National Geographic : 2015 Dec
science of delicious 67 the Monell Center. Scientists have made great progress in recent years in identifying taste re- ceptors and the genes that code for them, but they are far from fully understanding the sensory machinery that produces our experience of food. Margolskee described it to me as “one of these Rube Goldberg devices in which the little ball rolls down and activates this thing, which acti- vates that thing, and there are about six differ- ent steps, and then a signal travels to your brain, and you either swallow what you’ve got in your mouth or spit it out.” Almost 25 years ago my wife introduced our daughter’s Brownie troop to the “tongue map,” which she’d learned about in a cookbook when she herself was a girl. Each of the basic tastes, she explained, is perceived by taste buds in a unique region on the tongue: sweet at the tip, salty and sour at the sides, bitter at the back. She gave the girls Q -tips and bowls of salt water, sugar water, and other liquids, and invited them to prove it to themselves. “I can taste everything everywhere,” one of the girls said. “No, you can’t,” my wife said. “Try again, and really pay attention.” “I can taste everything everywhere too,” said another girl. As it happens, the Brownies were right, and their leader was wrong. It’s true that in some people the receptors for particular tastes may be more concentrated in certain areas on the tongue, but all of them are found all over, and a Q -tip dipped in lemon juice will seem sour no matter where you dab it. (The receptors sit on the surface of taste cells, which are bundled together in taste buds.) The notion that each taste has its own tightly circumscribed detection zone can be traced, according to Linda Bartoshuk of the Can science create commercial tomatoes that taste the way tomatoes used to? At the University of Florida blind taste tests help researchers identify the flavors people like—and the volatile chemicals responsible. The next step: breeding tomatoes so that they produce those chemicals.