I checked the ingredient list on my powder: horseradish, mustard, corn starch and yellow #5. This is evidently a common substitute for real wasabi.
On the paste tube: no listing. it must have been on the box which is long gone. I'll try to remember to look at a box next time I'm at the grocer. I'm under the impression it is the real stuff thou.
Came across interesting things while looking into exactly what wasabi is....
** 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. The 2011 Ig Nobel Prize in Chemistry was awarded to the researchers for determining the ideal density of airborne wasabi to wake people in event of an emergency.**
**Its hotness is more akin to that of a hot mustard than that of the capsaicin in a chili pepper, producing vapours that stimulate the nasal passages more than the tongue.**
**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.**
Meddle not in the affairs of dragons for you are crunchy and taste good with ketchup.