straining it afterwards produces a thicker yoghurt, and taken far enough, something close to labneh or Greek-style yoghurt. **Filed as Worldwide**, fermented milk is genuinely global, with strong traditions across Africa, but the recipe makes no specific national claim.