About Wasabi
What real wasabi is, and why it’s so rare.
Twelve facts about real wasabi: how it grows, what sets it apart, and why so little of it reaches your plate.
Twelve facts
It’s a rhizome, and the whole plant is edible.
What gets grated is the rhizome, an underground stem. The leaves and flowers are edible too.
Real wasabi is Eutrema japonicum.
It was long classed as Wasabia japonica. It belongs to the Brassicaceae family, alongside horseradish, mustard, cabbage, broccoli and kale.
It’s Japanese in origin and well over a thousand years old.
The plant is native to Japan, the Russian Far East (including Sakhalin) and the Korean Peninsula. The oldest record of wasabi as food dates to the 8th century, and some accounts trace its use in Japan to 794 CE.
One rhizome takes roughly two years to grow.
Estimates range from about 18 months to 3 years, with around two years typical for a full-size rhizome of 4–6 inches. One grower reports cutting the time to 15 months with hydroponics.
It wants cool, dark and wet.
Wasabi grows best with air around 50–60°F, water at 45–55°F, and at least 75% shade during the day.
Clean, moving water is a big part of the recipe.
Wasabi is semi-aquatic. It needs cool water bathing the plants year-round but does badly in standing water. In Japan, the traditional stream-fed method is called sawa wasabi.
Most “wasabi” outside Japan isn’t wasabi.
The green paste served with most sushi is typically horseradish and mustard, colored with food dye or spinach powder. One industry report estimates a standard packet holds about 0.5% real wasabi at best.
Real and imitation differ in taste and texture.
Fresh wasabi is gritty, fresher, sweeter and more fragrant, with a natural green that varies by cultivar. Imitation tends to be a smooth, thick paste that is harsher and lingers longer.
The heat hits your nose, not your tongue.
The pungency comes from isothiocyanates, mainly allyl isothiocyanate, which forms when the plant’s cells are broken during grating. It stimulates the nose more than the tongue and activates a receptor called TRPA1, nicknamed the “wasabi receptor.”
The burn fades in minutes.
Freshly grated wasabi begins losing its punch after roughly 10–15 minutes, which is why it’s grated just before serving. Horseradish, by contrast, stays hot for hours.
Traditionally, it’s grated on sharkskin.
The classic tool is a piece of dried shark skin on a wooden paddle. Modern kitchens often use fine metal graters called oroshigane, and premium restaurants grate it to order.
A wasabi smoke alarm won an Ig Nobel Prize.
The 2011 Ig Nobel Prize in Chemistry went to Makoto Imai and colleagues for a fire alarm that releases wasabi vapor to wake people who can’t hear a conventional alarm.