Some Like it Hot

When it comes to food choice, Nadia Byrnes is something of a natural. “My friends always joke that when they need a new place to eat they don’t Google it, they just ask me,” says the Penn State doctoral student. “My bucket list is restaurants.”

Not exactly a surprise, then, that Byrnes eventually landed in the laboratory of John Hayes, assistant professor of food science. Hayes, who also directs the University’s Sensory Evaluation Center, is interested in why people eat the foods they do. He approaches this complicated question from the relatively fresh angle of sensory science.

“Technically, it’s a subset of food science,” Byrnes explains, “but it has roots in neurobiology and psychology as well.”

plate of Indian curry with plates of rice and naan in the background
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Byrnes examined the possible relationship between the love of capsaicin, chili’s active ingredient, and aspects of personality. She presented her preliminary results this spring at Penn State’s annual Graduate Research Exhibition.

A self-described “science dork” who majored in chemistry at the University of Rochester, Byrnes discovered food science through the Food Network on television—“It was Good Eats, with Alton Brown,” she says—and wound up earning a master’s degree in the subject at Ohio State. But while in Columbus she realized that traditional food science, which she describes as “applied chemistry and microbiology,” was not her cup of tea. When Hayes invited her to come to Penn State for her Ph.D., she jumped at the opportunity.

Applied sensory testing at Penn State dates back to the early 1970s, but the University invested anew in sensory science in 2006 with the construction of the Sensory Evaluation Center as part of a new Food Science Building. The Center is a state-of-the-art testing facility used for both industry trials of new food products and cutting-edge research. When Hayes was hired in 2009, he became the first tenure-track faculty member in sensory science.

Hayes’ work explores variations in individual taste perception, with recent studies showing biological differences in people’s abilities to taste salt and judge the qualities of wine. In 2011, he embarked on a large multiyear project aimed at sorting out the welter of genetics, biology, and personality factors involved in chemesthesis, or what he calls “all the non-taste stuff that goes on in the mouth.”

The tingle of carbon dioxide, the cooling of menthol, the astringency of red wine are all chemesthetic sensations. But the most powerful of these oral stimuli, and the most puzzling, has to be the burn of chili peppers. Why do some people adore the searing heat of a vindaloo curry, while others avoid even the slight warmth of pepperoni? As a part of Hayes’ larger study, Byrnes examined the possible relationship between the love of capsaicin, chili’s active ingredient, and aspects of personality. She presented her preliminary results this spring at Penn State’s annual Graduate Research Exhibition.

Earlier researchers have looked at the psychology of spicy food, Byrnes notes. In the 1970s, Paul Rozin at the University of Pennsylvania, after studying the eating habits of Mexican children, concluded that the Mexican love of chili is a learned behavior. It was Rozin, too, who coined the term “benign masochism” to explain why a person would develop an affinity for the “biologically aversive stimulus” of a mouth that feels like it’s on fire. To him it seemed akin to the thrill of gambling or riding a roller coaster, slaking a desire for new and slightly dangerous sensations.

smiling young woman in lab coat, Food Science Researcher Nadia Byrnes
Patrick Mansell

Nadia Byrnes

Hayes and Byrnes wanted to push that insight even further. Could measurable personality characteristics like sensation seeking, or sensitivity to punishment or reward, be linked to a love of spicy food?

In the context of her research, Byrnes explains, sensitivity to punishment tends to mean aversion to novelty, while sensitivity to reward translates as impulsivity. (“These are people who will go after the reward regardless of the punishment,” she says of the latter.) Sensation seekers may be pursuing either intensity of experience or novelty, or both.

Burn intensity is another important variable. Are the people who most dislike chili’s heat simply the ones who feel it most? To gauge individual variability, Hayes’ team gave out sample cups of water spiked with mounting concentrations of capsaicin.

“We expected that subjects who reported liking the burn would eat more spicy food,” Byrnes says, “and that’s what we found. We also expected those who reported eating more would have lower burn intensity, but we didn’t find any evidence of that.” The discrepancy may be due to variation in subjects’ own definitions of what constitutes spicy, she concedes, “but even without taking into account the possible differences in the actual grams of capsaicin ingested, we found some interesting relationships between personality traits and liking of spicy food.

“We expected the sensation-seekers to rate spicy meals higher, for example, and they did. But there was variation in their responses depending on the type of spicy meal. Some people like Asian cooking—which may include capsaicin but has other chemesthetic ingredients, too, like ginger and Wasabi—yet they don’t like chili barbecue. Why do they like one type of spicy and not another?”

Perhaps predictably, Byrnes reports, sensation seekers don’t seem as sensitive to the heat. “They don’t rate it as intense. And again we’re not sure if that means that biologically they’re not getting as much of a response, or if they’re desensitized, or if they are the type of person who went skydiving the day before, so the burn of capsaicin in relation to the rush of adrenalin doesn’t rate that high.”

There’s still a lot to sort out, in short. “Food choice,” Byrnes stresses, “is a really complex system that takes into account cultural expectations, the physical environment, cost, cravings—and as we’re learning, there may be genetic components, too. It isn’t easy to separate.”

As for her own preferences, “I’m really adventurous with eating,” she confesses with a grin.

“I love spicy food.”

Nadia Byrnes, M.S., is a Ph.D. candidate in food science, nkb5009@psu.edu. Her adviser, John E. Hayes, Ph.D., is assistant professor of food science and director of the Sensory Evaluation Center, jeh40@psu.edu. Byrnes’ presentation, “Determining the relationship between personality variables and liking of spicy foods,” won second place in the Social and Behavioral Science category at Penn State’s annual Graduate Research Exhibition in March 2012.

Last Updated June 27, 2012