A pepper's pungency is caused by capsaicin (pronounced cap- say-i-sin), a chemical that is odorless, colorless, and flavorless, but that irritates any tissue it contacts. Biting into a pepper stimulates nerve receptors in the mouth to signal “pain,” and the brain in turn induces sweating, salivation, and increased gastric flow in an attempt to rid the body of the irritation.
Capsaicin is related in structure to vanilla (structurally, it is the vanillyl amide of isodecylanic acid), but it is very acrid. A single drop diluted in 100,000 drops of water will produce a persistent burning of the tongue. Diluted in 1 million drops of water, it still produces a perceptible warmth.
Capsaicin is concentrated in the pepper's placenta, the inner part that supports the seeds. There is a rough correlation between the amount of capsaicin and the amount of carotenoid pigment. Thus, the stronger the flavor, the deeper the color of the fruits.
Capsaicin has many uses of its own. Applied in concentrated form to the skin, it induces a feeling of warmth (actually an irritation), and because of this it is used in sore-muscle remedies. It is also the ingredient that gives the “bite” to commercial ginger ale and ginger beer. It is so powerful an irritant that it is used to make antidog and antimugger sprays. Also, it is used in concoctions to deter deer and rabbits from devouring vegetable crops.
Recently, it has been found that the brain probably releases painkillers when nerve receptors send it the “capsaicin signal.” It has been tested in topical treatment for relief of pain caused by shingles, psoriasis, and other skin conditions.
In another modern twist, capsaicin and peppers are being touted for the diet conscious. Peppers, it is said, perk up the taste of food without adding fat. Indeed, it is thought that they may burn more calories than they provide.
Wild Andean Peppers. 6 In the peppers' probable “homeland” in Bolivia are two essentially undomesticated species, known as “ulupicas,” both of which are greatly appreciated by the local peoples.7 They are aromatic, tasty, and much hotter than rocoto or other common peppers. As the Indian name implies, they are closely related to one another, and perhaps to rocoto. Both have purple flowers or, occasionally, white flowers.