The chemical in wasabi that provides for its initial pungency is the volatile allyl isothiocyanate, which is produced by hydrolysis of natural thioglucosides (conjugates of the sugar glucose, and sulfur-containing organic compounds); the hydrolysis reaction is catalyzed by myrosinase and occurs when the enzyme is released on cell rupture caused by maceration — e.g., grating — of the plant.[11][12][13] The same compound is responsible for the pungency of horseradish and mustard.
The unique flavor of wasabi is a result of complex chemical mixtures from the broken cells of the plant, including those resulting from the hydrolysis of thioglucosides into glucose and methylthioalkyl isothiocyanates:[14][15][16]
6-methylthiohexyl isothiocyanate
7-methylthioheptyl isothiocyanate
8-methylthiooctyl isothiocyanate
Research has shown that such isothiocyanates inhibit microbe growth, perhaps with implications for preserving food against spoilage and suppressing oral bacterial growth.[17]
Because the burning sensations of wasabi are not oil-based, they are short-lived compared to the effects of chili peppers, and are washed away with more food or liquid. The sensation is felt primarily in the nasal passage and can be quite painful depending on the amount consumed. Inhaling or sniffing wasabi vapor has an effect like smelling salts, a property exploited by researchers attempting to create a smoke alarm for the deaf. One deaf subject participating in a test of the prototype awoke within 10 seconds of wasabi vapor sprayed into his sleeping chamber.[18] The 2011 Ig Nobel Prize in Chemistry was awarded to the researchers for determining the ideal density of airborne wasabi to wake people in the event of an emergency.