A beloved dollop of colour which packs a punch and adds a certain something to your sushi lunch, wasabi is a mainstay of Asian cuisine. It may be a somewhat challenging flavour but combined with a little pickled ginger and soy sauce? Delicious. However, you’ve probably never actually eaten real wasabi.
Around 90 per cent of wasabi served in restaurants is actually horseradish which has been dyed green. Admittedly, this sounds like the catering equivalent of a tinfoil-hat-sponsored conspiracy theory. But it’s completely true.
Furthermore, it’s not like they are all that similar in terms of substance. White in the soil yet green above ground, horseradish is a root vegetable. Wasabi, on the other hand, is a rhizome. In other words, it is a continuously-growing underground stem that expands horizontally. Its stalks and roots grow vertically from the stem - which is the part of the plant we eat.
While in horseradish, we eat the root, in wasabi, we eat the stem. In essence, not only are they completely different plants - we also eat completely different parts of them. So why has the evil, many-tentacled restaurant industry been fooling us with bogus wasabi?
Like getting pandas to mate, it’s incredibly difficult to grow wasabi plants. They’re very sensitive to both sunlight and warm temperatures (wasabi plants, not pandas) and only occur naturally in shaded mountain stream beds in parts of Japan. Commercial growers in Taiwan, China and the US are limited to small areas which stay between 45 and 70 degrees Fahrenheit. In fact, according to a BBC article, most experts agree that it is the most difficult plant to grow commercially.
“It's a water loving plant, but it does not grow completely submerged in water like a water lily or something,” explains Professor Carol Miles of the Department of Horticulture at Washington State University. “In general, water flows over the crop, so it's grown in water beds and that's not something we commonly do in North America.”
However, there is some good news about all that horseradish you’ve accidentally eaten. Along with its rarer, greener counterpart, it was originally farmed for its medicinal properties. However, unlike a lot of herbal remedies which continue to be popular to this day, there was a lot of truth to the claims.
Horseradish contains Vitamin C, calcium, potassium, manganese, magnesium and zinc. It helps regulate the transfer of nutrients between cells and can also relieve digestive issues. It has even been known to help alleviate the symptoms of urinary tract infections.
Its Asian cousin is clutching some similarly impressive credentials. Wasabi is also rich in Vitamin C, calcium and potassium but it also boasts a type of compound called isothiocyanates which can help alleviate the symptoms of allergies and asthma. In fact, wasabi proponents might even try and convince you that this particular compound prevents tooth decay.
Of course, the scarcity of wasabi makes it far more expensive. Horseradish costs around $25 dollars per kilo whereas wasabi costs a hefty $160 per kilo. So it’s not only the hardest plant to grow in the world - it’s also one of the most expensive to buy. Now it seems a little more obvious as to why a restaurant might prefer to use processed horseradish rather than genuine wasabi.
However, another reason to opt for an alternative is wasabi’s troublesome temperament as a foodstuff. Once exposed to air, wasabi can lose its flavour in just 15 minutes. It therefore has to be carefully prepared and if it spends too long idling on the worktop or looking pretty on the pass, all that money will have been wasted.
But for any aspiring food critics out there, you might have noticed that there is one major difference which hasn’t yet been mentioned. While horseradish provides a kick in the mouth of equestrian proportions, wasabi provides a far more tempered tang. They are indeed both members of the Brassicaceae family (which includes cabbages, broccoli and - not unsurprisingly - mustard) however, wasabi has a far more delicate taste.
So there you have it. Next time you find yourself tucking into some black cod with a friend at a wooden-walled pan Asian restaurant or sharing sashimi on a date at a sushi bar, you can let it be known that the vast majority of wasabi is actually horseradish in disguise. Oh, and that delicious crispy seaweed you always get at a Chinese buffet? That’s just deep fried cabbage. Sorry.