Studies on the Stability of Dried Wasabi Flour

Abstract

Wasabia japonica root pieces were dried at below 55°C. Wasabi flours were stored in sealed vessels, and isothiocyanate (itc) contents in the hydrolysates of the flours were determined by headspace analysis during the storage. When the flours were stored at 20°C and 30°C, the contents of iso-propyl, sec-butyl, n-butyl, allyl and 3-butenyl itcs all decreased, especially at 30°C storage, the amount of iso-propyl itc reduced by half after 1 week, and those of the other itcs had the same results after 4 weeks. In Wasabi flours which had the decreased itc contents, these contents was restored by the addition of trace amount of L-ascorbic acid as myrosinase activator. Wasabi flour with low itc contents and horseradish flour were mixed at several ratios to prepare so called "Wasbiko". Several itc contents and mixing ratio bore good correlation curves. Accordingly, mixing ratio of Wasabi flour and horseradish flour in the "Wasabi-ko" will be assumed similar to the case of "Wasabi" powder (so called "Kona-wasabi") by the calculation of Rg, x and y values.