Brassica vegetables contain high amounts of glucosinolates, which contribute to the beneficial health effects of their consumption. Processing of such vegetables in domestic food preparation or industrial processing will influence levels of glucosinolates considerably and thus affect their health-protective capacity. This study demonstrates the effects of chopping of raw Brassica vegetables on their glucosinolate composition. Limited breakdown of aliphatic glucosinolates in cabbage was found, whereas unexpected increased levels of indolyl glucosinolates were detected after chopping and storage of cabbage and broccoli under ambient conditions. In chopped white cabbage a 15-fold increase of 4-methoxy- and 1-methoxy-3-indolylmethyl glucosinolates was noted after 48 h of storage. Chopping and storage of broccoli resulted in a strong reduction of most glucosinolates, except for 4-hydroxy- and 4-methoxy-3-indolylmethyl glucosinolates, which increased 3.5- and 2-fold respectively. The myrosinase-mediated hydrolysis of glucosinolates appears to be counteracted by a post-harvest increase of some indolyl glucosinolates. In this paper we propose a mechanism of stress-induced increase of glucosinolates, which plays an important role besides the well-known breakdown mechanism.
© 2001 Society of Chemical Industry