Sinigrin

Sinigrin is a glucosinolate that belongs to the family of glucosides found in some plants of the Brassicaceae family such as Brussels sprouts, broccoli, and the seeds of black mustard (Brassica nigra) to name but a few. Whenever sinigrin-containing plant tissue is crushed or otherwise damaged, the enzyme myrosinase degrades sinigrin to a mustard oil (allyl isothiocyanate), which is responsible for the pungent taste of mustard and horseradish. Seeds of white mustard, Sinapis alba, will give a much less pungent mustard because this species contains a different glucosinolate, sinalbin.