What makes chili peppers hot?
Chili peppers are hot because they contain capsaicin, a chemical that triggers pain and heat receptors in the mouth. Your brain reads the signal as burning, even though no real heat is involved.
Capsaicin binds to a receptor called TRPV1, which normally responds to real heat above about 43°C. That is why spicy food feels hot and can make you sweat, flush and reach for a drink. The receptor was identified in 1997, and the discovery contributed to a Nobel Prize in 2021.
Most of the capsaicin is in the pale ribs, or placenta, inside the pepper that hold the seeds, not in the seeds themselves. Removing the ribs makes a pepper much milder.
Why water does not help
Capsaicin is an oil-like compound that does not mix with water, so drinking water spreads it around. Milk, yogurt and other dairy products work better because a protein called casein helps carry capsaicin away. Bread or rice can also help.
Did You Know?
Capsaicin is used in medical creams and patches to relieve some kinds of muscle and nerve pain, because repeated exposure can make pain receptors less sensitive.