Wasabi

• wasabiわさび

  Japanese

  Japanese distinguishes hon-wasabi (本わさび), the true plant, from seiyō-wasabi (西洋わさび), literally "western wasabi", which is horseradish. A tube labelled only "wasabi" has told you nothing about which it contains.

• namida涙

  Japanese — Sushi counters

  Trade slang meaning "tears", used when ordering. Not a name for the plant and not understood as one outside that setting.

• shankui山葵

  Mandarin

  The same characters Japanese uses for the plant. In everyday Chinese use the term is applied to horseradish-based pastes as readily as to the plant.

A brief, intense nasal heat followed by a genuine sweetness and a green, almost herbaceous finish. The heat rises rather than spreads and is gone in seconds, which is precisely the opposite behaviour to chilli. Freshly grated it is noticeably sweeter and less coarse than horseradish; the tube product has the burn and not the sweetness.

Sharp, clean and vegetal, closer to fresh brassica leaf than to anything hot, with a sweetness underneath that survives only in the fresh grated rhizome. The volatile burn arrives as sensation rather than as smell.

The fresh rhizome is pale green, deepening towards the crown, and grates to a soft green paste with visible texture. The uniform bright green of tube paste is added colouring; nothing about the plant produces it.

Grated fine on a sharkskin board it is a smooth, slightly foamy paste; on a metal grater it is coarse and watery and gives up its aroma faster.

• Allyl isothiocyanate — The immediate nasal burn, shared with horseradish and mustard, and the reason all three are interchangeable in sensation if not in flavour.
• 6-methylsulfinylhexyl isothiocyanate — A longer-chain isothiocyanate more characteristic of wasabi, contributing to the sweeter, rounder character of the fresh rhizome.
• Myrosinase — Not a flavour compound but the enzyme that makes the others. Held apart from the glucosinolates in the intact cell and released on grating.

Everything about using wasabi follows from one fact: the pungency is created by grating and destroyed by time and heat. Grate immediately before serving, grate only what will be eaten within a quarter of an hour, and never cook it — added to a hot sauce it contributes a faint cabbage note and nothing else. If it must go into something warm, it goes in off the heat at the very end. Do not stir it into soy sauce if you want to taste it, because the volatiles disperse into the liquid rather than into you. Fat is the exception worth knowing: mayonnaise, cream and butter hold the volatiles and release them slowly, which is why wasabi mayonnaise works far better than wasabi in a hot broth.

Japanese cooking almost exclusively: sashimi and nigiri, soba dipping sauce, chazuke, and as a seasoning for grilled fish and beef. Outside Japan it appears mostly as prepared paste in dressings, mayonnaise, crusts for salmon and beef, and in snack seasoning. It works with raw fish, salmon, tuna, beef, avocado, rice, soy and dairy, and the last of those is the useful one: cream, mayonnaise and butter carry its volatility and soften the attack without dulling it.

• grinding — The whole mechanism. An intact rhizome is almost odourless; grating ruptures the cells, myrosinase meets the glucosinolates, and the isothiocyanates are created within seconds. A finer grate ruptures more cells and produces more pungency, which is why the traditional sharkskin grater is not affectation.
• boiling — Destroys it. Heat denatures the enzyme and drives off the volatiles, so wasabi added to a hot dish contributes a faint cabbage note and nothing else. It is a finishing condiment and cannot be cooked.

Grate a little and smell it. Fresh rhizome produces a sharp nasal hit within seconds and a green sweetness behind it; old rhizome smells faintly of cabbage and produces nothing. For powder, mix a pinch with cold water and wait two minutes — if there is no burn, the tin has taken up moisture and there is no fixing it.

• A soft or shrivelled rhizome, or one that has gone woody and fibrous at the tail.
• A brown, dried-out cut face — trim it back rather than discarding the rhizome.
• Blue-green mould at the crown or the cut end, which does mean discarding it.
• Paste that has browned at the nozzle or separated in the tube.
• Powder that has caked into lumps, which means it has already reacted.

The clearest whole-versus-processed case in the dataset, and also the one where the processed form is most defensible. Fresh rhizome is a genuinely different and better ingredient, and it is expensive, perishable and pointless unless it is being tasted directly. For sashimi it is worth the money and the trouble. For a wasabi mayonnaise, a dressing or a crust on a piece of beef, the tube is doing a job the rhizome would do no better and at forty times the cost — the sweetness and the green note that justify the fresh product are lost in any of those anyway. Buy the rhizome for the plate and the tube for the kitchen, and do not feel cheated by the second.

