Black Mustard (Brassica nigra [L.] Koch)

 

Black Mustard seeds

Used plant part

Seed grains. These are globular, dark brown and about one mm in diameter. The brown mustard species' seeds (see below) are larger (up to 2 mm) and somewhat less dark.

Plant family

Brassicaceae (cabbage family).

Sensoric quality

The dried seed do not have any fragrance, but exhibit a pungent taste after some time of chewing. Roasted seeds (more grey in colour) have a rich, nutty odour.

Main constituents

Black mustard contains about 1% sinigrin (allylglucosinolate), a thioglycoside-like compound (a so-called glucosinolate) of ally isothiocyanate with glucose. By action of the enzyme myrosinase, allyl isothiocyanate, a pungent, lachrymatory and volatile compound, is liberated (0.7% of the dried seed). Besides allyl isothiocyanat, in Romanian Brown Mustard another related compound is found, namely crotylisothiocyanat (2-butenylisothiocyanat).

Isothiocyanates are also the main ingredients of white mustard, horseradish, wasabi and cress, all of which belong to the same plant family. The more distantly related capers similarly owe their pungency to an isothiocyanate.
Note that isothiocyanates are highly toxic and can be used as chemical weapons, which is their biological function in the discussed plants anyway. To protect the plant organism from the isothiocyanates, they are glycosidically bound as glucosinolates (formerly called thioglycosides) and get liberated only if cells are damaged (which is supposed to have been caused by an eating animal).

Like all seeds, mustard seeds contain also significant amounts of fat oil (30%), which is used extensively for cooking in India (beware: the term mustard oil is both used for this fat oil and the pure isothiocyanates). Besides glycerides of linoleic and linolenic acid, mustard oil contains glycerides of erucic acid, which is considered harmful to human health; furthermore, traces of free isothiocyanates are always found in mustard oil. Therefore, in spice of its high fraction of unsaturated fatty acids (iodine index is 105), mustard oil cannot be recommended without qualification for cooking purposes (see also below).

Origin

Black mustard is probably endemic in the Southern Mediterranean region, but has been cultivated since thousands of years; therefore, numerous cultivars are found. None of them, however, reaches a size sufficient to host birds (not even kolibris); therefore, it is probable that the Biblical parable of the mustard grain referred to another plant (see also pomegranate).

Botanically different, though of equal use in the kitchen, are the Sarepta mustard or Romanian Brown Mustard (Br. juncea) from Eastern Europe and the Indian Brown Mustard (Br. integrifolia or Br. juncea, a fertile hybride from Br. nigra and Br. campestris) from India and the Middle East. Of all three species, the latter is probably most commonly sold in the West.

Although the pungency of black mustard is slightly stronger than that of brown mustard, black mustard is hardly planted in Europe anymore, and brown mustard is the dominating quality on the European market. The reason is that brown mustard, unlike black mustard, can be harvested by machines which make production much cheaper in countries where working force is expensive.

Etymology

The German Senf is a loan from Latin sinapi, as well as the Old English senep (preparation of mustard paste was introduced to central and Northern Europe by the Romans). The ultimate origin of this word is probably Egypt.

Mustard (and similar words in Roman languages, and the German Mostrich for mustard paste) is derived from Latin (vinum) mustum, "must". Although mustard paste is today predominantly prepared with vinegar and wine, the Romans (who made mustard seeds popular in Central and Western Europe) used must (young wine).

Lastly, the genus name Brassica is Latin for "cabbage", which belongs to the same genus.
 

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Black Mustard (flowering plant)

The world's harvest of black and brown mustard seeds is only to a small part used for the production of mustard paste, since the pungency of black mustard paste is not as stable as the pungency of white mustard, but diminishes after some time. The reason is that its pungent principle (allyl isothiocyanate) is volatile and hydrolyses slowly (i.e., gets destroyed by water). Therefore, and because the extremely strong pungency is not appreciated by Western consuments at all, white mustard is usually preferred for this purpose; some very pungent mustard specialities, however, use a mixture of both black and white mustard seeds or even black mustard seeds alone. To stabilize the pungency, these pungent mustards usually contain acidic components. See white mustard for more information on mustard pastes. See also sichuan pepper for a comparative review on pungent spices.

Black mustard is more important as a spice and oil plant, especially in India. Mustard oil, sometimes available in the West, is popular all over Northern India and especially indispensable for the true taste of Bengali cuisine, but since it contains toxic isothiocyanates, it must be strongly heated (until some smoke evolves) immediately before frying any food in it; otherwise, severe health damage is risked. Never use it for salads! Owing to paternistic laws, in most Western countries mustard oil is not a legal food additive and its sale is prohibited. Still, it can sometimes be found in ethnic food shops; for legal reasons it is then usually marked "for external use only". You needn't take this remark serious if you know about the heating procedure. See sesame for a general discussion on plant oils.

Black (or brown) mustard seeds are also much used as a spice directly. Their pungency is completely destroyed by cooking, and therefore the ground seeds should be added as late as possible. Indians fry or roast the seeds before usage until they become grey, which totally changes their character: They get an interesting nutty taste, which cannot be compared to any other spice and which is especially loved by South Indians.

Black mustard seeds are also a component in the Bengali spice mixture panch phoron (see nigella) and the South Indian composition sambaar podi (see cumin). In Southern India, perfumed butter (tadka, see ajwain) is commonly flavoured with black