Changes of glucosinolates and isothiocyanates in Yamatomana during heat cooking

Abstract

Yamatomana (Brassica rapa L. Oleifera Group) is a traditional cruciferous leaf vegetable in Japan. It contains several types of glucosinolates, which are converted anti-inflammatory compounds, isothiocyanates, by myrosinase action. Although Yamatomana is usually eaten after heating, the changes of these compounds have not been studied. In this work, changes of glucosinolates and isothiocyanates in Yamatomana during heat cooking were analyzed.
Yamatomana leaves were heated by several ways and then freeze-dried. Isothiocyanates were determined by HPLC after derivatization with 1,2-benzenedithiol. For the determination of glucosinolates, they had been converted to isothiocyanates by adding myrosinase.
Although all glucosinotes were converted to isothiocyanates in fresh Yamatomana leaves, no isothiocyanates were found after 1-min heating. Glucosinolates decreased during heating process. Sodium chloride significantly suppressed the decrease of glucosinolates.