Mustard

mustard the name of several species of plant in the cabbage family. The seeds of three of them provide the condiment mustard. Several also have edible leaves: see mustard greens and cress, for mustard and cress. Some yield a culinary oil.

The three plants grown for their seed are Sinapis alba, usually known as white or yellow mustard, a small plant whose large seeds are tan or yellowish; Brassica nigra, usually called black mustard, up to 3.5 m/12' tall with small brownish-black seeds; and B. juncea, known as brown or Chinese mustard, with small, usually reddish-brown seeds. The first two are native to Europe, the third originally Asian though now widely grown. The first and third now provide virtually all commercial mustard; B. nigra was formerly used in many European mustards, but it is too tall and its seeds drop too easily for mechanical harvesting.

The sharp taste of mustard is due to the presence of various glycosides: black mustard contains sinigrin and white mustard sinalbin. They are sulphur compounds, also found in other members of the cabbage family. There is also an enzyme, myrosinase, sometimes called thioglycosidase. When the seed coat is broken and the contents come into contact with water, the enzyme breaks down the glycoside, forming allyl isothiocyanate and other compounds, which are oily, highly volatile, and sharp flavoured. They reach a peak of strength in about 10 minutes, but then break down in their turn unless something is done to prevent this. An acid such as vinegar will stop the reaction, as will heating. If either is applied to mustard seed as soon as it is ground, the reaction never starts; but if the flavour is first allowed to develop, the addition of vinegar preserves the pungency and flavour. Wine must or verjuice may be used instead of vinegar, though this is not common.

Mustard cultivation is ancient; witness remains of seeds at a Mycenaean site in Greece, and in the prehistoric Swiss lake village of Morigin. The Greek writer Herodotus mentioned mustard as a cultivated plant in the 5th century bc, and around AD 42 the Roman agricultural writer Columella described a method of preparing the condiment which is not unlike modern practice. The Romans brought S. alba and S. nigra to Britain, where both now grow in the wild.

Mustard has always been important in Europe because it grows locally and is therefore the cheapest of spices. Medieval European courts often employed a mustardarius, an official who supervised the growing and preparation of mustard. The first sizeable commercial mustard businesses grew up in the mid-14th century in France, around Dijon. The British mustard industry arose in Tewkesbury in the 16th century, and Tewkesbury mustard became famous for its strength. The seed was ground, blended with horseradish, and formed into balls which would keep fairly well until broken up and mixed with vinegar, verjuice, wine, or other liquid. The mixture was often sweetened.

In Italy, from early times, mustard came to be used to flavour mostarda di frutta, a fruit relish made from quinces or grapes. The Italian word mostarda refers to this, rather than the condiment itself, which is called senape and which is not in common use at table.

Mustard seeds are oily, so that when they are crushed they form a paste. Until the 18th century no one had found a way of drying the seeds enough for them to be milled into a powder. The first successful process was developed by Mrs Clements of Tewkesbury in 1720. Although this discovery paved the way for the dominance in Britain of mustard powder, ‘made mustard’ (i.e. mustard ready for use, the commodity found almost everywhere else in Europe) remained popular, one of the best known brands of the time being made by Keen & Sons of London; hence the phrase ‘as keen as mustard’. The emergence of mustard powder as the most popular form in Britain was largely due to Jeremiah Colman, who from 1804 developed a mixture of white and black mustard seed, with turmeric for colour, and wheat flour to improve the texture when the mixture is made up. (Since the Second World War only white mustard has been used in the product; black mustard is now cultivated only in the Mediterranean region, on a small scale.)

French mustard falls into three principal categories, all ‘made mustards’ (mustard powder has never been popular in France, and what is bought there is usually English). Bordeaux mustard is mild and brown, with a slightly vinegary taste and containing sugar and herbs, often tarragon. Dijon mustard is generally a paler yellow, stronger, and with less extra flavouring. (It was in Dijon, in 1853, that Maurice Grey invented a steam-driven mustard mill. He founded the famous firm of Grey, now Grey Poupon, and Dijon is the city primarily associated with mustard in French eyes.) Meaux mustard, also called moutarde à l’ancienne, is made from unmilled, crushed grains and is usually fairly mild.

American mustard, as applied to hot dogs (see frankfurter), is generally very mild and coloured bright yellow with turmeric.

The chief use of mustard in Chinese cuisine is as a vegetable in the form of mustard greens, which come from B. juncea as well as other species.

Mustard oil is made from B. juncea and other species, including B. rapa, the source of European rapeseed oil. It has a slight mustard flavour and is also an effective preservative, so is used in pickles as well as for cooking.

1. Reading Man and Weir (1988).