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Eye on Psi Chi: Spring/Summer 2013
The Enhancement of Sweets
With Dr. Linda Bartoshuk

Bradley Cannon, University of Tennessee at Chattanooga

Have you heard that sugar-free sweets may not be as healthy as you thought? Fear not, Dr. Linda Bartoshuk has collaborated with colleagues in horticulture to increase the palatability of fruits and vegetables. That work led to a new way to sweeten foods and beverages, which may reduce dependence on sugar and artificial sweeteners. Will sugar enhancers replace artificial sweeteners? Dr. Bartoshuk tells us all about it, plus she explains how you can tell if you are a supertaster and more.

As a woman, what was your most challenging moment getting through college in the 50s?

College wasn’t that bad, because Carlton College faculty were very sensitive about female students. But when I got to graduate school at Brown, I wanted to work with Dr. Carl Pfaffmann who refused to let me in his lab. This shocked me, and his male students wouldn’t have it. They thought it was unfair, and one of them taught me what to say and how to do a preparation that Pfaffmann
 was famous for. In return, Pfaffmann quite wrongly developed the impression that I was unusual for a woman because I was quite aggressive and insistent. He liked that, so he took me into the lab.

After I graduated, I gave a talk at Brown, and the female graduate students wanted to know how bad it had been when I was there. The interesting thing is that I didn’t perceive these problems at the time. It was true that there weren’t very many women in science and math classes, but at that time I perceived that to be choice.

What has been the most beneficial project that you have taken part in?

It probably was the discovery of supertasters, where I found out that our technique of measuring sensations was not giving us valid comparisons. That’s when I realized that we had to do it better. For example,
if you’re in the hospital, a nurse will ask
you how much pain you are in on a scale from 0 (no pain) to 10 (most intense pain
 you have ever experienced). If you feel your pain decrease from seven to two, that’s a legitimate comparison. That means that
your pain did decrease. But what happens
if the nurse compares your numbers with someone else’s? Is that legitimate? No, because we don’t know what 10 means to each of you. We have no idea if you’ve been in much worse pain than your roommate, and that makes the comparison meaningless. I realized that this was true about taste too. There must be differences here as well, and we have to be able to make a legitimate comparison.

Since then, we have learned that a supertaster (e.g, someone with sixty fungiform papillae in a 6 mm circle on the tip of the tongue) lives in a neon food world compared to someone with fewer fungiform papillae (e.g., five in the circle) who lives in a pastel taste world. As a psychologist, what really interests me is that food behavior between these people is not the same. For one thing, supertasters have much more extreme likes and dislikes. If we ask a supertaster and someone who is not a supertaster to rate how much pleasure they get from their favorite foods and how much displeasure they get from their least favorite foods, the supertaster will give much more extreme ratings. We’re now studying other things, and it looks like this is going to be true about some emotional experiences as well.

How can we find out if we are 
supertasters or nontasters on our own?
One thing you can do is put blue food coloring on your tongue. Fungiform papillae are the round structures on your tongue that will not pick up the dye, so suddenly you will have either light blue or pink circles on your tongue. Use a template of a six millimeter hole—the size of a paper punch. You lay
that hole on the tongue, so that the edge of the hole touches the tip, and you count how many you see. The more fungiform that
you have correlates with taste intensity. My daughter is at the extreme end with only five fungiform papillae’s in that circle. One of the best supertasters that I’ve encountered had sixty. It’s a very big difference, and you can see it if you get a bunch of people and stain their tongues and look at them.

There are obvious evolutionary advantages and disadvantages in being a supertaster. However, your studies show that more women are supertasters than men. What could be some of the reasons for this?
The minute you hear that women are supertasters, you think, "ah!, it protects
the fetus,” because bitter tastes tend to be a signal for poison. So you could argue that supertasting women have an advantage because they can help protect a fetus better by avoiding poisons, but I don’t know if that’s true or not. Picture a Neanderthal tribe moving into a new area where they don’t know what’s safe to eat. I imagine the chief sending his wife out because she is a supertaster, so she tastes the bad plants as bitter and warns the rest of the tribe. Now did this ever really happen? Heaven knows, but it helps you see what a difference being a supertaster or not could make.

