What do you think of this fact?
A little green blob, a lot of heat, tears in your eyes: that’s wasabi as you know it from sushi. The bad news: what’s on your plate usually isn’t wasabi at all.
The great green impostor
Real wasabi is a plant (Eutrema japonicum, formerly Wasabia japonica) whose rhizome gets grated fresh. Outside Japan, though, you almost always get something else: a mix of horseradish, mustard, starch and green food coloring or spinach powder. According to Wikipedia, most sushi restaurants outside Japan use this powder, even good ones. According to Bustle, many tubes labeled “wasabi” contain only a tiny share of the real plant, often under one percent.
The heat isn’t completely fake, though. Horseradish, mustard and wasabi are related and produce the same spicy compound: allyl isothiocyanate. It only forms when the plant cells break open during grating. That’s why the imitation feels so similar.
Why the original is so rare
Wasabi is a true diva. The plant can’t handle direct sunlight and needs high humidity and temperatures between about 8 and 20 degrees Celsius. Traditionally it grows along cool mountain streams in Japan. Horseradish, on the other hand, grows faster, gets bigger and is much cheaper.
On top of that, real wasabi is a matter of minutes. Freshly grated, it keeps its full flavor for only about 15 minutes, according to HuffPost. Good restaurants therefore grate it right before serving. Premade paste from a tube can’t compete.
Wasabi was traditionally grated on rough sharkskin. Today, metal graters are the norm.
What does the real thing taste like?
According to HuffPost, real wasabi is smoother, cleaner and more “plant-like”. The heat hits briefly and then fades, instead of lingering like horseradish.
So your sushi has been working with a stunt double this whole time, and hardly anyone noticed.