Abstract: Yellow or oriental mustard seed can be fractionated to produce allyl isothiocyanate and p-hydroxybenzyl isothiocyanate, along with prepared mustard products, mustard protein and dietary fiber. Processes for the production of these various fractions from mustard seed stock are disclosed. The seed stock is comminuted with water to yield an activated slurry in which the enzyme myrosinase hydrolyses and deteriorates glycosinolates in the seed stock to isothiocyanates. Remaining slurry can then be sterilized and further conventionally processed to yield improved finished mustard products.