What Makes Food Spicy?

(Last Updated On: September 14, 2018)

What Makes Food Spicy?

What makes food spicy? Hot sauce aficionados may think they have an easy answer to this, but the explanation actually goes beyond Scovilles. Hot sauces often proudly display their Scoville units prominently on packaging, and while that is one measure of heat, it’s not the only one. Multiple compounds create spice in food, and the flavors of a dish can differ pretty dramatically based on this.

What Makes Food Spicy?


Hot peppers have a quite a reputation to hold up. The most popular scale for heat is the Scoville scale, which is entirely based around capsaicin – the compound that gives hot peppers their spice. Growers of hot peppers compete to see who can develop the hottest possible fruits, with specific peppers gaining popularity and name recognition. Ghost peppers, Trinidad scorpions, and Carolina reapers for example, have all gained reputations through everything from hot sauces to painful YouTube challenges. Heat-fiends may find capsaicin to be their best friend. But other compounds contribute to spiciness as well.

Black Pepper

Black pepper is the only spice popular enough to stand next to salt. And while it may share a name with hot peppers, the compound that gives black pepper it’s heat is actually entirely different. It’s called piperine. It’s related to capsaicin, but not quite as potent. Other “table” peppers like white pepper or red pepper are from the same plant usually, and thus piperine-based as well. Piperine, being milder, is easier on sensitive palettes, and that probably contributes to pepper’s mainstream popularity.

Hot Mustard/Wasabi/Horseradish

Stepping even further away from peppers, there’s allyl isothiocyanate. That’s the compound that gives heat to wasabi and other Brassica vegetables like horseradish or mustard. This compound is said to stimulate the nasal passages with heat more than the mouth or tongue, where hot peppers are more direct to the mouth. Wasabi also wears off much more quickly – one punch of heat and then it’s gone. Hot mustard and horseradish work similarly, almost coming across more ‘pungent’ than ‘spicy’.


Cooked garlic is mild, but raw garlic and raw onions can be surprisingly intense. Allicin is responsible for that. It can vary pretty widely in concentration in different kinds of onions and garlic. But even the harshest garlic mellows out quickly on a hot pan, because allicin isn’t heat stable. That makes it somewhat tough to use allicin for it’s spiciness, and most uses of garlic involve cooking it. As far as spicy compounds go, it’s fairly limited in how it can be used.

If you think you’ve got spicy food on lock (or just want to know what to avoid), check out this quiz on hot and spicy foods. or check out out Sporcle’s food subcategory for even more quiz fun.