The chemical, allyl isothiocyanate, that is released when you eat those things releases vapor that travel to your nasal cavity and cause that stinging sensation. It doesn’t, however, trigger your capsaicin receptors, so it doesn’t cause the sensation of spiciness that a pepper would.
Because the “spiciness” is actually two different sensations caused by two different chemicals. The spiciness in wasabi is caused by allyl isothiocyanate while the spiciness in peppers is caused by capsaicin.
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The chemical, allyl isothiocyanate, that is released when you eat those things releases vapor that travel to your nasal cavity and cause that stinging sensation. It doesn’t, however, trigger your capsaicin receptors, so it doesn’t cause the sensation of spiciness that a pepper would.
Because the “spiciness” is actually two different sensations caused by two different chemicals. The spiciness in wasabi is caused by allyl isothiocyanate while the spiciness in peppers is caused by capsaicin.