On Food and Cooking

milk of their new home.
The handful of fresh fermented milks
familiar in the West, yogurt and soured
creams and buttermilk, represent two major
families that developed from the dairying
habits of peoples in two very different
climates.
Yogurt and its relatives are native to a
broad and climatically warm area of central
and southwest Asia and the Middle East, an
area that includes the probable home of
dairying, and where some peoples still store
milk in animal stomachs and skins. The
lactobacilli and streptococci that produce
yogurt are “thermophilic,” or heat-loving
species that may have come from the cattle
themselves. They’re distinguished by their
ability to grow rapidly and synergistically at
temperatures up to 113ºF/45ºC, and to
generate high levels of preservative lactic
acid. They can set milk into a very tart gel in
just two or three hours.