There are a couple other cases too. For example, pellagra is endemic in areas of South American. One of the things that you can do to stave of pellagra is to drink very strong coffee, because the ingredients in coffee metabolize into the niacin that you are missing. If you look into these areas, you will discover more nontasters than you would expect, because these are the people who
can take the bitter coffee. In another area
in South America, plants are goitrogens—meaning that your health is impaired if 
you eat them. In that area, there are many supertasters, because they were able to avoid these plants.

How is the new idea of sugar enhancement different from an artificial sweetener?
Odors get to your nose in two ways. You sniff them and they come through your nostrils by orthonasal olfaction. Or you put food in your mouth and the volatiles are forced up your nose from the back of the throat through retronasal olfaction. The brain treats the two routes differently. It sends orthonasal olfaction to one part of the brain, and retronasal olfaction to another, combining it with taste. When retronasal olfaction and taste come together to form flavor, they can enhance each other through circumstances, which we are trying to understand.

We did a study on tomatoes with Harry Klee who planted 80 different heirloom tomatoes. What was interesting was that some of the tomatoes were sweeter than the sugar content would have predicted. We did multiple regressions, and it turned out that some volatiles—aka the simple gaseous odor in the tomatoes detected through retronasal olfaction—enhance sweetness. The more of those volatiles that are in a tomato, the sweeter that tomato is. Other volatiles can suppress sweetness.

All of a sudden we were uncovering these volatile effects that we didn’t know were operating in fruit. Then we wondered if we can take these volatiles out of a fruit and put them in something else so that they’ll enhance a flavor, and it looks like we can. A mixture of the correct volatiles with a small amount of sugar will produce a much stronger sweet. In that way, we wouldn’t be using it as a substitute sweetener. We’d be using it to intensify the sugar that’s already there.

What can we expect from you in the future?
The commercial implications of finding a completely safe sweet enhancer are very important to the university. Imagine if we could give you some kind of syrup to add to something with a really bad taste, and the bad taste would go away. We know that sweet inhibits bitter really well. We think that’s going to be another direction to go in.

For the next few years, my job will be to get the basic research done that will tell us the properties of this effect and whether it will work in certain applications. If this is true, of course we all dream that it’s going to be the next Gatorade, which made a fortune for the University of Florida. Wouldn’t it be great if this enhancement of sugar did the same?

Now, is it a good idea to enhance sweet taste? That’s another thing that should be examined. You know there is new research suggesting that artificial sweeteners don’t help us lose weight at all. In fact, you gain weight with them. This is work done by Swithers and Davidson at Purdue, and it’s really good work. So is producing the sensation of more sweets with volatiles going to be a good thing? We don’t know. But the point is that we can find out.

What advice can you give an up-and-coming woman interested in math or science today?

Many people have given me practical advice, such as, "Well, it would be better if you did this thing or the other.” But frankly, I don’t think any of that paid off. What I think is important, is that you do something you love. Go with your heart. If you’re doing work that you love, whether you’re wildly successful or not, at least every day is an adventure, and that is something wonderful.


Dr. Linda Bartoshuk, Bushnell Professor at the University of Florida, is director of Human Research for the UF Center for Smell and Taste, and has been elected to the Society of Experimental Psychologists, American Academy of Arts and Sciences, and the National Academy of Sciences. Dr. Bartoshuk is past president of EPA, Divisions 1 and 6 of the American Psychological Association, the Association for Psychological Science, and the Association for Chemoreception Sciences. Besides her most recent work on sugar enhancements, she and her students have studied genetic variation in taste as well as patients with taste disorders (using anesthesia to simulate these disorders in normal controls). Older psychophysical methods (category and VAS) were not designed to compare different groups of individuals; Dr. Bartoshuk and her students needed such comparisons (e.g., patients vs controls) and so developed new sensory and hedonic scaling tools that could provide them.

Copyright 1996 (Volume 1, Issue 1) by Psi Chi, the International Honor Society in Psychology

 

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