Changes in Isothiocyanates of Wasabia japonica Roots by Drying

Abstract

Wasabia Jiponika roots were cut off into chips and dehydrated under air at low temperature or freeze dried. Isothiocyanates in the hydrolysates of fresh and dried materials were investigated by gas chromatography with FFD. (1) Nine kinds of isothiocyanate were detected in the hydrolysates of experimental samples: iso-Propyl, sec-butyl, n-butyl, allyl, 3-butenyl, 4-pentenyl, 5-hexenyl, 3-methylthiopropyl and β-phenethyl isothiocyanates. Two unknown volatile sulfur compounds were also detected. (2) Peak area % of 3-butenyl isothiocyanate to total peak areas were larger in dried materials than the fresh one. (3) Contents of allyl isothiocyanate were 0.217-0.324%(w/w) in the hydrolysates of fresh materials, and 0.856-1.335%(w/w) in those of dried materials. These contents decreased slightly by drying. (4) Contents of β-phenethyl isothiocyanate were small and about 1/10 of that in horseradish, which weren't changed practically by drying.