Composition and content of flavonol glycosides in green beans and their fate during processing

Four varieties of green bean (Phaseolus vulgaris) were analyzed for flavono l composition and content. Two flavonol conjugates, not previously reported in green bean, were found in three of the varieties. These are quercetin 3 -O-(2(G)-beta-D-xylopyranosylrutinoside) (1), (1.0-2.0 mu g/g of fresh weig ht) and the corresponding kaempferol analogue (2) (0.3-0.7 mu g/g), The maj or flavonol component in all of the varieties was quercetin 3-O-glucuronopy ranoside (3) (3.5-15.1 mu g/g) with lesser amounts of quercetin 3-O-rutinos ide (4) (0.2-4.3 mu g/g) and kaempferol 3-O-glucuronopyranoside (5) (0.5-1. 3 mu g/g). Kaempferol rutinoside (6) was detected in only one variety (0.8 mu g/g). Commercial processing, such as canning, did not result in chemical breakdown of the conjugates, although between 8.8 and 24.4%, depending on the conjugate, was leached into the cooking water.