By Harold McGee
Our ingenious prehistoric ancestors discovered no fewer than three different ways to turn grains into alcohol! The key to each was enzymes that convert the grain starch into fermentable sugars. Because every enzyme molecule can do its starch-splitting operation perhaps a million times, a small quantity of the enzyme source can digest a large quantity of starch into fermentable sugars. Inca women found the enzymes in their own saliva: they made chicha by chewing on ground corn, then mixing that corn with cooked corn. In the Far East, brewers found the enzymes in a mold, Aspergillus oryzae, which readily grew on cooked rice. This preparation, called the chhü in China, koji in Japan, was then mixed with a fresh batch of cooked rice. In the Near East, the grain itself supplied the enzyme. Brewers soaked the grain in water and allowed it to germinate for several days, then heated the ground seedling with ungerminated grain. This technique, called malting, is the one most widely used today to make beer.