Is wasabi the same as horseradish?
Wasabi and horseradish are different plants of the same family. However, most of the so-called wasabi sold outside of – and commonly even within – Japan is simply regular horseradish root cut with green food colouring and other things.
So unless you’re eating at a high-quality restaurant in Japan (or sourced it yourself from a speciality grocer), the wasabi that accompanies your sushi is almost certainly not real. Let’s take a look at why that is.
Horseradish root vs wasabi root
Wasabi is similar in many ways to common horseradish. In fact, wasabi is sometimes even referred to as Japanese horseradish. And in Japan, horseradish is known as seiyō wasabi – or western wasabi.
Horseradish and wasabi are both members of the Brassicaceae family of plants, which also includes the similarly spicy mustard and radish varieties. Both are generally consumed by grating or grinding the rhizome – its stem – which has a spicy taste that tickles the nose, as opposed to the tongue like chillies do.
Despite these similarities, there are noticeable differences in flavour that anyone who’s tried genuine wasabi could identify. Firstly, real wasabi isn’t as hot as horseradish. Its flavour is fresher, sweeter and more fragrant. Its colour is generally a more natural green, which makes sense as it’s not added artificially. Moreover, the shade of green varies greatly depending on the specific cultivar. (In fact, sometimes it isn’t even green at all.)
Whether or not it tastes better than horseradish is subjective, but wasabi certainly has a more complex and sophisticated flavour profile. So why is it usually replaced by its more aggressive western cousin?
Well, as you might expect, it mostly comes down to cost.
Unlike horseradish, which grows abundantly in temperate climates and up to 5 feet tall, wasabi is a comparably small plant that requires incredibly specific conditions to grow.
Wasabi comes from the stream beds in Japan’s mountain river valleys. Farmed wasabi must replicate this natural environment, where the crop can enjoy humid summers despite an intolerance to direct sunlight and temperatures above 20°C.
As wasabi is so difficult to cultivate, the genuine article has found it impossible to keep up with the exploding popularity of sushi across the world over the past two or three decades. Its rarefied status is reflected in its price. Whereas a kilo of horseradish sells for under $5 per kilo, high-end sushi restaurants can pay up to $300 for a kilo of wasabi.
By weight, wasabi is actually one of the world’s most expensive foods. Even just the seeds cost in the region of a dollar each. Unfortunately, another example of wasabi’s temperamental nature is that many of those pricey seeds simply fail to germinate.
Of course, when something so hard to produce costs that much money, you’ll want to ensure that you get the most out of it. Unlike commercial horseradish-based wasabi pastes, real wasabi is never prepared in advance.
A good Japanese restaurant will invariably grate the wasabi fresh to order. This isn’t just a matter of good taste. Another advantage of horseradish is that it has quite a long shelf life, even once grated and jarred. On the other hand, wasabi has a comparatively short expiration date. Once it’s been grated, you can expect it to start spoiling after about 15 minutes.
This also adds to the cost, at least in restaurants. It costs more to prepare something in small quantities ad hoc than it does to prepare a larger amount in advance.
So now you know why it’s so hard to get your hands on real wasabi. However, let’s be clear that we mean no disrespect to the humble horseradish. Just because it’s cheaper – and only because it’s easier to grow – doesn’t mean you should turn your nose up at this most misunderstood of vegetables. Click here for outstanding recipes that tame the spicy root, or try something a little more exclusive with Ernesto Iaccarino’s horseradish croquettes with turmeric and jasmine.
What is wasabi made of
Since wasabi is too rare and prohibitively expensive to satisfy demand, most commercial wasabi is made from horseradish and other ingredients. The wasabi paste that comes with your conveyor belt sushi is almost certainly horseradish, mustard powder, and green food colouring. If you’re lucky, it will use spinach extract as the colouring. This might better replicate the more herbaceous flavour of real wasabi – although you probably won’t be able to tell over the aggressive sharpness of the horseradish.
This is what even the most passionate sushi fans are consuming on a regular basis. In the US, more than 99% of what is sold as wasabi is actually this mix of horseradish, mustard and food colouring. That probably won’t surprise you after reading this article, but how about this? Even in Japan, an estimated 95% of wasabi products are also fake.