Most wasabi served outside Japan is actually horseradish
True wasabi is scarce, so the green paste beside sushi abroad is usually made from horseradish instead. Japanese botanists even call horseradish Western wasabi. Both belong to the cabbage family, and both keep their fire locked away until the root is crushed and a chemical defence springs into action.
An intact horseradish root barely smells. Cutting or grating it releases an enzyme, myrosinase, which acts on glucosinolates such as sinigrin to form allyl isothiocyanate, the mustard oil that stings eyes and sinuses. For the plant it is a weapon against grazing animals. Exposure to air or heat soon dulls the bite, darkens the colour and turns the flavour bitter, which is why prepared horseradish keeps only about three months in the fridge.
Armoracia rusticana probably originated in southeastern Europe and western Asia. It can reach 1.5 m tall, with glossy leaves up to a metre long that resemble docks, and it spreads so readily through underground shoots that unmanaged patches turn invasive. Growers dig the root after autumn frost kills the leaves and replant offshoots for the next crop. Europe produces around 30,000 tonnes a year, with Hungary the largest single producer at 12,000, while in the United States the heaviest concentration lies around Collinsville, Illinois.
People have grown it since antiquity: Cato wrote about it, and a mural at Ostia Antica depicts it. In 1597 John Gerard noted that Germans pounded it with vinegar as a sauce for fish, much as the English used mustard. English speakers were saying horseradish by the 1590s, horse once meaning coarse or strong. A popular story that it comes from a garbled German word lacks historical evidence. George Washington and Thomas Jefferson both mention it in garden records.
It carries religious weight too. Many Ashkenazi Jews use grated horseradish as the bitter herb at the Passover Seder, and chrain, white with vinegar or red with beetroot, is the classic partner for gefilte fish, attested in writing from the 12th century. In parts of Christian Europe it is eaten at Easter as a reminder of bitterness, and Polish cooks make horseradish soup on Easter Day.
Source: Horseradish
