Beverly J. Tepper, N’82, N’86, a food science professor at Rutgers University, has been studying taste sensitivity for almost two decades. As an academic who often works closely with the food industry, she is combining food sensory science with nutrition science and psychology to better understand the links between taste, diet and health.
A cornerstone of her work is a compound called 6-n-propylthiouracil, or PROP, a chemical that tastes incredibly bitter to some people, but strikes other people as tasteless. PROP sensitivity had been known as a genetic trait since it was discovered in the 1930s. Statistically, about 25 percent of Caucasians are non-tasters, 50 percent are medium tasters, and 25 percent are particularly sensitive "super-tasters."
Tepper thought that the PROP test could tell her more than how well people could tolerate bitterness. Subsequent research has pointed to a host of taste tendencies that separate tasters from non-tasters.
"We recognized that PROP tasters not only taste the bitterness of PROP and the bitterness of other compounds more, but they perceive sweetness more; they perceive the textural aspects of dairy products more; they perceive hotness—like chili pepper—more," Tepper said. "It’s a whole range of sensory characteristics that they seem to be more sensitive to."
Tepper, however, is looking for a connection that could have larger public health implications: How does PROP taster status affect weight?
Two years ago, Tepper found that women in their 40s who were super-tasters were 20 percent thinner than non-tasters. The super-tasters appeared to eat less overall, be it bitter vegetables or fatty foods.
But there are plenty of exceptions to these rules. Tepper has found one significant factor is food adventurousness, or a willingness to try unfamiliar foods. Another trump card is a person’s ability to fight food urges, called "restrained eating." People’s self-control, particularly if they are concerned about nutrition or their weight, seems to override taster status, so that statistically, it has no effect on body-mass index.
Tepper, who grew up in Boston and studied biology at Northeastern University, was a member of the first nutrition school class at Tufts. After graduating with her Ph.D. in 1986, she completed a postdoctoral fellowship at the Philadelphia-based Monell Chemical Senses Center, a research institute focused on taste and smell research. Her interest in sensory evaluation was born. When a position came up at Rutgers for a sensory scientist in 1989, she took it.
As director of Rutgers’ Sensory Evaluation Laboratory, Tepper often collaborates with food companies. "When I work with industry, usually there is something applied in it that they are interested in and something basic research-oriented that I’m interested in. It’s really a marriage of the two."
Tepper and other PROP researchers are looking at several ways that this one genetic proclivity may affect public health. At least one study has found that heavy smokers are significantly more likely to be non-tasters than tasters, who appear more sensitive to the irritation of smoke and the bitterness of nicotine. Similarly, tasters perceive more bitterness and irritation from ethyl alcohol, and research has found that tasters consume fewer alcoholic beverages per year than non-tasters. Tepper stresses that more work needs to be done in both areas, and that if there is a PROP connection, it would only be a risk factor, not a genetic mandate.
In the future, Tepper believes PROP research will be especially useful in the fight against obesity. Although there have been hundreds of studies looking at PROP status over the decades, only recently has it been recognized for its potential influences on eating behavior and body weight.