Wasabi, Wasabi Paste, What is Wasabi

Family: Brassicaceae (Cruciferae; mustard family)
Scientific Name: Wasabia japonica (Miq.) Matsum. (Eutrema wasabi Maxim.)

• The Japanese name wasabi means “mountain hollyhock.” The English name wasabi was simply adopted from the Japanese, and the Japanese name also served as the root for the genus name Wasabia.
• Pronunciation: In Japan, WAH-sah-bee is correct, but some American dictionaries permit the accent on the second syllable.
• Wasabi is also known as Japanese horseradish. In parallel, horseradish is sometimes known as Western wasabi in Japan.
• In Japan, wasabi is known as seiyo. When conventional horseradish was first introduced, it became known as seiyo wasabi because the pungency was reminiscent of wasabi. Products manufactured from Western horseradish, not genuine wasabi, are sometimes exported as “wasabi,” which is misleading.
• The Japanese nickname of wasabi, namida, means tears, reflecting the strong pungent nature of the herb.
• Japonica in the scientific name W. japonica is Latin for Japanese.

Wasabi is a semi-aquatic perennial herb. Its native range is limited to regions of the Russian island of Sakhalin, north of Hokkaido, and to the major Japanese islands of Honshu, Shikoku, and Kyushu. The species grows wild in wet, cool mountain river valleys along stream beds and on river sand bars. A related, similar but smaller species, W. tenuis (Miq.) Matsum. (Eutrema tenue (Miq.) Makino), grows wild in Japan. Wasabi is typically not taller than 50 cm (20 in.). The leaves and leaf stalks are quite brittle and break easily. As the older leaves fall off, prominent scars are produced on the rhizome (underground or underwater stem, commonly called a “root”), giving a characteristic appearance. The rhizomes can be 2 to 5 cm (3/4–2 in.) thick and grow to a length of 5 to 40 cm (2–16 in.). Genuine “roots” that come off the rhizome are generally not sold commercially but are harvested where the plants are grown and used as a condiment. Wasabi can be cultivated on land and in water, but the latter is considered to produce a much higher quality product. Several cultivars are grown in Japan. The crop has been raised in Japan for more than a thousand years in cool streams or artificial water beds, much like watercress. The conditions for growing wasabi differ dramatically from the requirements of most crops and are quite demanding. Wasabi seeds and rhizomes that can be used to establish plants can be obtained from several commercial firms, but few people can provide the environment necessary for the plants to grow well. Requirements include considerable shade and cold welloxygenated water. Commercial cultivation occurs outside of Japan in Taiwan, North Korea, New Zealand, the Pacific Northwest of the United States and southwestern British Columbia. Fresh wasabi fetches approximately $220/kg in Japan ($100 a pound) and approximately $100 kg ($45 a pound) in North America.

In Japan, wasabi has been called “the king of the edible wild plants.” It is one of the three most important condiments in Japan (the others are grated horseradish and mustard) and is a staple of the country’s cuisine. Wasabi is primarily a Japanese condiment, mostly used to flavor sashimi (raw fish dishes), sushi fish dishes (sushi is cooked, seasoned rice, along with other ingredients), and soba (noodles). As sushi becomes more popular in Western countries, wasabi’s popularity is increasing. In Japanese restaurants, wasabi is typically served ground and placed in the corner of the plate in a tiny cone. In addition to traditional Japanese dishes, wasabi can be used as a condiment for grilled and roasted meats and vegetables and can be added to salad dressings, marinades, and dips. A variety of wasabi food products are marketed. Wasabi wines and liqueurs are sold in some Japanese specialty stores as novelties.

In Japan, wasabi is often used fresh, but in other countries, it is generally available dried, as a pale green powder, or in the form of a green paste with a very strong smell and taste. Wasabi has a distinct flavor that many, including the Japanese, consider superior to common horseradish. The same chemical that produces the pungency of horseradish, sinigrin, is responsible for the pungency of wasabi.

Wasabi is such an expensive condiment that the genuine article is rarely available. True wasabi is almost never offered in restaurants outside of Japan, and even in that country it has been found that only about 5% of restaurants provide the real thing. Indeed, powdered horseradish is used to adulterate wasabi. Such fraudulent substitution is inevitable because of the limited supply and great cost. Generally, the dab of pale-green paste served with sushi is imitation wasabi, usually a combination of horseradish, mustard, cornstarch, and artificial food coloring. An easy way to tell if genuine wasabi is being served is based on the fact that the isothiocyanate, which produces the sensation of heat, dissipates rapidly, and a fresh lump on the plate will lose most of its heat within 15 minutes. In a high-end restaurant that serves genuine wasabi, a waiter may be expected to come to the table occasionally to freshen up the condiment. Only enough material that can be consumed within approximately 15 minutes should be grated.

