MODERN LIVING: Old Indian Trick

For centuries the Indians of Latin America have wrapped their tough, fresh-killed meat in leaves from the papaya tree before cooking it. They never knew why. but the leaves made the meat tender, kept in its juices. For decades scientists have known why: papaya leaf and the juice of the papaya fruit contain an enzyme which breaks down protein tissue in the same way as the stomach's digestive juices.

Despite this knowledge, dozens of attempts to make and sell commercial meat tenderizers made from papaya had little success, for the simple reason that users could not control the reaction. Most...