• A firm rhizome with a taut, even green surface and no soft patches or shrivelling.
• Length and thickness: a stubby or tapering rhizome has been lifted young and will be milder.
• Fresh leaf stalks still attached, which is the clearest sign of when it was lifted.
• On a tube or tin, a stated hon-wasabi percentage. Its absence is not a scandal, but it does mean you are buying horseradish.
• Water-grown (sawa) stated explicitly where you are paying a premium.

No international standard exists. The Japanese trade grades whole rhizome on size, straightness and colour, and separates water-grown from field-grown, which is the distinction that matters most to flavour. None of it grades pungency, which is not measurable until the rhizome is grated and which varies along its length in any case.

Brassicaceae

A slow-growing perennial of shaded mountain streambeds, producing a rosette of long-stalked heart-shaped leaves above a green rhizome that lengthens by a few centimetres a year. It takes between eighteen months and three years to reach a usable size, which is most of the explanation for the price.

Japan, where the plant grows wild in mountain stream valleys and has been cultivated since at least the seventeenth century.

• JP (Shizuoka (Izu peninsula and Utogi)) — origin. The centre of water-grown cultivation, and where the terraced streambed method is documented from the Edo period.
• JP (Nagano (Azumino)) — major producer
• JP (Iwate) — notable producer
• TW — notable producer. Grown in the high mountains since the Japanese colonial period.
• NZ — notable producer. One of a small number of non-Asian producers, alongside growers in Oregon and southern England.

Lifted by hand at eighteen months to three years, when the rhizome has reached roughly fifteen centimetres. Leaves and petioles are cut through the growing period and sold separately.

1. Trimming — Leaves and rootlets removed and the crown cleaned. The rhizome is sold whole and unprocessed for the fresh trade, and everything below applies only to the processed products.Why: The fresh rhizome is the premium product and is not processed at all.
2. Drying and milling — Rhizome sliced, dried and ground to powder for the reconstituted product. Drying costs most of the volatile pungency, which is why powders rely on added horseradish and mustard to have any bite.Why: Shelf stability, at the cost of the aroma.
3. Compounding — Horseradish, mustard, colouring, sweetener and stabiliser blended into a paste. Where any Eutrema is present, Japanese labelling states its proportion.Why: To produce a shelf-stable product with the sensation of wasabi at a fraction of the cost.

No international grading standard. Japanese trade practice grades whole rhizome on length, thickness, straightness and evenness of colour, and water-grown commands a large premium over field-grown. Nothing in a grade describes pungency, which cannot be assessed until the rhizome is grated.

The wrong word for what happens here, and using it is why the subject is so badly reported. Horseradish-and-mustard paste sold as "wasabi" is a substitution made in the open: the ingredients are declared, the substitute has its own established name in Japanese, and in Japan the label distinguishes hon-wasabi from seiyō-wasabi. What is fair to say is that the word "wasabi" alone, on a tube or a menu outside Japan, carries no information about which plant is in it. SpiceHQ states no proportion, because it holds no survey of the market and every figure in circulation traces back to an assertion rather than a count.

Two systems, and they produce noticeably different products. Sawa wasabi is grown in terraced gravel beds fed by diverted mountain streams, takes two years or more, and gives the fine-textured rhizome sold whole at a high price. Oka wasabi is field-grown in soil under shade, is quicker and far cheaper, and gives a smaller, harsher rhizome mostly destined for processing. Water-grown is the one a sushi counter means.

Cold, shaded and constantly wet. The plant wants water between roughly 10 and 15 degrees Celsius moving continuously past the roots, and it fails in still water, in warmth and in direct sun. That combination exists in very few places, which is the constraint the whole economics of the crop rests on.

Documented in Japan from at least the tenth century as a wild-gathered plant, and cultivated deliberately from the early Edo period, when terraced streambed growing was established in the Shizuoka valleys. Its association with raw fish is later and practical: it belongs to the same period as the emergence of nigiri sushi as street food in Edo, where a pungent condiment served an obvious purpose alongside fish held at ambient temperature. The plant never entered the spice trade, because it cannot be dried without losing what it is and does not survive shipping.

Almost no historical trade to speak of, which makes wasabi unusual among the entries in this dataset. Every other pungent seasoning here travelled because it dries; wasabi does not, so it stayed where it grew until refrigerated air freight, and the global market that exists today is overwhelmingly a market in horseradish-based substitutes rather than in the plant.

Recorded in Japanese tradition as a digestive and as a preservative accompaniment to raw fish. Held here as tradition and as context for the culinary practice, and not as a health claim.