Taste: Surprising Stories and Science About Why Food Tastes Good (11 page)

How does the information from the aromas and tastes that are released from food make it to your brain? Not surprisingly, the process begins on your tongue, the upper surface of which is covered with taste buds. How many buds you have determines your taster type (HyperTaster, Taster, or Tolerant Taster). Each taste bud contains millions of cells, most of whose surfaces are covered with taste receptors—proteins that recognize molecules in food and communicate that information to the cell itself, which in turn sends signals through nerves to the brain. While most receptor-bearing cells are in the taste buds, they are also present on the roof of your mouth, on the sides of your mouth, and in your throat.

There are horrific accounts of people who have had their tongues cut out who sometimes report still being able to taste, although swallowing is a problem. Swallowing is critically important to tasting because it triggers mouth-smelling. I’m skeptical of people who say they can savor a food or wine fully by swishing it around in their mouth and then spitting it out. In my professional opinion, you miss nuances of flavor when you don’t swallow. Mouth-smelling continues as you swallow food, so spitting it out cuts off the flavor process perception from its natural progression.

For example, we experience the bitter Basic Taste most strongly at the back of the tongue. If swish-and-spit tasters doesn’t allow the food to fully saturate those bitter-sensitive buds, their perception will be misinformed. Nonswallowers might argue that in certain circumstances, it may not be possible to swallow everything you taste. In some wine competitions, judges have to taste 100 or more wines in a single day, and one can only imagine the state they would be in if they’d swallowed even 100 small sips of each wine. My counterargument—independent
of concerns about alcohol consumption—would be that these competitions make their judges taste too many wines in a single day. No one, no matter how good a taster she is, can discriminate between that many wines. A phenomenon called
taste adaptation
sets in after your tongue has been exposed to too many tastes in a short interval.

With each additional sample of a taste, you become more and more adapted to that taste: this means that you require more and more of it to get a similar level of intensity. Michael O’Mahony of the food science department at the University of California Davis writes,

A constant odor or taste stimulus will be perceived as decreasing in intensity while sensitivity to that stimulus is also decreased. For sensory evaluation, this poses problems. It means that a taste or odor has a tendency to vanish while it is being observed and that sensitivity to subsequent stimuli will be altered. Such sensitivity drift in the human instrument must be anticipated in the design of measurement procedures for the sensory evaluation of food.

And wine, I argue. The phenomenon of taste and smell adaptation gives overly intense wines an advantage if they are tasted late in the day, but puts them at a disadvantage if they are tasted early. Vice versa for subtle wines. If only the “human instrument”—our mouth, tongue, nose, eyes, ears, and brain—were less prone to the failures and foibles of the human condition.

Adaptation is also the reason you can’t taste your own saliva. Your saliva contains sodium and potassium chloride, which make it slightly salty. Yet I’m sure you don’t think of your mouth as having a salty taste. That’s because you’re adapted to it. Your taste cells are in constant contact with it twenty-four hours a day. In fact, the makeup of your saliva is changing all the time, but in such small increments that you don’t notice it. It takes a rapid increase in the concentration of salt in your mouth to wake up your adapted taste buds so that you recognize it as salty. This happens when you eat.

Your own saliva is possibly the only thing in the world that you will perceive as having zero flavor. Even water differs in composition from your saliva, so you experience water as having some sort of taste. You’ve probably even said something along the lines of “It tastes like water.”

Chef Grant Achatz, of Alinea restaurant in Chicago, serves a twenty-three-course menu of small bites. This addresses the impact of adaptation, which he
refers to as the law of diminishing returns. He understands that people don’t need twenty-four ounces of steak to satisfy their craving. When talking about his tasting menu he says,

That’s why the steak is only two ounces. By your fifth bite, you’re really done with that steak. You know what it’s going to taste like. The actual flavor starts to deaden on the palate. If we were to make you take ten more bites, by the time you got to bite fifteen, the steak’s just not that compelling anymore. So if we have a series of twenty-three small courses, where it’s a burst of flavor on the palate, then you move on to something completely different . . . and then completely different. That helps us set up a more exciting meal.

When something tastes wrong, your body usually won’t let you swallow. That’s a good thing: it means your taste system is effectively serving its role as gatekeeper of the body. When and if you swallow, your sinuses get a burst of flavorful vapors from the wad of food your tongue forces to the back of your throat. Technically the wad is called a
bolus
, although that term somehow manages to be even more unappetizing than wad. Again, this will happen only if you’re breathing, something that I recommend you do constantly while you chew, and carefully when you swallow. You will continue to taste the food as long as the volatile aromas are being drawn back up into your nose through the normal course of chewing, breathing, and swallowing.

And that’s it. The conscious tasting part of eating is over. To summarize,
you derive the initial pleasure of tasting food only while it’s in your mouth and throat. This is pretty obvious when you stop to think about it. But that’s the problem: we don’t often stop to think about savoring food. We’re too busy reaching for the next mouthful. If you really want to taste something, it’s a good idea to keep it in your mouth as long as possible. Put your fork down. Take a few breaths. Chew some more. Swish it around. Then swallow. From that point forward, your food follows a very well-documented, studied path through your digestive tract.

