Capsicum – also known as red or green pepper, Chili pepper, or just pepper in Britain and the US – is a genus of flowering plants in the nightshade family Solanaceae. The fruit of most species of Capsicum contains capsaicin. Capsaicin is an active chemical component that can produce a strong burning sensation in any tissue with which it comes into contact.
Capsaicin and several related compounds are called capsaicinoids and are produced as secondary metabolites by peppers, probably as deterrents against certain mammals and fungi. Pure capsaicin is a hydrophobic, colorless, highly pungent, and crystalline to waxy compound.
Capsaicin is present in large quantities in the placental tissue (which holds the seeds), the internal membranes and, to a lesser extent, the other fleshy parts of the fruits. The seeds themselves do not produce any capsaicin, although the highest concentration of capsaicin can be found in the white pith of the inner wall, where the seeds are attached.
Primarily because of the burning sensation caused when it comes into contact with mucous membranes, capsaicin is commonly used in food products to provide added spice or “heat” – usually in the form of spices such as chili powder, curry and paprika.