This is one of the greenest wasabi I’ve seen in years, intense green color and so why is it so green?
The green color of leaf vegetables is due to the presence of the green pigment chlorophyll. Chlorophyll is affected by the pH, and it changes to olive-green in acid conditions, and to bright green in alkaline conditions. Some of the acids are released during the grinding of the wasabi on the copper grater.
Grown primarily in Japan wild wasabi are only found mountainside in stream beds and sandy rivers. Cultivated wasabi plants are similar to the wild-type variety, comprise a cluster of long-stemmed heart-shaped leaves and delicate, spring-blooming, white flowers branching from a gnarled, thick, root-like stem known as a rhizome.
Wasabi grown under semi-aquatic conditions are called sawa, while those grown in fields are called oka Sawa is considered higher quality, as they produce larger rhizomes, thereby often cultivated for culinary purposes. Oka is largely cultivated for nutraceutical purposes, such as herbal supplements.
Due to the high volatility of the flavor compounds, after grating the rhizome, the heat will only last for, at most, fifteen minutes, whereas horseradish-based wasabi can be left overnight and still retain its heat.
Additionally, though the chemical makeup of horseradish and wasabi may be similar, it is different enough that each has a unique flavor profile. Both horseradish and wasabi rhizomes contain thioglucosides, a sugar glucose with sulfur-containing organic compounds.
Maceration of the rhizome, such as by grating, breaks the cell walls and releases these thioglucosides, as well as an enzyme known as myrosinase. Myrosinase is responsible for breaking the thioglucosides into glucose and a complex mixture of a class of compounds called isothiocyanates.
Horseradish and wasabi contain varying isothiocyanate amounts and compositions. There are 1.9g total isothiocyanates per kilogram of horseradish, as opposed to 2.1g/kg in wasabi. The most abundant and stable of these compounds, allyl isothiocyanate, gives real and imitation wasabi its infamous pungency . The next most abundant isothiocyanate compound is 2-phenylethyl isothiocyanate, which is only found in horseradish . All other types of isothiocyanates exist in higher concentrations in wasabi than horseradish.