Wasabi powder is sold in shops specializing in Oriental foods, but the fresh rhizome is superior, although the flavor deteriorates rapidly after cutting. Occasionally, fresh wasabi is available but is quite expensive. Fresh, unshriveled rhizomes should be chosen, and these can be stored in damp towels in the refrigerator for up to 30 days. They may be rinsed in cold water every few days, and spoiled areas trimmed away when necessary. To use, first cut the rhizome just below the leaf bases, trim away bumps or rough areas, scrub with a stiff brush, peel with a knife, and grate. Wasabi is prepared by grating the fresh rhizome against a rough surface in much the same way that horseradish is prepared. Some Japanese sushi chefs will only use a sharkskin grater, which produces ground wasabi with a smooth, soft, and aromatic finish. (After use, a sharkskin grater should be rinsed under cold running water and left to air dry.) The rhizome is best grated with a circular motion. Holding the rhizome at a 90° angle to the grater is thought to produce an ideal size of particle and to minimize the root surface that is exposed to the air (if ground too finely, the flavor dissipates too quickly). Although a sharkskin grater is ideal, a ceramic grater with fine nubs is considered a good alternative. A stainless steel grater may also be used, using a side where the spikes are small. The grated wasabi is piled into a ball and allowed to stand at room temperature for 5 to 10 minutes to allow flavor and heat to develop. (The flavor will dissipate notably after approximately 15 minutes and is of limited desirability after approximately 4 hours.)

Wasabi powder normally contains ground yellow mustard to improve the pungency. To reconstitute wasabi powder, combine one part powder and three-fourth part water and use soon. The pungent taste does not develop until wasabi powder has been combined with water for several minutes. Dry wasabi powder tastes bitter. “Wasabi paste” in tubes is popular in Japan and typically actually contains some genuine wasabi, but mostly horseradish.

In Japan, wasabi leaves (especially the leaf stalks) are sometimes pickled fresh in sake brine or soy sauce, and dried leaves are used to flavor foods such as salad dressing, soups, cheese, and crackers. The leaves may become available in regions of the world that take up wasabi cultivation. Where they can be obtained, the same guidelines used for selecting salad greens can be used: choose those that look fresh, with no sogginess or wilting and with a uniform color. Wasabi leaves can be stored in a refrigerator but should be used as soon as possible.

There have been a few, isolated reports in the United States of serious adverse reactions to wasabi, involving paleness, confusion, profuse sweating, and collapse after eating a large serving; these reports suggested the response may be serious for those with weakened blood vessels in the heart or brain. However, it is unclear that genuine wasabi was involved, and the use of this condiment is not considered to be a threat to the health of most people.

Culinary Vocabulary
• An “Angry Red Planet” is a Bloody Mary cocktail with wasabi added.
• Consumers should not be misled by the Japanese words seiyo-wasabi (“western horseradish”), kona wasabi (“horseradish powder”), and wasabi daikon (“radish wasabi”), which are preparations made from common horseradish, not genuine wasabi.

• Medicinal values of chemicals extracted from wasabi were first documented in a tenth century Japanese medical encyclopedia. Natural chemicals (isothiocyanates) in wasabi may kill microbes responsible for food poisoning, a factor that might have led to the widespread use of the condiment with raw fish dishes in Japan.
• The isothiocyanates in wasabi may also have other medicinal properties. Research has suggested they may help treat or prevent blood clotting, asthma, and tooth decay. Isothiocyanates are also present in common horseradish, which can be expected to have the same effects.
• Roy Carver is the entrepreneur who first brought wasabi commercial cultivation and production to the United States. In 1991, Carver and a team of engineers and scientists set out to recreate in Florence, Oregon, the growing conditions demanded by wasabi. The Japanese producers refused to share critical crop information with Carver, but he nevertheless was able to acquire the necessary expertise. Carver’s team created a sophisticated irrigation system that pumps 114,000 L (3000 gallons) of water a minute through beds of round river rock in shaded greenhouses in which the wasabi plants now grow. The farm established in Oregon appears to be the largest of its type in the world.
• One of the reasons that has been advanced for the evolution of sex in living things is that it provides a mechanism for escaping diseases. In nature, it is very difficult to become free of a disease that has become established in the body of a plant or animal, but reproductive cells often are not infected, and when a disease-free sperm unites with a similarly uninfected egg, the new organism starts off healthy. Wasabi is easily grown from cuttings but is known to rapidly accumulate diseases when propagated vegetatively, and the diseases cannot be eliminated from the cuttings. Several viruses in particular have proven difficult to control. In Japan, crops established from cuttings are rotated with crops established from disease-free seed.
• Many nerve cells (neurons) in the human body are specialized to react only to certain chemicals, producing unique sensations, such as pungency and burning. For example, the distinctive taste stimulations produced by wasabi and chili pepper are sensed by different populations of neurons. Curiously, tetrahydrocannabinol, the psychoactive component of marijuana, activates both the wasabi and chili pepper neurons.
• Wasabi is the basis of an experimental smoke alarm for the deaf. Smoke triggers the device to spray wasabi vapor, and when placed near a sleeping subject the acrid sensation in the nasal passages has proven capable of quickly waking up people.
• In early March 2007, it was reported that a spill of wasabi had occurred on the International Space Station from a tube of the condiment being used by astronaut Sunita Williams. Space station crew members had been given special packs of their favorite foods to help endure their months in space. Unfortunately, under the weightless conditions of space, cleanup of spilled food is challenging, and it took a week to remove the wasabi.

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