How can you tell how hot a pepper is without eating it first? A family of chemical compounds called capsaicinoids create the hot, burning feeling in your mouth and are mostly concentrated in the white lining of a pepper. The most abundant member of this family that is found in hot peppers is a compound called capsaicin. When you bite into a hot pepper or eat spicy foods, the capsaicin attaches to heat-sensing receptors in the mouth, releasing chemical messengers known as neurotransmitters that travel to the brain. These neurotransmitters trigger a false alarm that your mouth is on fire. It’s a bodily response that can produce sweating and watery eyes but does not cause physical harm.