Peppers are hot due to the chemical compound capsaicin, which is found mainly in the white membrane or placenta inside the pepper, not in the seeds as commonly believed. Capsaicin binds to heat and pain receptors in the mouth and other tissues, sending signals to the brain that simulate a burning sensation, even though no actual burn occurs. This sensation triggers the feeling of heat or spiciness when eating peppers.
Capsaicin serves as a protective agent for the pepper plant by deterring insect damage and fungal growth, and it affects mammals by causing the burning sensation but does not affect birds, which helps in seed dispersal. The heat level of peppers is measured on the Scoville Heat Unit scale, with pure capsaicin rating the highest.
To summarize:
- Hotness comes from capsaicin, mainly in the placenta inside the pepper.
- Capsaicin activates pain and heat receptors, causing the burning sensation.
- The heat is measured by the Scoville scale in heat units.
- Capsaicin protects the pepper plant from insects and fungi.
- The seeds themselves do not contain capsaicin.
- Birds are immune to capsaicin, unlike mammals.
