Grating and Storing Fresh Wasabi Rhizomes 

Fresh wasabi rhizomes are a rare and precious culinary commodity prized by high level sushi and fine dining chefs of Japanese cuisine. Oroshigane means grating metal and also known as oroshiki are graters used in Japanese cuisine. These oroshigane differ from Western-style graters because they have finer grating patterns and use tin-coated copper plates with numerous small spikes on the surface of the metal. This type of graters is the best and are therefore used by leading chefs.

The grater commonly used in Japan are made from the surface of sharkskin. These graters produce a lot finer grating at the surface than the metal graters. However, you can use much less expensive graters made from other materials like plastic or ceramic.

1. Rinse the wasabi rhizome with fresh running water.
   
2. Cut off the end tip of the rhizome and with a knife remove the outer peel to the required amount.
   
3. Using a wasabi grater or a traditional Japanese sharkskin grater called an oroshiki (oroshigane); grate the wasabi rhizome into a fine paste using a light pressured circular motion.
   
4. The resultant wasabi paste should be placed in small amounts to minimise its exposure to the air.
   
5. Use the fresh wasabi paste within 5-10 minutes for the most optimal flavour.

Regeneration of wasabi

About 15-20 minutes after being grated, wasabi starts to lose some of its kick; it simply produces a burning sensation in the mouth. To regenerate the wasabi kick mix a small amount of sugar with the wasabi paste to enjoy its flavour once more.

Storage of wasabi rhizomes

After receiving the wasabi rhizomes, place them in a damp towel/cloth and transfer to a refrigerator. The wasabi rhizomes will remain fresh for up to four weeks.

Black rhizomes

The black layer which is only a few millimetres thick on the outer surface of the wasabi rhizome is due to an oxidation process which occurs overtime and does not affect the overall quality of the freshly grated wasabi. If the rhizome is not fresh, you will notice a white or grey colouration. This observation is associated with an unpleasant odour. Therefore, if the wasabi rhizome does not produce an unpleasant odour this indicates that the rhizome is acceptable for grating. The black layer is just nature’s way to keep the favour within the rhizome – so it is a good sign! You can consume the black layer, but you do not have to do this because freshly grated wasabi is much more enjoyable to eat. Conversely, the black layer protects the rhizome from the effects of oxygen in the atmosphere. The thin black layer is easily removed by scraping with a knife or potato peeler, then proceed to grating.

Preparing aged rhizomes

1. To use old rhizomes, just remove the thin black layer which has been oxidised from the length of the rhizome. Only do this with the required amount of rhizome to be used.
2. Wrap the rhizome back up in the same damp paper towel and place everything in an unsealed plastic bag to store in the refrigerator. By applying this process, the rhizome will be usable for at least another month.
3. The oxidation process will seal the exposed area on the rhizome from the scraping process.
4. It is worth noting to keep the rhizome in the front of the fridge so not to freeze it or it will turn soft.
5. The freezing process will affect the consistency and it will also reduce the zingy heat flavour.
6. The rhizome quality is based on the condition of the cell walls and if damaged will release the isothiocyanate which provides the wasabi kick. 

Ordering Wasabi