There is a Wasabi restaurant in Taj Hotel in Bombay. We can never afford to go to such hotels but heard the name in context of the terrorist attack on the hotel. Actually Wasabi is root stem like ginger and its name is Wasabia Japonica. All this indicates that the whole thing is about Japanese food especially Sushi. Wasabi is used as one of the ingredients in the form of paste of pistachio-green color. It adds the zing to the food.
The real thing is in the short supply even in Japan its home itself. So at most places what is served as wasabi paste is most likely just a mix of European horseradish, mustard, and food coloring.
As a member of the Cruciferae family, it is related to such plants as cabbage, cauliflower, broccoli, and mustard. Its distant cousin European horseradish (Armoracia rusticana) often substitutes for it.
Wasabi grows naturally in mountain streambeds, and the Japanese have cultivated it for more than a millennium. Wasabi grown in semiaquatic conditions is known as sawa, whereas wasabi grown in fields is called oka. The stream-grown wasabi produces larger rhizomes and is generally considered to be of higher quality.
The heat of real Wasabi lasts at the most for 15 minutes after grating. But its imitations like horseradish stays for long periods. The components of both wasabi and horseradish can be stabilized by acids, such as vinegar or lemon juice.
The key chemicals that give wasabi its characteristic heat and flavor aren’t present until the wasabi is macerated. When the cell wall is disrupted, it releases the enzyme myrosinase, which hydrolyzes glucosinolates, a group of sulfur-containing glucose derivatives, to produce isothiocyanates that provide wasabi’s spicy zing. The most abundant of these is allyl isothiocyanate. Horseradish has a different profile of isothiocyanates. One of the by-products of the myrosinase reaction is glucose.
The flavor is affected by how finely the wasabi is grated. The traditional way to grate wasabi is with a sharkskin grater, called an oroshi, which resembles fine sandpaper. Because the flavor and heat dissipate so rapidly, it’s best to grate it as you need it.
Scientific studies carried out by Savage and his coworkers show comparison of seven isothiocyanates in wasabi and horseradish. The horseradish contained 1.9 g total isothiocyanate/kg, whereas wasabi contained nearly 10% more (2.1 g/kg). Allyl isothiocyanate was the major component in both. The second most abundant isothiocyanate was 2-phenylethyl isothiocyanate, but it was found only in the horseradish. It, therefore, probably plays a major role in the flavor differences between the two plants. Every other isothiocyanate was present at higher concentrations in wasabi than in horseradish.