What is the science behind flavor?

Bob Holmes is author of “Flavor: The Science of Our Most Neglected Sense.”
Bob Holmes is author of “Flavor: The Science of Our Most Neglected Sense.”Ben Holmes

If you ask people to describe an apple sitting in front of them, chances are they will have many words to explain its color, shape, pattern, and texture. They could also likely tell what distinguishes that apple from a very similar one. Ask for details about its flavor, though, and the conversation might be much shorter. For many, flavor remains a vague subject.

Science writer Bob Holmes takes a deep dive into the details behind this important sensory experience in “Flavor: The Science of Our Most Neglected Sense.” Writing the book took Holmes from commercial flavor laboratories in Cincinnati to kitchens at the Culinary Institute of America as he sought a better understanding of this vast sensory world. “There’s a lot of unsettled science there,” Holmes says.


Q. Are flavor and taste really the same thing?

A. The funny thing is that the English language doesn’t help us out there because we have one word, “taste,” to mean taste in the strict sense, which is sweet, sour, salty, bitter, umami — the five and maybe a few more things we actually taste with our tongues. But we also talk about “tasting” wine, which is about the whole flavor.

Q. What’s the difference?

A. Flavor is mostly the senses of smell and taste, plus a little bit of what I call mouthfeel — temperature and texture, the burn of chiles. Flavor is really the composite thing that the brain puts together from all those different inputs. When we have a cold, we say “I can’t taste anything,” when in fact the exact opposite is true. Taste is the only thing you’ve got because you’re not smelling.

Q. You mention that there might be other basic tastes. What did you find about those?

A. It’s pretty clear now that there is a taste for fat — actually for fatty acids, which are the break-down products of fats that add funkiness to aged meats and aged cheeses. There may even be basic tastes for things like calcium. Carbon dioxide is one that’s been suggested. I’ve even read that some people are suggesting that there might be a basic taste for water.


Q. Why is there less science on taste and smell than other senses?

A. They’re the poor cousins of our senses. If you ask almost anybody “which sense would you like to lose, if you had to lose one?” almost everyone would pick smell. Vision and hearing seem like the frontline senses. They’re the ones that have gotten the most research attention. Actually, people don’t know how we detect odors at this point. There’s still controversy about the basic details of how we detect them. It’s pretty clear that you have at least tens of thousands and maybe millions or billions of different odorous molecules that somehow we can detect and discriminate between. It’s a harder job.

Q. We hear about supertasters. Do they enjoy food more than other people?

A. You get this word supertaster and it’s like Superman. It sounds like this wonderful ability. It’s basically someone who’s more sensitive than the norm to oral sensations, to tastes, to the burn of hot pepper. They’re more sensitive to bitter tastes, to sweets. In practice, what happens is a lot of supertasters perceive such intense sensation that they don’t like it. Supertasters tend to have kind of narrow diets, bland diets, to avoid that over-intense flavor.


Q. You did an experiment where you ate without tasting. What was that like?

A. It was odd. If you want to see what it’s like to be without the sense of smell, it’s easy. You pinch your nose. There’s no way to take away taste easily in the same way. There’s a mouthwash called chlorhexidine. It knocks out the taste of salt for a half an hour or so. There’s a tea made from a South American plant that will knock out the taste of sweet. We knocked out both and then ate a hamburger. It was miserable. It was like eating Styrofoam. The interesting thing was that the French fries were a little bit OK, probably because of the mouthfeel of the fat and umami from the ketchup.

Q. How do factors beyond senses influence flavor?

A. There have been studies that look at what happens if you tell someone that a wine is more expensive. You give people the same wine twice. Once you tell them that it’s a $10 bottle and once you tell them it’s a $90 bottle. They like it better when they think it’s a $90 bottle. They’ve actually measured brain activity while they do it. They’re not just saying that. The pleasure centers of the brain light up more when they think it’s a $90 bottle. They are truly enjoying it more.

Michael Floreak can be reached at michaelfloreak@gmail.com