Spicy foods taste spicy because they contain a family of compounds called capsaicinoids. Capsaicin is the major culprit. It’s found in chillies, jalapeños, cayenne pepper, and is even the active ingredient in pepper spray.
Capsaicin doesn’t actually physically heat up your mouth. The burning sensation comes from receptors in the mouth reacting to capsaicin and sending a signal to the brain that something is very hot.
