But hardly anyone talks about the tongue and the nose that make the tasting possible.

That's a shame. Without them, the wonderful world of cooking and eating would be flavorless, devoid of personality.

Luckily, food can be memorable and desirable, even rise to the level of celebration and sensuality.

Thanks, of course, to your tongue and your nose.

But that brings up a small mountain of questions. For instance:

What exactly are taste buds, how do they work with the nose and why do they work so differently in one person compared to another? Why do our tastes sometimes change? What do taste buds look like? If dogs have taste buds, how come they'll eat old shoes, cat litter and garbage? And while we all understand sweet, salty, sour and bitter, what is this new "umami" (or savory) taste that scientists discovered earlier this decade ?

We turned to two experts at the Monell Chemical Senses Center, an independent, nonprofit research institute in Philadelphia. Leslie Stein is a science communications officer who has a doctorate in physiological psychology, and Danielle Reed is an expert in the genetics of bitter taste perception.

Q: So what's new in taste research?

Stein: There's a lot of work now trying to understand taste receptors and what the mechanisms are that allow us to detect different tastes. One of the reasons why we want to understand that is to be able to tweak those mechanisms.

Take the salty taste. We still don't understand how that is detected. A complete understanding of that would be helpful if we wanted to help people decrease their salt by finding ways to enhance the taste of foods without so much sodium.

Another example is with bitter taste. The pharmaceutical companies have a vested interest in (finding bitter blockers) because most medicines are bitter. And for pediatricians, compliance is very important, so that could be very beneficial.

Why do we have a sense of taste anyway?

Stein: Our sense of taste acts as a gatekeeper when we ingest food. By analyzing food quality (sweet, bitter, salty, etc.), taste helps us decide whether to swallow something that's in our mouth.

The sense of taste sends signals to our digestive system to help the body use the nutrients in foods effectively. The taste of food in the mouth also signals nerves to cause the release of enzymes and hormones in saliva, stomach, pancreas and intestine. (This) contributes to the digestion, absorption and metabolism of nutrients.

How is it possible that we can taste things?

Reed: There are receptors on taste cells, and the chemicals in your food bind to the receptors like a key in a lock. Once the key is in the lock, then the inside of the cell responds and sends a message from the taste cell to the brain. Once the taste signal gets to the brain, the brain interprets it with either a yummy or yucky response.

What are taste buds, and how many do we have?

Stein: Humans have around 10,000 taste buds, clustered in projections called papillae. Each papillae can contain from one to 700 taste buds, depending upon its location.

Aren't all taste buds found on the tongue?

Stein: Not all. Some are found on the roof of the mouth and in the throat. Taste receptors are also found in the lining of the intestine.

The intestine? What are they doing there?

Stein: These "internal" taste receptors may play an important role in metabolic diseases such as obesity and diabetes.

Can you see taste buds on the tongue?

Reed: You can see taste papillae.

What are papillae?

Reed: Papillae is from the Latin for nipples, 'cause they look like little nipples.

So what do taste buds look like? And do they look the same, or are they different?

Reed: They look different. The ones at the front of the tongue look like little mushrooms, and the ones on the side of the tongue look like the leaves of a book.

Do different parts of the tongue detect different tastes?

Stein: Although we don't yet know if individual taste buds can detect one, multiple or all taste qualities, all areas of the tongue can recognize each taste, with some areas better at responding to certain tastes than others.

Is flavor the same as taste?

Stein: No. The distinctive flavor of most foods and drinks comes more from smell than it does from taste. Sugar has a taste (sweet), but strawberry actually is a smell. An airway between the nose and mouth lets people combine aroma with the five basic tastes to enjoy thousands of flavors.

Is there any way we can alter our taste to, say, improve our health?

Stein: Monell research has shown that people who stick to a lower-sodium diet for a period of time come to prefer lower levels of saltiness in their food. Unfortunately, we can't change our genes, (but) repeated exposure can increase relative liking for a food. But it may not be able to change a disliked food into one that is liked.

Can pregnant women "teach" their unborn child to like certain foods by eating a lot of those foods?

Reed: Oh, absolutely. That research was done here. Pregnant women were given carrot juice, and researchers found that the babies preferred carrot flavor in their cereal more than babies that weren't given carrot juice. Taste buds become active when children are still in the womb. The fetus definitely learns about the flavors through amniotic fluid and breast milk. And research does indicate that that does help a child learn to like those flavors if they were in the pregnant mother's diet.

What are all the tastes humans can sense?

Stein: Humans detect five basic taste qualities: sweet, sour, bitter, salty and savory. Savory is also known as umami.

Umami?

Stein: It's the Japanese word for "delicious essence." Recent biochemical studies have revealed a separate taste receptor that can detect this amino acid, increasing the likelihood that umami is a separate and distinct taste sensation, which perhaps evolved to ensure adequate consumption of protein.

We all know what sweet, salty, sour and bitter taste like. But what does umami taste like?

Stein: Umami is the taste of glutamate, an amino acid found throughout the human body and in protein-containing foods. Glutamate elicits a sensation which is often described as brothy, full-bodied, meaty and savory.

Examples?

