Your sushi wasabi is not wasabi
The wasabi served up with your lunchtime pack of sushi is almost certainly not real wasabi.
That pungent bright green condiment in a green sachet is most likely a mix of horseradish, mustard and green food colouring. Green food colouring is used because horseradish paste is not green... and wasabi is green.
The common, doughy green paste blobs in the corner of the plastic tray are also not really what they are called. They’ll be made from rehydrated powder from Japan, but they’re likely to contain little if any real wasabi powder.
New Zealand’s only supplier of real wasabi, Fenton Wood, says rehydrated wasabi powder often served in sushi bars was analysed by Lincoln University. It found ‘‘less than 1 per cent actual wasabi’’ in it.
‘‘Horseradish, peppers, fillers and lots of green colouring were plentiful,’’ Wood says.
Even a popular ‘‘wasabi’’ sold in tubes in supermarkets, which has Wasabi written down the front of the box, admits on the side it is ‘‘Japanese horseradish’’. It lists its ingredients as horseradish, lactose, sorbitol, corn oil, salt, water, artificial flavour, xanthan gum, turmeric, and artificial colours.
National sushi chain St Pierre’s admits the wasabi it puts in your lunch packet isn’t the real deal. But director Nick Katsoulis says this isn’t deception. He says the term ‘‘wasabi’’ is widely known, even in Japan, as a general term for a hot, green condiment.
‘‘And horseradish is a similar flavour. It’s not easy to tell the difference,’’ he says.
Katsoulis says cost and availability make it impossible to use real wasabi in a sushi chain. He buys wasabi powder from Kinjirushi, one of the largest wasabi sellers in the world. Its website states powdered wasabi ‘‘... is generally created by adding powdered mustard to dried horseradish powder and adding additional ingredients such as flavouring and artificial colours. This careful process increases flavour and the flavour’s longevity.’’
Wood says wasabi is rare and expensive. The pungency is only released when the plant material is cut, ground or crushed and it mixes with oxygen. The pungency disappears quickly, so that’s why many wasabi products take shortcuts.
He supplies restaurants with wasabi grown for him in NZ and sells a real wasabi paste under his Canterbury Coppersfolly business. In the paste he mixes real wasabi with lemon juice, oil, grapeseed oil, salt, citric acid. This keeps the pungency and flavour alive. Wood says in top Japanese restaurants, real wasabi rhizomes (found above the roots and below the leaves) are grated on the spot for diners; a dried sharkskin on a wooden board is used to create the green paste.
Tasting the real thing
Wood rubs a skinny Kiwi wasabi rhizome on sandpaper-like sharkskin and a pile of green paste builds up. We try it on his kitchen table.
We eat it on salmon sushi alongside the sushi shop’s rehydrated wasabi powder.
The two taste dramatically different. The familiar shop paste is pungent, nasal-ripping and, now you know, it’s probably mostly horseradish and mustard that’s what you can taste. The freshly grated Kiwi wasabi is completely different. For a moment there’s nothing, then it comes on strongly. It’s sweeter, cleaner and more vegetative. It’s more subtle and adds a kick that goes wonderfully with the fresh, raw salmon.