Plants are capable of synthesizing two kinds of oils: fixed oils and essential oils. Fixed oils consist of esters of
glycerol and fatty acids (triglycerides or triacylglycerols), while essential oils are mixtures of volatile, organic
compounds originating from a single botanical source, and contribute to the flavor and fragrance of a plant.
Three commercial mustard species are commonly cultivated today. They are yellow or white mustard
(Sinapis alba L.), black mustard (Brassica nigra), and oriental mustard (Brassica juncea).
A range of essential oil components have been accepted by the European Commission for their intended use
as flavorings in food products. The U.S. Food and Drug Administration (FDA) classifies these substances as
generally recognized as safe (GRAS) that include, amongst others, clove, oregano, thyme, nutmeg, basil,
mustard, and cinnamon.
Essential oil of Brassica juncea mainly contains allyl isothiocyanate. The oil is not present in the in the seed
or powdered seed, but in the form of glycosides, so preparations made from these by mechanical means (i.e.
pressing) do not contain allyl isothiocyanate. The essential oil is only formed after fermentation, then
distillation.
When the mustard comes into contact with water, this hydrolyses sinigrin, a glycoside contained within the
seeds’ cells under the influence of myrosinase, an enzyme which is also present.Sinigrin is broken down
enzymatically by myrosinase, mainly into allylisothiocyanates (AITC) which is the main bioactive, responsible
for pharmacological effects. They have also been used as nutritional supplements for their preventive and
medicinal benefits on various diseases.White mustard seeds do not produce any allyl isothiocyanate under
these conditions The fixed oil from the seeds is also known as mustard oil.