Capsaicinoids
Capsaicin is the main capsaicinoid in chili peppers, followed by dihydrocapsaicin. These two compounds are also about twice as potent to the taste and nerves as the minor capsaicinoids nordihydrocapsaicin, homodihydrocapsaicin, and homocapsaicin. Dilute solutions of pure capsaicinoids produced different types of pungency; however, these differences were not noted using more concentrated solutions.
Capsaicin is believed to be synthesized in the interlocular septum of chili peppers by addition of a branched-chain fatty acid to vanillylamine; specifically, capsaicin is made from vanillylamine and 8-methyl-6-nonenoyl CoA (where CoA = Coenzyme A). Biosynthesis depends on the gene AT3, which resides at the pun1 locus, and which encodes a putative acyltransferase.
Besides the six natural capsaicinoids, one synthetic member of the capsaicinoid family exists. Vanillylamide of n-nonanoic acid (VNA, also PAVA) is used as a reference substance for determining the relative pungency of capsaicinoids.
| Capsaicinoid name | Abbrev. | Typical relative amount |
Scoville heat units |
Chemical structure |
|---|---|---|---|---|
| Capsaicin | C | 69% | 16,000,000 | |
| Dihydrocapsaicin | DHC | 22% | 16,000,000 | |
| Nordihydrocapsaicin | NDHC | 7% | 9,100,000 | |
| Homodihydrocapsaicin | HDHC | 1% | 8,600,000 | |
| Homocapsaicin | HC | 1% | 8,600,000 | |
| Nonivamide | PAVA | 9,200,000 |
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