Stein: Think of chicken broth, a ripe beefsteak tomato or Parmesan cheese. Other foods that have high concentrations of glutamate include miso, peas and human breast milk.

Not all of us may "get" the taste of umami, but everybody seems to have a "sweet tooth." Why?

Stein: Almost all humans like sweet. This is probably because the brain associates sweet taste with energy for the body. Taste can also signal danger, as many poisons taste bitter.

Why wouldn't one of the tastes be spicy hot, as in jalapeno peppers? What's that taste called?

Stein: That's not a taste. It's a separate chemo-sensory system.

Reed: We would call that a chemical irritation.

Why does one person love that irritation — or a certain food, for example — while another hates it?

Reed: That's probably due to genetics, but the exact nature of those genetics is not understood.

What accounts for differences inside of taste categories? For example, you have two people who like sweet things (and who both think raisins are sweet), and yet one hates raisins and the other loves them.

Reed: One person may like the smell of raisins, where someone else does not. The second issue is while both people may like sweet, there is a difference in the preferred concentration of that sweetness.

Can it also be caused by psychological associations, bad experiences, shape, texture, etc?

Reed: Absolutely.

Do animals have taste buds?

Stein: Of course, animals have taste buds.

Then why aren't most dogs discriminating? They eat some disgusting things.

Stein: Dogs are omnivores. They have evolved to eat just about anything.

What about cats? Why are they more picky?

Reed: Cats cannot taste the sweet taste. They actually have a defect in their sweet taste receptor that keeps them from detecting sweet.

So what is an "acquired taste," and why do some people seem to acquire a taste for, say, coffee or beer, while others don't ?

Reed: People acquire a taste for it because they appreciate the drug effects of coffee or beer. But not everybody finds the drug effects to be worth the bitterness of the caffeine or the sting of the alcohol.

But our tastes can change, right?

Stein: Taste sensitivity and food preferences may change across the lifespan, extending from infancy through old age, in ways we don't yet completely understand. Children appear to be more sensitive to some tastes than their parents, suggesting that kids and parents may live in different sensory worlds.

Reed: Just like our eyesight changes as we get older, our taste changes, too.

Can that change in taste go both ways? Liking something we didn't like and hating something we used to love?

Reed: Of course.

There's a huge, warm cinnamon roll just out of the oven sitting on the table. It smells unbelievable, and your mouth starts to water. Is that the work of your taste buds?

Reed: (Laughs) That's your brain at work. It's getting the enzymes in your mouth ready. It's preparing your body for the event to come!

Mmmm. I think we need to get ready for that event right now. Thanks for the time.

———

MANUFACTURED SWEETNESS

Onefactor that contributes to how food tastes to you is the taste buds' sensitivity. Here's a test you can try at home: Before eating anything in the morning, take a bite out of a nice, sweet, ripe banana. Then put it down and take a bite out of a sweet candy bar. Chew it well, making sure it spends a lot of "face time" with your tongue. Then spit it out, and take another bite out of that banana. Interesting how it tasted sweet a moment ago, but now it tastes like cardboard. What this demonstrates is how your taste buds can be desensitized. If day after day, year after year, you eat foods that are loaded with refined sweeteners, you won't be able to enjoy the natural sweetness of nature's candy: fruit.

—Don Bennett, Health101.org

SMOKERS TASTE LESS

Smoking dampens the ability to taste. In a study published in August, researchers used electrical stimulation to test the taste threshold of 62 Greek participants. Applying an electrical current to the tongue generates a unique metallic taste. Measuring the amount of current required before a person perceives this taste enables researchers to determine taste sensitivity. The 28 smokers in the study scored worse than the 34 nonsmokers. The researchers then used endoscopy to measure the number and shape of a type of taste bud called fungiform papillae. They found that the smokers had flatter fungiform papillae, with a reduced blood supply.

—"BMC Ear, Nose and Throat Disorders"

SENSITIVE SUPERTASTERS

Supertasters, which make up about a quarter of the population, are more sensitive to bitter, taste sweet more sweetly and experience the burn of hot peppers at nearly twice the intensity of others . In one instance, a regular taster had 11 taste buds per square centimeter while a supertaster had 1,100. It made sense, then, that supertasters felt more pain when they ate chili peppers, because pain receptors in the mouth are wrapped around taste buds.

—Linda Bartoshuk, professor of Otolaryngology and Psychology, University of Florida

TONGUE GEOGRAPHY

The tasting ability of the tongue is definitely geographic. The front two-thirds of the tongue carry a small number of tiny bumps called fungiform papillae, but each of these contains just a few taste buds. Toward the side and back of the tongue are a few linear ridges called foliate papillae, and these contain dozens to hundreds of taste buds. The true taste sensation is found at the very back of the tongue, where three large nodes called circumvallate papillae contain a whopping 2,400 individual taste buds. But that's not all, folks. There are another 2,400 taste buds sprinkled throughout the throat. Taste buds in your throat? That's right. It's one more reason to swallow carefully. ... Taste buds themselves are an onion-shaped collection of taste-receptor cells. Instead of green shoots, tiny hairs called microvilli extend up into the pore of each taste bud to help interrogate whatever morsels fall in.

—Craig Bowron, Minnesota Monthly