Grating and Storing Fresh Wasabi Rhizomes

Fresh wasabi rhizomes are rare even in Japan; it can be quite hard to find them.  They are used by top sushi and fine-dining chefs who specialise in Japanese cuisine. If you are lucky to visit Japan and visit a sushi bar, you will find it an interesting experience. The sushi chef will grate your fresh wasabi using an oroshigane, also known as an oroshiki. These types of graters differ from European style graters because they allow for fine grating on the small spikes protruding out of the metal with no perforations. They are considered the best grater among professional chefs.

However, the grater commonly used in Japan is made from sharkskin and has been used for several centuries by traditional Japanese sushi chefs.  The sharkskin is the perfect tool for grating real wasabi and can bring out the unique zingy flavour and texture of the rhizome paste.  The sharkskin is fixed to one side of a small, wooden paddle.  This is the only grater that can achieve the best texture of wasabi and is even better than a microplane. However, if you do not have a sharkskin grater, you could always purchase a stainless steel grater from the Wasabi Crop Shop or use a plastic or ceramic grater.

We have used a stainless steel grater many times and it always produces an excellent paste with the special wasabi kick.

When you receive your fresh wasabi rhizome, slice off one end and press it against the grater making circular motions. In addition, you can lightly peel off the outer knobbly layer before grating.  At this point, only grate the required amount. Then, gather the wasabi paste into a pile using a bamboo brush which can be purchased from the wasabi crop shop.  This precious condiment can then be served with sushi, cooked meats potato as well as incorporating wasabi into all your favourite foods. 

However, the golden rule for wasabi paste is that you must let it stand for 5 minutes to allow the myrosinase to work and provide the wasabi kick. Then consume within 20 minutes to obtain the most optimum taste leaving the paste longer dissipate its unique flavour.

What to do with the fresh wasabi rhizome?

• When you receive the wasabi rhizome, carefully remove it from the vacuum pack.
• Once removed, rinse the wasabi rhizome with cold running water.
• Then carefully slice off the end tip or the crown and with a knife lightly remove the outer peel to the required amount.

• Using a suitable grater or a sharkskin paddle, grate the rhizome into a fine paste by pressing down on the grater and applying a circular motion.

• This produces a paste: gather it altogether into a pile using a bamboo brush or something similar.

• Keeping the wasabi paste in a small pile will minimise its exposure to the air.
• Let the wasabi paste stand for 5 to allow the myrosinase to work.
• Consume the fresh wasabi paste within 20 minutes to achieve its optimum flavour.

How to regenerate wasabi paste?

After 20 minutes the grated wasabi paste will lose some of its kick. To reactivate the wasabi mix it with a small amount of sugar or lemon juice to enjoy its flavour once more.

How do you store wasabi rhizomes?

• Wrap the wasabi rhizome in a damp towel or cheesecloth.
• Place the wrapped rhizome on an unsealed glass dish and transfer to a refrigerator.
• Every 2 to 3 days, remove the cloth, rinse it out with cold running water and rewrap the rhizome and place it back in the fridge.
• The proper storage of rhizomes will maintain freshness for up to four weeks.

What causes the rhizome to go black?

When you receive a fresh wasabi rhizome, you may notice some black patches and wonder what causes it.  This black layer is only a few millimetres thick on the rhizome’s outer surface and is due to a natural oxidation process which occurs over time.  The black colouration will not affect the freshly grated wasabi’s overall quality.

The black layer is nature’s way to lock the favour into the rhizome and therefore it is a good sign!

Furthermore, if you like, you can consume the black layer, but freshly grated wasabi is so much more enjoyable to eat.

In addition, the black layer protects the rhizome from the effects of oxygen in the atmosphere. It is easily removed by scraping with a knife or potato peeler, then proceed to grate into a fine delicious paste.

How to prepare aged rhizomes?

• To use old rhizomes, remove the thin oxidised black layer from the rhizome’s tip.
• Only remove the required black layer for the rhizome amount to be used.
• Wrap the rhizome in the same damp cloth paper and place on an unsealed glass dish to store in the refrigerator.
• The rhizome has an excellent chance to last a further few weeks by applying this process.
• It is best to keep the rhizome in the front section of the fridge so as not to freeze it, or it will become soft.
• The freezing of wasabi rhizomes affects their consistency and will reduce the zingy heat flavour.
• The rhizome quality is a condition of the cell walls and when activated, it will release the volatile compound allyl isothiocyanate and cause the wasabi kick.

How to order fresh wasabi rhizomes?

You can order wasabi produce from the Wasabi Crop Shop. If you are not sure how much to order, don’t worry; you can preserve the rhizome in the fridge. To do this just follow the above instructions and this should keep you right – enjoy your freshly grated wasabi rhizome and don’t forget the wasabi leaves, flowers and stems are also edible.

Enjoy Fresh Wasabi Grating!