What makes chili peppers so hot?
The spicy science of capsaicin and receptors on your tongue.
Vocabulary: receptors, capsaicin, nerves, tolerance
Like many spice junkies, Dr. Marco Tizzano once believed he could develop a tolerance to the burning, painful sensations generated by eating chilis. But as a chef and researcher in chemosensory sensations, he now knows better. In this Science Friday video, Dr. Tizzano explains how capsaicin creates a chemical cascade inside your body and why emotions might make chili lovers think they can handle the heat.
Questions for Students
- Compare your experience eating something spicy to the reactions of people in the video. Where in your mouth do you feel the sensation of spicy foods?
- Explain what Luke Groskin refers to as the “chemical cascade” as it relates to capsaicin and TRPV receptors.
- Dr. Tizzano has quite a few varieties of peppers in his kitchen. Do you think that the origin of the peppers influences how they affect the eaters? Why or why not?
- Why do you think the body would internalize or cover receptors instead of desensitize them? What advantage could that give to someone?
- Design an experiment to test the premise introduced by Tizzano: people who like hot peppers and people who do not like hot peppers have no difference in how they perceive the pain. Think especially about the variables you would need to control. How would you establish a standard way for participants to describe spiciness?
- In our follow-up audio segment, Ira Flatow interviewed Paul Bosland, Director of the Chili Pepper Institute at University of New Mexico. He described five different hot pepper species. Have students look at this collection of spice profiles and this article that discusses country of origin of different peppers. Analyze whether trends emerge between flavor profiles and region of origin.
[Check out this article on the hottest pepper in the world, the Carolina Reaper.]