From your first sip of morning coffee to the minty zing of toothpaste before bed, your tongue is bombarded daily with a flood of flavors. How we disentangle and identify all those tastes is still pretty mysterious. That’s starting to change, though, as researchers unlock the secrets of flavor.
Several taste experts spoke at a symposium on “The Science of Eating: Perception and Preference in Human Taste” on February 19 at the annual meeting of the American Association for the Advancement of Science (AAAS), held this year in Washington, D.C.
A couple of decades ago, the established number of basic tastes went from four to five, with the addition of umami — the savory taste of Parmesan cheese and sundried tomatoes — to the traditional grouping of salty, sweet, sour, and bitter. But there’s much more to flavor than those five tastes.
Most of what we think of as flavor is really aroma. To the taste buds on your tongue, a lemon and a lime are both just sour. It’s your nose that tells you which citrus you’re swallowing.
Food scientists envision flavor as a medley of factors, including taste, odor, texture, and even irritation — a familiar component of spicy chilies. “Tastes, aromas, and mouthfeel factors are rich sources of stimulation throughout our lives,” said Jane Leland, a food scientist at Kraft Foods in Glenview, Ill., in an interview before the symposium.
Many other factors play a role in shaping our fondness for flavors. Both before and after birth, babies get a hint of the foods their mothers consume via taste and odor compounds that get into amniotic fluid and breast milk. Studies show that children have a preference for flavors they were first exposed to this way, Beauchamp said.
Cultural factors, too, influence which foods you love or hate. If you grew up eating spicy curries or seaweed salad, those preferences can stick with you longer than other cultural carryovers.
We may feel strongly about certain foods, but precisely how we taste them is still an open question. Our taste buds contain a variety of specialized chemical structures, known as receptors, that latch onto molecules characteristic of particular tastes, signaling their presence to our brains. But scientists have not yet identified all the receptors that do this job. Some researchers have even begun to suspect that there are more than just five basic tastes. According to some, we may also have receptors for compounds such as fat, calcium, and carbon dioxide.
A recent surprise for taste scientists has been the discovery of receptors for the basic tastes not only on the tongue, but also in the airways and the intestines. Scientists believe the receptors throughout the digestive tract may help coordinate the body’s hormone response to food nutrients. One such response might be how full we feel after eating certain foods. If that’s so, it might be possible one day to combat overeating by finding ways to trick the gut receptors into thinking we’ve had enough.
However, there are many things we still don’t know about taste, but research is in progress and that day is hopefully not very far when the science of taste will be as clear to us as the laws of motion. 
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