I called the previous process the
conscious
part of tasting because scientists have recently discovered that we have taste cells much farther along in the digestive tract. There are cells in your stomach, small intestine, and pancreas that look and act exactly like those in your mouth. This was a surprise at first, says Monell scientist Bob Margolskee, but it makes sense: the gut needs to be able to identify food in order to know what to do with it.

“Our stomach and our intestines want to know what we’ve consumed. Then they can respond in the appropriate way by turning up the digestive juices,” he says. This phenomenon is known as
gastrointestinal chemosensation.
Even though we are not really conscious of tasting food much farther than our throat, our gut “tastes” nutrients and responds accordingly.

All of the sensory processes I’ve described thus far have one thing in common: their connection to the brain. When it comes to taste, this connection is an everyday matter of life or death. Making the wrong everyday choices with other senses, such as what music to listen to or what image to look at, may harm you, but probably won’t kill you. But making the wrong choice about what to eat can be lethal. Your taste system is set up to give important information to the brain instantaneously so that the body can react accordingly. To quote Monell scientist Danielle Reed, “Tasting is deciding.”

Of course, the system has its flaws. Many poisonous mushrooms are reported to be delicious, although the person who reported this probably ended up experiencing liver or kidney failure, a common side effect of the toxins that can be fatal. Or a rogue mushroom eater might develop a conditioned aversion to them in the future (if he survived). With a conditioned aversion, an eater associates a particular food with a bad outcome, and then avoids the food consciously or unconsciously. A not-so-careful wild mushroom forager might love the taste of those death cap mushrooms as they’re going down the first time, but he may develop an aversion to—a dislike of—all mushrooms in general as a result of vomiting or otherwise getting sick from them. He’ll probably be most averse to
the straw mushroom, which looks like the death cap’s identical twin. It’s amazing what puking—or liver or kidney failure—will do to your food preferences. An old adage captures this survival mechanism: there are old mushroom foragers, and bold mushroom foragers, but there are no old, bold mushroom foragers.

I call conditioned aversions the
Tequila Effect.
Anyone who has drunk too much tequila and subsequently prayed to the porcelain god knows of what I write. For a period of time after you get sick from a certain food, you will recoil at the mere smell of it. In fact, it often takes disguising the offensive food to get you to ingest it again, such as by adding lime juice and triple sec, and salting the rim of the glass.

Another way Mother Nature can fool us is with dangerous compounds like botulinum toxin, which are flavorless. While lower doses administered topically under the brand name Botox can give you an unnaturally smooth forehead, higher doses ingested orally can result in muscle weakness, paralysis, and even death. These exceptions to the rules of taste are rare, however. Most wholesome, safe food tastes good. Most spoiled or poisonous food tastes bad. Your sense of taste gives you information as it gives you pleasure.

I have seen lots of depictions of the taste system, technical illustrations of the tongue and taste buds that are tough to decipher. But you probably don’t care about discerning the difference between the fungiform papillae (the taste buds at the front of your tongue) and the vallate papillae (those at the back). To describe the physiology of taste without getting too bogged down in the science, Monell’s Danielle Reed gave me one of the best analogies for how taste works: it’s like a committee meeting in your mouth.

Imagine your mouth as a meeting room full of business colleagues who serve on the taste committee. Each has been elected to represent others like themselves in the organization: a true democracy. These colleagues work together to tackle projects (food). The committee members get together frequently to discuss new projects (incoming food) and report to the boss (your brain). The five people on the committee represent each group of the taste team: Sweet, Sour, Bitter, Salt, and Umami. One or two of the members usually dominate the meetings. Sometimes they all get a word in. It depends on the project (the food). The hard work of the committee doesn’t really come together until
a member of the Retronasal Olfaction Team sweeps through the meeting room, like the flow of aromas from your mouth to your olfactory receptors. This is when the work gels.

Unless we pay really close attention to what we’re eating, or unless one of the tastes or flavors is out of balance, we usually don’t think about each taste and each aroma separately. We react to them all as if we’ve been sent a summary report from our taste and smell systems.
Pepperoni pizza
is our first conscious reaction to taking a bite of a favorite food, not
sweet, salt, sour, umami tastes combined with tomato, Parmesan, cured meat, and green herbaceous aromas
. . . ah,
pepperoni pizza.
We gloss over the details, but our brain fuses the information into one coherent packet of information.

It’s really easy to give someone a piece of pepperoni pizza and ask him what he thinks about it because we know a lot about reactions to things like pizza and other compound foods. We don’t know a lot about what happens at the level of the taste bud. Each taste bud contains many taste receptor cells, and some of these receptors detect bitter, some detect sweet, and some detect umami. Taste cells are specialized to detect only that one taste. Sweet, bitter, and umami tastes are detected when they latch onto a taste receptor in a hand-in-glove fashion. Scientists have yet to identify the ones that detect salt. Sour and salt have to pass through ion channels to be detected. It’s a harder system to study, which is why we have yet to identify the salt receptor. The fact that both are detected similarly is one of the reasons people confuse salt and sour, as they do with Keane’s risotto.