system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some spicy foods (like Jalapeño Peppers) cause a burning sensation on your tongue, and other spicy foods (like Wasabi) cause a burning sensation in your nose?

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gpt
Both flavors are caused by chemical irritants, but different chemical irritants. Chili peppers contain capsaicin, which stimulates heat receptors in mucous membranes, giving the sensation of burning without any actual heat. This compound is stored in the pepper itself and will sit on your tongue/in your mouth, causing irritation.

Wasabi, horseradish, and mustard contain allyl isothiocyanate. Breaking the cell walls of the plant generates a irritating gas that you inhale, which is why you feel it more in your nose/ This is also why it's important to use fresh wasabi/horseradish, while chili products can stay pungent for years.