A MATTER OF TASTE

THE TONGUE, THE NOSE, AND THE BRAIN ALL WORK TOGETHER TO NOTICE FLAVORS.

- by Jeanne Miller

Have you ever tried the jelly bean test? It's an experiment that proves the importance of the nose in the sense we call "taste." Hold your nose closed and put a jelly bean or some other fruit-flavored candy in your mouth. Chew the candy. You'll taste sweetness and maybe a little sourness but not much else. Then open your nose. Suddenly, you'll get the full force of the fruit flavor. Chewing releases molecules, which are groups of atoms stuck together, in the candy. In the mouth, these molecules trigger basic tastes: sweet, salty, sour, and bitter. Odor molecules also float from the back of the mouth up into the nose.

THE CHEMICAL SENSES

The little bumps on your tongue are called papillae. They hide tiny taste buds. Inside the taste buds are even smaller structures called receptors. When a sweet food molecule reaches a sweet receptor, it fits into it like the last piece of a jigsaw puzzle. The same is true for a bitter food molecule—it has a different shape that matches a different receptor. When a molecule locks into a matching receptor, a chemical signal goes to the brain that says, “Sweet!” or “Bitter!”

With salty and sour tastes, the process is a little different; it’s not shape-based. Still, these taste molecules stimulate receptors on the tongue, causing a signal to travel to the brain. The signal reveals there’s something salty or sour in the mouth.

Meanwhile, in the nose, odor molecules bind to some of the many receptors there and send their own signals to the brain. These pathways to the brain are separate from the taste buds’ paths. When the brain combines the signals from the tongue and the nose, It figures out the food's identity from its flavor. It might announce, "Strawberry!" or "Broccoli!" or "Dill pickle!"