plain yogurt

Plain yogurt (Bos taurus, fermented milk) turns up in three recipes at three scales. The jameed-free mansaf takes 2000 g of full-fat plain yogurt, whisked off the heat with ayran, an egg and cornstarch, then stirred without stopping as hot lamb broth goes in, until the sauce reaches a gentle boil. Abo shalhoob is served with 200 g of cold plain yogurt, about 50 g a plate, or the yogurt beaten with garlic and lemon juice. The two-kiwi smoothie blends in 100 g, lactose-free if lactose troubles you.

The Journal's note on lactase persistence treats the tang and the set as one event. Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus feed each other and turn lactose into lactic acid. Milk starts near pH 6.8; as it falls toward 4.6 the casein micelles lose the charge that keeps them apart and lock into a network, which is set yogurt. The same note says people who cannot digest lactose usually tolerate yogurt better than milk, because the bacteria bring their own enzyme. The European Food Safety Authority authorises that claim only for yogurt carrying at least a hundred million live starter organisms per gram when eaten, so heat-treated yogurt does not qualify.

The bloating note puts a number on it. In 1984 Kolars and colleagues fed volunteers 18 g of lactose as yogurt, as milk and in water, and measured a third as much breath hydrogen after the yogurt. A 100 g spoon of plain yogurt holds about 5 g of lactose, under half the roughly 12 g that most lactose-intolerant adults tolerate in one sitting, and part of it is digested on arrival. The lactase note adds that the longevity story about Bulgarian peasants rested on birth records that could not support it.