The secret of enjoying fresh wasabi lies in the grating of the rhizome to release the pungent zingy flavour. Fresh wasabi rhizomes are a rare and precious culinary commodity prized by sushi dining chefs. The best grater to use is the traditional Japanese ‘Samegawa-Oroshi’-Sharkskin Grater but these are quite expensive to purchase. However, you don’t have to worry as you can always use any fine grater available.
So, to begin the grating process you first wash the rhizome in cold running water and lightly trim off only the black bumps on the surface. This blackness is a result of a natural process due to air oxidation taking place at the surface of the rhizome. Carefully, peel off the outer thin black layer on the rhizome, (if any) you find by using a potato peeler or something similar. Then begin grating from the thicker side a this section is fresher and yields a more zingy taste to give that beautiful pale green coloured wasabi paste.The freshly grated wasabi paste should not be stored in a metallic container, it is best to use an unsealed ceramic basin. During the grating process, a pinch of sugar can be placed on the grater to give the wasabi a milder flavour.
The remaining rhizome can be preserved for at least one month in a refrigerator by wrapping it up in a damp towel. Remember to replace the cloth every 2-3 days to keep the rhizome in good condition. If wanted, the whole rhizome can be grated all at once to produce small parcels of wasabi paste wrapped in ‘cling film’ and stored in the freezer until required.
It is better to start grating the rhizome from its top end by swirling around the whole root to produce the best aroma and pungency as each part of the rhizome has slightly a different flavour profile and associated pungency. This approach will maximise the blend of the whole root. Once grated, the wasabi must be kept chilled in a refrigerator to preserve its pungency which dissipates within two hours or at room temperature the pungency will completely disappear in the space of 15 minutes.
Freshly grated wasabi on a traditional Japanese Sharkshin
The wasabi rhizome should be maintained in a chilled state and not frozen otherwise its fibre will be damaged. If wishing to keep the grated wasabi paste for longer than one week, then the colour will darken and its pungency and smell will change due to the air oxidation of allyl isothiocyanate. It is better to grate the rhizome as and when required to eat immediately.
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