Spiciness is not a taste, but rather a sensation that activates nerve endings throughout the body. This sensation, often described as a burning feeling, is triggered by certain chemical compounds found in various foods. It differs from the five basic tastes—sweet, sour, salty, bitter, and umami—which are detected by taste buds.
The Chemistry of Heat
Spicy foods contain chemical irritants. Capsaicin is the primary compound responsible for the heat in chili peppers.
Other foods also contain compounds that elicit a similar sensation. Piperine gives black pepper its characteristic pungency. Gingerol is the active compound in ginger, producing its warm, pungent taste. The sharp, irritating quality of wasabi and mustard comes from allyl isothiocyanate.
Your Body’s Spice Detectors
The body detects these chemical irritants through specialized receptors, primarily the Transient Receptor Potential Vanilloid 1 (TRPV1) receptor. This receptor is present not only in the mouth but also on other mucous membranes and the skin. TRPV1 responds to a variety of stimuli, including high temperatures above 43 °C (109 °F), acidic conditions, and compounds like capsaicin.
When capsaicin binds to the TRPV1 receptor, it activates nerve signals. These signals are sent to the brain, which interprets them as a burning or painful sensation. The brain perceives spiciness as heat because the same receptors that detect chemical irritants also respond to actual high temperatures.
Measuring the Burn
The intensity of spiciness, particularly in chili peppers, is quantified using the Scoville Heat Unit (SHU) scale. American pharmacist Wilbur Scoville developed this scale in 1912. The original method, the Scoville organoleptic test, involved diluting pepper extract until a panel of tasters could no longer detect any heat; the SHU rating corresponded to the degree of dilution required.
For example, a bell pepper has 0 SHU because it contains no capsaicin, while a jalapeño typically ranges from 2,500 to 8,000 SHU. Habanero peppers are significantly hotter, often between 100,000 and 350,000 SHU. Some of the world’s hottest peppers, like the ghost pepper, can exceed 1,000,000 SHU. Modern methods use high-performance liquid chromatography to precisely measure capsaicinoid concentration, which is then converted to SHU.
Relief Strategies
Relief strategies often interact with capsaicin’s properties. Dairy products are effective because they contain casein, a protein that binds to capsaicin molecules and helps wash them away. The fat content in dairy also helps dissolve capsaicin, as capsaicin is fat-soluble.
Sugar and carbohydrates can also offer relief. Sugar works by bonding with capsaicin. Carbohydrates, such as bread or rice, can physically absorb and dilute the capsaicin in the mouth. Alcohol can dissolve capsaicin because capsaicin is alcohol-soluble. However, lower alcohol content in beverages like beer means they are less effective, and the water content can spread the irritant. Water is generally ineffective because capsaicin is not water-soluble, which can intensify the burning feeling.