I'm a wasabi addict -- I love walking on the edge between just enough wasabi and a little too much, and I love the endorphin rush when too much wasabi makes your sinuses explode. But I've always wondered what the exact mechanism is -- how does wasabi in your mouth cause the exploding sensation in your nasal cavities?
Recently I saw a chemical diagram of the characteristic molecule of wasabi on a T-Shirt (you've probably seen them, they have the chemical diagrams for caffeine, cocaine, chocolate, etc.). I asked the guy, and he told me that the molecule is a glucose ring with an attached sulfur salt. When the molecule reacts chemically with your saliva it produces a small amount of sulfuric acid vapor, which then can go up the nasal openings at the back of the palate.
Does anyone know enough chemistry to know whether this is a reasonable explanation?