Dijon Mustard

The science of mustard relies on a chemical defense mechanism of the plant. Brown mustard seeds (Brassica juncea) are not pungent until crushed: grinding brings sinigrin and the myrosinase enzyme into contact, creating allyl isothiocyanate, the volatile gas that shoots up the nose. Bound with verjus or vinegar, this reaction is locked in. In cooking, beyond its heat, the mucilage contained in the seed acts as an overpowered surfactant emulsifier, capable of forcing the stable binding of oil and water in a vinaigrette.