The hot side of chiles.

The hot side of chiles

Capsaicinoids are the chemicals that impart the flaming bite to chiles and other hot peppers. Having almost no odor or flavor, they act directly on pain receptors in the mouth and throat. Anna Krajewska and John Powers at the University of Georgia in Athens asked 16 trained tasters to characterize very dilute solutions of the four most prevalent naturally occurring members of this family of stinging chemicals and one synthetic cousin, used as a reference gauge of the others' hotness.

Reporting in the May-June JOURNAL OF FOOD SCIENCe, the researchers find nordihydrocapsaicin (NDHC) and the synthetic vanillylamide of n-nonanoic acid (VNA) the mildest and "least irritating." They were also only about half as hot as capsaicin (C) an dihydrocapsaicin (DHC), the most pungent and prevalent two. NDHC's "mellow warming" develops immediately after swallowing, recedes rapidly and centers in the front of the mouth and palate. Overall, its character is "fruity, sweet and spicy." In contrast, the inflammatory response induced by homodihydrocapsaicin (HDHC) -- which is about two-thirds as hot as C and DHC -- does not develop immediately. Once it does, HDHC stings with a "very irritating" and "numbing burn" in the throat and back of the tongue and palate. Its pungency is also the most prolonged and difficult to rinse out.

The two hottest capsaicinoids deliver their bit everywhere from the mid-tongue and palate back down into the throat. How hot is that? A single drop of capsaicin diluted in 100,000 drops of water will produce a persistend burning of the tongue. Diluted in 1 million drops of water, it still produces a perceptible warmth. Like DHC's, its sharp sting develops rapidly and lasts longer than NDHC's.