If you've ever regretted ordering a spicy meal, take note: A new study identifying molecules that suppress the heat of chili peppers hints at the possibility of adapting these compounds into an "anti-spice" condiment for food that's too fiery to eat.
The research helps explain differences in chili pepper pungency, or spiciness, by identifying three compounds in a range of pepper samples that chemical analysis predicted, and study participants on a tasting panel confirmed, are linked to lower heat intensity.
The findings have multiple potential applications: customized chili pepper breeding, a pain-relief alternative to capsaicin and, in homes with a range of culinary spice sensitivities, a new condiment to put in the pantry.
"If you're at home and you've ordered cuisine that has spice to it that's a little too hot for some tastes, you can just sprinkle on a form of chili pepper that has got these suppressant agents in them that will dial it down," said senior study author Devin Peterson, professor of food science and technology at The Ohio State University.
"I think the idea of using a natural material as an anti-spice, especially for somebody with kids, would have value as a household ingredient."
The research was published online May 14 in the Journal of Agricultural and Food Chemistry.
Chili pepper heat intensity has long been attributed to two members of a class of compounds called capsaicinoids: capsaicin and dihydrocapsaicin. Scoville Heat Units, a scale used for over a century to determine the pungency of chili peppers, are calculated based on each pepper's concentration of these two compounds.
For this study, Peterson and colleagues obtained 10 cultivars of chili peppers, determined their Scoville units based on their capsaicinoid content, and normalized the group so all samples, prepared in dried powder form, had the same number of Scoville units. The researchers then added the standardized powders to tomato juice and asked a trained tasting panel to gauge their pungency.
"They're all in the same base and all normalized, so they should have had a similar heat perception, but they didn't," said Peterson, also faculty director of Ohio State's Foods for Health Research Initiative. "That is a pretty clear indication that other things were at play and impacting the perception."
With this sensory perception data in hand, the researchers created statistical models and consulted molecular structures in existing libraries of chemicals to arrive at five candidate compounds predicted to be lowering the peppers' perceived spiciness.
A second trained panel of tasters then compared the pungency of a range of capsaicinoid samples mixed with varying levels of these candidate compounds during tests in which different samples were placed on each side of the tongue simultaneously.
The second round of sensory results combined with high-resolution mass spectrometry and nuclear magnetic resonance experiments led the team to narrow down the heat suppression effects to three compounds: capsianoside I, roseoside and gingerglycolipid A. These results describe an overall mechanism that affects chili pepper heat levels, but are not exclusive to any specific chili pepper varieties.
Peterson's lab studies the complex relationships between oral cavity receptors and food compounds that influence human perception of flavor. The broad goal: applying findings to improving the taste of healthful foods without adding sugar, salt and fats.
"What is maybe underappreciated from a science perspective is how important food flavor is to your dietary patterns and your enjoyment in life," he said. "So part of what we focus on is, how do we make healthy eating less difficult?"
When it comes to capsaicinoids, however, there is also a pain management implication from this study's results.
The TRPV1 receptors in the oral cavity that perceive chili pepper spiciness are triggered by molecules - including capsaicin - that cause sensations of pain and heat. These same receptors are present throughout the body, meaning that capsaicin in supplement and topical form eases pain by initially exposing receptors to the irritation signal and eventually desensitizing them to that stimulus so the pain goes away.
The newly identified heat-suppressing compounds may have the same desensitization effect - without the initial burn, Peterson said.
This work was supported by the Flavor Research and Education Center, which Peterson founded and directs, in Ohio State's College of Food, Agricultural, and Environmental Sciences. Joel Borcherding, former graduate student, and Edisson Tello, research professor, both in Ohio State's Department of Food Science and Technology, co-authored the study.
