Our Sense of TASTE

By Jill Misterka

A glass of wine, a good meal with friends, a box of chocolates—many joys in life involve our sense of taste. We’ll be talking about that sense with a focus on wine tasting. Gustation, the formal name for the sense of taste, comes from our taste buds so we will start with a discussion of their physical structure and how they work.

What are taste buds?

Those little bumps we see on our tongue are called papillae. Many of them have taste buds sitting on top. Each taste bud is cup shaped, with 50 to 150 receptor cells lining its interior. Each receptor cell has a tiny hair sticking out (the gustatory hair) that reacts to wine or food that enters the taste bud. If we lose some receptor cells because of hot coffee or jalapenos, no need to fear—every three to fourteen days they are replaced by new cells.

Winery tour guides may recommend swirling a sip of wine slowly around the mouth to get its maximum flavor. Why? Because taste buds are present not only all over the tongue but also on the soft palate at the back roof of the mouth. Furthermore, it’s possible to savor a sip even as the wine is swallowed since there are also a few taste buds in the upper portion of the esophagus and in the epiglottis, the flap that blocks food from the windpipe.

What they can taste

Taste buds can detect five elements of taste perception: sweet, sour, salty, bitter, and umami (or savory). Every single taste experience, including wine, is made up of a combination of these five basic elements, though there's some debate about the existence of a sixth taste perception for fat, too.

Sweet, sour, salty and bitter are self-explanatory, but what is umami? That is the taste of glutamate, found in bacon, monosodium glutamate (MSG) and other foods. It was named by its discoverer, a Japanese scientist from the early 1900s named Kikunae Ikeda. However, American and European scientists were unaware of or ignored that discovery for many years, and recognized only the other four taste elements until recently.

Furthermore, a mistranslation by an American psychologist of a German paper written in 1901 about Japanese research caused another mistake: the Tongue Map. For many years the scientific understanding was that each section of the tongue could taste only one of the four recognized elements. That was wrong. Although the level of sensitivity varies, all areas of the tongue can taste all of the taste elements. This applies to other regions of the mouth where there are taste buds as well.

How many taste buds do we have?

A healthy human tongue can have 2,000 to 10,000 taste buds. Why does the number matter? In general, a person's ability to taste increases in proportion to the number of taste buds he or she has.

Having a stronger or weaker ability to taste due to the amount of taste buds greatly affects what foods people like. A food with a strong flavor is more likely to be favored by someone with fewer taste buds, while a person with more may find that same food’s taste too over­whelming to be pleasurable. In other words, those of us who find Starbucks coffee undrinkably bitter probably have more taste buds than average.

It seems likely that wines can have the same effect. A high-acid dry red will be less appealing to a sensitive taster, while it may taste wonderful to someone with less abundant taste buds. On the other hand, the sensi­tive taster may prefer a lower-acid or sweeter wine that is disgustingly bland to the fewer-taste-buds drinker.

What decides how many taste buds we have? The number is affected by:

Genetics  Inheritance determined how many taste buds we were born with.

Gender  Women tend to have more taste buds than men.

Age  The receptor cells in the taste buds are not replaced as fast as we get older, thus reducing the number of “working” taste buds.

Some animals have many more taste buds than humans do. For example, rabbits are said to have 17,000 taste buds and cows 25,000. And for some animals, the sense of taste is not just in the mouth. Catfish have receptor cells on the outside of their body while flies and butterflies have them on their feet, so each can tell immediately upon touch whether an object is good to eat.

By the way, capsaicin—the ingredient that makes hot peppers “hot”—stimulates pain receptors, not taste buds, though it can damage taste buds by giving them a chemical burn. (No word yet on whether those of us who can’t handle jalepenos have more pain receptors.)

Other factors that affect our sense of taste

Despite the important role that taste buds play in recognizing flavors, they do not work alone in providing the experience of taste. Some other factors that contribute are:

Culture and familiarity  We tend to like those tastes we grew up with and are used to.

Sense of smell  Food in the mouth produces an odor that reaches the nose through the nasopharynx, the opening that links the mouth and the nose. The nose is more sensitive to odors than the mouth is to flavors, which can enhance the taste experience in the case of good wine, or ruin it in the case of a wine with hydrogen sulfide problems.

The amount of both saliva and the naturally occurring salt in saliva  Those with less saliva or more salt in their saliva experience a relatively saltier taste no matter what they eat or drink.

Baldness  Yes, you read that right. The actual chemoreception process going on in a taste bud is dependent on each of its receptor cells having a healthy gustatory hair. Losing either those hairs or the olfactory cilliae inside the nose will result in a reduction or loss of the ability to taste (no confirmation yet whether this is related to male pattern baldness).

Nerve health  Four different types of nerves connect each taste bud to different parts of the brain, so it’s rare that disease or injury to nerves completely knocks out the sense of taste.

Food texture  Wine is said to have body when it gives a feeling of thickness or heaviness in the mouth, which is a more desirable mouthfeel than being watery.

Food temperature  Wine will taste different depending on whether it’s served chilled or at room temperature.

Aftertastes in the mouth  This is the reason that wineries often serve water or bowls of small crackers with wine, so customers can “cleanse their palate” between glasses.

The most important factor of all

The brain  The taste buds provide information about the taste of food being eaten, but the brain is the organ that interprets the taste and decides if it’s desirable or not.

And since the brain is our center of learning, it is possible to retrain our sense of taste despite all these other factors. In fact, professional wine tasters go through training classes to help them distinguish the various individual odor and taste notes that may be present in wine, using kits containing small containers of flavored extracts. Once trained, their noses and tongues can determine if there are vanilla or asparagus notes in the wine, for example.

What can we conclude?

Even when a roomful of people are partaking of the same wine, each person is experiencing it little differently. Taste is an amazing sense, one that makes life more enjoyable and makes us unique compared to other people. The next glass of wine you drink will taste better now that you appreciate what’s going on in there!

Sources: www.livescience.com; en.wikipedia.org; faculty.washington.edu; www-psych.stanford.edu; Encyclopedia of Nursing and Allied Health.

Photo credit: © Paul Moore/photoxpress.com

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