Horseradish (Armoracia rusticana, syn. Cochlearia armoracia) is a perennial plant of the Brassicaceae family, which includes mustard and cabbages. The plant is probably native to southeastern Europe and western Asia, but is popular around the world today. It grows up to 1.5 metres (five feet) tall and is mainly cultivated for its large white, tapering root, although the leaves are also edible.
Its root is used as a vegetable or condiment, and has at times been used as the bitter herbs in the Passover meal in some Jewish communities. Horseradish, sometimes blended with cream, is often served with roast or boiled beef or sausages, as well as smoked fish. Horseradish is also used in some prepared mustards. Also, much of what is styled wasabi is actually common horseradish dyed green.
The horseradish root itself has hardly any aroma. When cut or grated, however, enzymes from the damaged plant cells break down sinigrin (a glucosilinate) to produce allylisothiocyanate (mustard oil), which irritates the sinuses and eyes. Once grated, use horseradish immediately or mix it in vinegar, as the root darkens and loses its pungency and becomes unpleasantly bitter when exposed to air and heat.
Over two thirds of the world's horseradish is said to be grown in a small region around Collinsville, Illinois in the US, the self-styled "Horseradish Capital of the World", whence it is even exported overseas as a gourmet version of the product to places more renowned for consumption of the root.
It has been speculated that the word is a partial translation of its German name Meerrettich. The element Meer (meaning 'ocean, sea') is pronounced like the English word mare, which might have been reinterpreted as horseradish. On the other hand, many English plant names have "horse" as an element denoting strong or coarse, so the etymology of the English word (which is attested in print from at least 1597) is uncertain.
Horseradish contains potassium, calcium, magnesium and phosporus, as well as volatile oils, such as mustard oil, which is antibiotic. Fresh, the plant contains 177,9 mg/100 g of vitamin C. The enzyme horseradish peroxidase, found in the plant, is used extensively in molecular biology in antibody amplification and detection, among other things.
Horseradish was cultivated in antiquity. Cato discusses the plant in his treatises on agriculture, and a mural in Pompeii showing the plant has survived until today. It is probably the plant mentioned by Pliny under the name of Amoracia, and recommended by him for its medicinal qualities, and possibly the Wild Radish, or raphanos agrios of the Greeks.
Both root and leaves were universally used as a medicine during the Middle Ages, and as a condiment in Denmark and Germany. William Turner mentions horseradish as Red Cole in his "Herbal" (1551-1568), but not as a condiment. In "The Herball, or Generall Historie of Plantes" (1597), John Gerard describes it under the name of raphanus rusticanus, stating that it occurs wild in several parts of England. After referring to its medicinal uses, he says: the Horse Radish stamped with a little vinegar put thereto, is commonly used among the Germans for sauce to eate fish with and such like meates as we do mustarde. Before pepper and chiles became widely available, horseradish and mustard were the only sharp spices known in Europe.