Abstract
Progoitrin is one of the glucosinolates which are abundant in Cruciferous vegetables and broken down with myrosinase when plant tissues are damaged through food processing or mastication. Progoitrin is reported to be degraded to either one of the two cyanide compounds or an isothiocyanate. The isothiocyanate is spontaneously cyclized to goitrin, which have been demonstrated to have an adverse effect on the thyroid. In this study, degradation of progoitrin from Chinese cabbage and rape was investigated in different food processing pH (pH 4, pH 6, and fermentation) and temperature of grinding (room temperature, 37 °C, and 100 °C). The amounts of the breakdown products and the remaining amount of progoitrin were monitored by GC-MS and HPLC, respectively. The generation of cyanide compounds was relatively favored in boiling temperature, pH 4, and pH 6.5 groups reflecting typical non-enzymatic degradation. However the fermentation showed a significant increase in goitrin formation. Goitrin was found to be the main product in fermentation group, comprising 45 % and 39 % of total breakdown products in room temperature and 37 °C groups, respectively. Considering large consumption of fermented Cruciferous vegetables such as Kimchi in Korea, the result warrants further research on the effect of fermentation and risk assessment of progoitrin.
