A Rapid Method for Determining the Pungent Principle in Root of Japanese Radish (Raphanus sativus L.)

Abstract

A rapid and simple method for determining 4-methylthio-3-butenyl isothiocyanate (MTB-ITC), a pungent principle in root of Japanese radish, was developed. Fresh root was grated by a food processor, and glucosinolates in the root tissue were hydrolyzed with endogenous myrosinase. Released MTB-ITC was extracted with methylene chloride, and analyzed by a gas chromatograph (GC) equipped with FID at constant column temperature.
Most of added sinigrin was quantitatively recovered as allyl isothiocyanate by the new modified method, indicating that the activity of endogenous myrosinase was high enough to hydrolyze all of glucosinolates to isothiocyanates. MTB-ITC contributed more than 95% of peak area detected on the chromatographic tracing. Methods of crushing root tissue affected the amount of MTB-ITC produced. MTB-ITC in methylene chloride was stable as long as it was kept at -20°C. Differences in MTB-ITC contents among radish cultivars were examined by the method.