Bite into a fresh mint leaf and, in addition to the minty flavor, there’s a distinct cooling effect, like chilly water on your tongue. Mint-flavored gum and candies, even more so. How does that work?
Science
Why Does Mint Make Our Mouths Feel Cold? Ask Paul
How chemistry tricks us into feeling like we’ve downed ice cream or a frosty drink.
By Published Mar. 27, 2024.
Why Mint Makes Our Mouths Feel Cold
Mint works just like chile peppers do, tricking us into thinking we've eaten something hot or cold.
When you put a chile in your mouth, the compound capsaicin, which abounds in peppers, triggers particular receptors on your tongue. Known as TRPV1, these receptors are responsible for signalling when we’ve eaten something physically hot, like the first sip of tea.
But the shape of the capsaicin molecule allows it to activate the receptors, sending a “hot” message to our brains even though the stimulus is just chemical, not physical like heat. This phenomenon is known as chemesthesis.
Mint plants such as peppermint (Mentha piperita) produce menthol, a terpene compound with characteristic mint flavor. But, just as capsaicin activates TRPV1, menthol activates a neural receptor called TRPM8, which is primarily responsible for detecting cold temperatures. Menthol fools our tongues into sending a message to our brains saying “That’s icy cold!”
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Why Mint Gum Makes Our Mouths Feel Especially Cold
Mint gum sometimes uses menthol for its cooling effect; or sometimes derivatives of menthol that pack a stronger cooling punch. Many such synthetic compounds were developed by the skin-care industry, to give a refreshing cool sensation to shaving creams and shampoos. (The most powerfully minty compound, icilin, is about 200 times more cool and refreshing than menthol. As far as I know, it's not used in any commercial products.)
Some gums and candies also add sugar derivatives known as sugar alcohols. These are low-calorie, low-glycemic-index sweeteners—but some of them, such as xylitol and erythritol, have a bonus effect. When they dissolve in the mouth, they absorb a significant amount of heat, producing a cooling sensation. Unlike menthol, though, the process of sugar alcohol crystals dissolving in water literally lowers the temperature of your mouth. Pretty cool!
