Mustard can be processed into several forms ranging from whole seed in spice blends to finely ground defatted and/or deheated powders. Food manufacturers process mustard in several different forms depending on what component of the seed is important to them. Mustard seed has many different fractions or components including glucosinolates, mucilage, oil and meal.
Glucosinolates give rise to the hot principle and pungent taste of mustard. An enzyme, active in the presence of water, hydrolyses glucosinolates to give rise to subsidiary compounds that actually impart mustard’s characteristic flavour. The compounds, isothiocyanates, are different depending on the type of mustard. Yellow mustard contains hydroxybenzyl isothiocyanate (derived from sinalbin), while oriental and brown contain allyl isothiocyanate (derived from sinigrin). The allyl form is much hotter than the hydroxybenzyl form and is responsible for the hot taste of Dijon style mustard.
Medical researchers have tested glucosinolates for benefits such as decreasing blood cholesterol and blood glucose levels as well as having antioxidant properties. In addition, researchers have identified insecticidal properties with activity against nematodes.
Mucilage is the outermost coating of yellow mustard seeds. In years characterized by repeated wetting and drying cycles during maturation, it can flake off and take on a white hue, a condition commonly referred to as rime in western Canada. Mucilage is a polysaccharide that gives yellow mustard its thickening, water binding and emulsifying properties that are important in the making of salad dressings, mayonnaise and prepared meats.
Mustard is considered a spice crop, however yellow mustard contains approximately 30 per cent oil, while brown and oriental mustard can approach 40 per cent. Mustard oil, regardless of type, is not considered fit for human consumption in North America because of the relatively high concentration of erucic acid, the fatty acid that was removed from canola in its transformation from industrial oil to cooking oil. However, many cultures in Asia use high erucic acid oil for cooking and subsequently they form much of our markets for oriental mustard. Mustard oil is also suitable for industrial applications like biodiesel and other lubricants.
Meal is the largest fraction of mustard seed and contains both glucosinolates and mucilage. Heating mustard meal destroys the enzyme myrosinase which is responsible for the conversion of glucosinolates to iosthiocyanates making mustard meal suitable for several applications including food ingredients.