Virginia Utermohlen on Taste Sensitivity
Virginia Utermohlen is an associate
professor of nutritional sciences at Cornell University, where she studies individual
differences in taste and smell sensitivity and how those differences relate to our
personality and ability to perform.
Do different people taste things
differently?
Yes, there are genetic variations all over the place. We have differences in the
taste buds and the trigeminal nerve, plus people differ in their saliva, which
influences taste. What I taste and what you taste in the same food is going to be
different.
One difference is sensitivity to 6-n-propylthiouracil (PROP). People are genetically
capable or incapable of tasting it. Certain populations such as the Sub-Saharan Africans
tend to be very sensitive to it, and then there are populations in Europe where
insensitivity is very common. The British are famous for simple flavor systems and they
tend to be fairly insensitive tasters, whereas if you look at the flavors in Asian,
Sub-Saharan African, and indigenous American cuisines, those people are highly sensitive
tasters and their foods have complex flavor profiles.
The trigeminal nerve senses hot and cold, pain, texture, and to some extent sweet,
independently of the taste bud cells. Compounds like menthol bind to the same receptor
that changes shape in response to cold temperatures, so the brain interprets what
menthol is doing as cooling, even though it’s not colder than anything else around.
Similarly with capsaicin: it binds with the receptor that changes confirmation with warm
or hot temperatures so the brain says, “This is hot!” It really isn’t hot, but the brain
interprets it as that. There are differences [in trigeminal sensitivity] from one
individual to the next. Some people will put an Altoid on their tongue for the first
time and think, “This isn’t bad!” Another person puts one on their tongue and thinks
it’s got to get out of there as soon as it can. Once those trigeminal nerves get
overactivated, it’s painful. Another thing that the trigeminal nerve senses is pungency.
French cheeses are very pungent.
Is there something about the French that causes them to like
pungency in cheese?
In my rather small sample, the people of French descent tend to be more sensitive to
the cooling sensation from mint. So on the average my guess is that they would be more
trigeminally sensitive.
If the French tend to be more trigeminally sensitive, it
seems like they would be more sensitive to the pungency in cheeses and thus not like
them very much.
This is something important and interesting: if you are sensitive to something, it
can be either adverse or pleasant. Now pungency, in my opinion, is not aversive. Some
people think it is. I personally like chocolate that’s quite bitter. Just because
something has a quality doesn’t mean it’s aversive or pleasant. That varies from person
to person.
Something you said makes me wonder about beer and wine, and
low trigeminal sensitivity versus high trigeminal sensitivity.
The carbonation and pungency of beer give it a trigeminal kick. If you are sensitive
to the pungent, the trigeminal side of things, but not sensitive to the bitterness of
beer, you’re going to like beer a lot better than I do. I can’t stand it!
So could one take a PROP test strip and a menthol candy and
between those two things figure out which a person likes more, beer or
wine?
That’s possible. I’ve never done that experiment before.
Dr. Utermohlen had previously explained to me that individuals who define
“reasonable” as “logical” are generally less trigeminally sensitive and those who
define it as “justifiable, fair” tend to be more trigeminally sensitive. Note that
trigeminal sensitivity is a separate phenomenon from PROP
sensitivity.
We talked about how people define the word “reasonable” in a
previous conversation. Why would somebody who is more trigeminally sensitive define
reasonable as fair?
Well, here is my hypothesis—not that I necessarily have any proof of this—but taste
and smell go to the orbitofrontal cortex, which is the part of the brain that is
critical in evaluating whatever you experience. That’s its job: to
evaluate whether something is good or not.
When you reason something through, it’s another way of getting
at whether something is good or not. Logical reasoning makes use primarily of another
part of the brain called the dorso-lateral prefrontal cortex. That part of the brain
gets no input whatsoever from taste and smell.
Which way you decide to think something through will depend
on which way you decide how something has value. It depends on whether you go to the
that-smells-fishy-to-me sort of evaluation versus a logical evaluation.
Does this mean that when people talk about making decisions
from their gut versus logical decisions, they’re making decisions with their
orbito-frontal cortex versus their dorso-lateral prefrontal cortex?
Yeah. I think so. I really do.
What about geeks?
In my experience, geeks are very mixed in their sensitivities. In our data, the more
mathematically oriented computer scientists tend to be on average nontasters. The
computer scientists who are more interested in the purpose of a program tend to be more
sensitive tasters. One group of geeks will be creative in ways that are highly logical
and scientific. That other crowd, however, will be interested in emotion and expression
and look at programming in a holistic way. That crowd will “get it” when you ask them if
sunsets or the crackle and flame of a wood fire spark their imagination.
Wait, what’s this?
Some of the questions that we ask have to do with a phenomenon called
absorption, the capacity to become completely immersed in a
sensory experience. On the average, from the data we have, people who are moved by a
sunset, or for whom the crackle and flames of a wood fire spark the imagination or may
produce visual images are highly trigeminally sensitive.
I believe that people who have a high capacity for absorption should imagine what a
dish would be like, and then work toward it by maybe adding a pinch of this or that,
tasting as they go. They should really spend time experimenting at what the differences
in tastes are like, and not be religiously bound to a recipe.
And the other type?
The other type might stick to a recipe, because they are probably going to have
better success if they follow A, follow B, follow C, follow D, and the thing will come
out. It requires less guesswork, and so is less dependent on a person’s
sensitivity.
