Steam Volatile Isothiocyanates of Raw and Salted Cruciferous Vegetables

Abstract

The steam volatile isothiocyanates occurring in raw cruciferous vegetables and salted products thereof were investigated by a combination of gaschromatography and mass spectrometry. From the raw products the glucosinolates were extracted and subjected to enzymic hydrolysis by addition of mustard seed myrosinase and L-ascorbate; subsequently, steam distillation of the enzymically hydrolyzed glucosinolate extracts was performed. 2-Butyl, 3-butenyl, 4-pentenyl, 2-phenethyl and 5-methylthiopentyl isothiocyanate were found in all raw materials. In addition, allyl, 4-methylpentyl and 4-methylthiobutyl isothiocyanate were present in the distillates from species of Brassica campestris L. ssp. rapifera ; allyl, pentyl and 3-methylthiopropyl isothiocyanate in the volatile fraction from species of B. juncea (L.). In a parallel study, the salted materials which had undergone autolysis during the process of salting at their unadjusted pH, were subjected to steam distillation. A relatively large percentage of total isothiocyanates was observed in the steam volatile fractions obtained from the salted materials except for the product 'Zasai-zuke'. The isothiocyanates found as characteristic minor components in the raw materials were not detected in the salted ones. © 1979, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.