Preparation and Why Such a Fine Paste?
To obtain the best flavour, texture and heat of sawa Wasabi the rhizome must be ground into a fine paste. In Japan the traditional method for grating Wasabi uses a sharkskin grater or “oroshi”. If a sharkskin grater is not available, ceramic or stainless steel surfaces can be used. The important component of the grater is the teeth or nubs. Smaller teeth produce a finer paste that increases the unique heat and flavour of fresh Wasabi. Grating Wasabi releases volatile compounds, called isothiocyanates that gradually dissipate with exposure to the air. These compounds are not found in Wasabi until after the cells of the plant are broken up and turned into a paste. The finer the paste the more chemical reactions take place. Using a Wasabi grater and keeping the rhizome perpendicular to the grating surface minimizes exposure to the air. In this way, the volatile compounds are allowed to develop with minimal dissipation. This combination of natural volatiles, consistency and texture distinguish fresh wasabi from the imitation products of powdered and paste horseradish, which have been mixed with Chinese mustard and green food colouring.