Taste: Surprising Stories and Science About Why Food Tastes Good (12 page)

The taste cells in the mouth and throat are connected to three main nerves in the head called
cranial nerves
, which carry taste messages to the brain. Taste cells on the front of the tongue connect to a cranial nerve called the chorda tympani. There’s a similar body part in the ear, the tympanum, both of which share a Latin root with the tympani drum. The chorda tympani, carrying taste information to the brain, passes right through the middle ear. The glossopharyngeal nerve connects the back of the tongue.

The taste receptor cells that function as the “rubber tires” of your mouth relay information to nerves that tell the brain about what you are tasting. Even though they’re around for less than two weeks due to programmed cell death “tread replacement,” the new taste cells that replace them reestablish a connection to the brain. The fact that this connection is cut and reconnected—continually—over a course of ten days proves just how important the taste system is.

There are other sensations that we perceive as tastes that aren’t really tastes;
nor are they smells. In fact they are related to the sense of touch—the same sense that detects pain. These sensations connect to the trigeminal nerve, which also transmits touch, pain, and the indication of temperature (what you feel when you drink something hot). Other examples of trigeminal sensations in the mouth are the cooling of mint and the spicy-hot of chile peppers. When you eat a salsa that’s spicy-hot, you might say it tastes hot, but that would be incorrect (now I’m thinking like a scientist). You actually feel spicy-hot chiles. The trigeminal nerve is also the main facial nerve involved in classic migraine headaches. Not surprisingly, due to their shared relay to the brain, spicy foods are a common trigger of migraines.

We don’t know where the signals go once they move along the relay system from the taste receptor cell to the nerve to the brain. Perhaps one day we’ll have a cool map of the brain that marks sweet with a star, the way a map of the United States marks Washington, D.C., as the capital. But for now, we don’t know a lot about how taste works in the brain. The boss keeps his secrets well hidden.

I’m asking you to do this experiment with your eyes closed. Read it thoroughly up to the spoiler alert before attempting to do it. That way, you’ll know what to expect.

YOU WILL NEED

A bowl of jelly beans of various flavors (I am partial to Jelly Belly brand because they have very complex, realistic flavors)

If you are opposed to eating candy, I suggest you use a basket of mixed bite-size fruit such as grapes, strawberries, raspberries, and blueberries.

DIRECTIONS

1. Close your eyes and pinch your nose shut with one hand, so that you cannot breathe through your nose.

2. Without releasing your nose, put your other hand in the bowl, mix up the contents, pick one piece, and put it in your mouth without looking at it. (The idea is to remain unaware of what you are putting in your mouth.)

3. Begin to chew, slowly, without releasing your nose. Keep chewing.

4. Keep chewing, and without releasing your nose, think about what you taste. Sweet? Sour? Can you tell what flavor it is?

5. Release your nose.

SPOILER ALERT!!!

OBSERVE

1. When your nose is pinched, it’s likely you’ll taste only sweet and sour. That’s because those are the only two Basic Tastes that exist in most jelly beans and fruit. With your nose shut, your tongue—or gustatory system—is doing the best it can by identifying which Basic Tastes are present.

2. What happens when you release your nose is that the volatile aromas from the jelly bean escape back up through your nasal passages, into your olfactory system, where you experience smell. This system has a lot more than just five smells to work with. There are reportedly thousands of aromas that humans can detect.

YOU WILL NEED

1 cup distilled white vinegar (any kind of vinegar will do, but distilled has the cleanest one-dimensional sour taste)

Shallow bowl or ramekin

1 cotton swab for each person who will taste

Saltine crackers and water for each taster

A handheld mirror for everyone who will be tasting

DIRECTIONS

1. Pour the vinegar into a shallow bowl or ramekin.

2. Dip the cotton swab into the vinegar.

3. Swab your tongue/mouth in distinct places, in order, being careful not to swallow or close your mouth until you’ve swabbed and tasted the spot you’re exploring. You may want to break this up into four exercises.

a. Cleanse your palate with a saltine and water. Swab the middle of your tongue.

b. Cleanse your palate with a saltine and water. Swab the sides of your tongue.

c. Cleanse your palate with a saltine and water. Swab the back of your tongue.

d. Cleanse your palate with a saltine and water. Swab the insides of your cheeks.

OBSERVE

1. As you touch the swab around your mouth, notice what you experience.

2. What you are experiencing is the sour taste. Most people experience the sour taste on all tissues in the mouth.

3. You’ve just disproved the taste map diagram!

It’s easy to prove that you can detect all tastes on all parts of the tongue. What’s harder to prove is that this theory is completely wrong, which it is not. There
are
slight differences in the intensity at which we taste things in each area of the tongue. This truth is where the taste map originated.

Volatiles are where the action is.

Harry Klee, University of Florida

I
f you stop people on the street and ask them which one of the five senses they’d be willing to give up, the most likely response will be smell. In fact,
The Escapist
magazine conducted an online poll of its readers and the results from 772 respondents were unequivocal: smell would be the first to go. But people don’t understand that what we taste is largely what we smell. While the taste committee’s role is critically important, it is smell that gives us pleasure from foods. After all, your flavor world without smell would contain only five things.

Like all high-performing organizations, our smell and taste “teams” need to work closely together to accomplish their shared objective: recognizing what’s in our mouth and making a decision about it. Consider just how closely taste
and smell work together: retronasal olfaction is all about smelling through your mouth. You simply cannot dissociate the two. Which sense is doing the heavy lifting? Which deserves the credit? Which has the power?

Scientists estimate that between 75 and 95 percent of what we “taste” is actually smell. So that smell committee member is responsible for a lot more of the final product (the brain’s perception of taste) than the taste committee. Smell is so important to the business of taste that losing your sense of smell can practically make taste disappear. If you’ve ever had a cold, you know this. Or, if you did the jelly bean exercise in the previous chapter, you experienced it.