For a while, I was under the impression that all spiciness, or burning sensation in food flavoring, would come from capsaicin, the compound that causes it in chili peppers. Then I realized that Sichuan peppers are a quite different kind of heat. Wasabi (horseradish) is different yet again.
How many hot-flavored compounds are there? At least five!
Kalsec: "The Elements of Heat"
@clacke
Plus all the stuff going on with alliums!
https://en.wikipedia.org/wiki/Alliinase
Alliinase