The Sound of Science - "Cool Mints and Hot Peppers"

Dec 7, 2018

Kate: Hi there, this is Kate Powers from NIU STEM Outreach, and it’s time for another installment of The Sound of Science on WNIJ. Today I’m joined by Sam Watt, who has another great question from a listener. 

Sam: That’s right, Kate. Today’s question comes from Richard, who asks, “Why do spicy foods make my mouth feel hot, but minty foods make it feel cool?”

NIU STEM Outreach

Sam: Inside our mouths, we have lots of different types of chemical receptors. Taste receptors can react to the sodium or sucrose in foods to sense if what we’re eating is salty or sweet. Other receptors help detect temperature. Some foods contain chemicals that also bind to these temperature receptors, which tricks our brain into thinking we’re sensing hot or cold.

Kate: Exactly. With mints, that chemical is called Menthol. Menthol is able to bind itself onto the receptors in our mouth designed to detect cold. So, when we eat a mint, our brain tells us that our mouth feels cool. But it’s actually just the menthol playing tricks on us.

Sam: So then there must be another, spicy chemical that can bind to the heat receptors, right?

Kate: That’s right. Spicy foods contain a chemical called capsaicin, which can bind to the receptors that detect heat. Again, this causes the receptor to send signals to our brain saying our mouth is hot. But it’s actually just the capsaicin bonding to those sensors, sending a false alarm.

Sam: Now I’ve heard you can rate a pepper’s heat by using something called the Scoville scale. Does this measure capsaicin?

Kate: Sort of. When Wilbur Scoville invented his heat scale, it was based on human feedback to taste tests, so it wasn’t incredibly precise. But since then we’ve developed more scientific ways to measure the exact amount of capsaicinoids in a food. So the Scoville number can give you a pretty good idea of how hot a pepper really is.

Sam: Alright Kate, I have a question for you then. If I eat something spicy and something minty at the same time, will the two effects cancel each other out?

Kate: Well Sam, the research is inconclusive on that one. Some people say that since they’re activating two different receptors, you’d get a weird combination of hot and cool at the same time. Others say that since the effect is in our heads, it would vary person to person I guess you’ll just have to try it for yourself and let us know.

Sam: I’ll do that, Kate. Thanks for the question, Richard! If you have a burning – or cool – question, be sure and send it to We’d love to help you answer it.

Kate: This has been Kate Powers and Sam Watt for The Sound of Science on WNIJ, where you learn something new every day. See you next time!