DISTRIBUTION OF QUERCETIN CONTENT IN DIFFERENT RINGS OF VARIOUS COLORED ONION (ALLIUM-CEPA L) CULTIVARS

Representative cultivars of different coloured onions were compared to determine the extent of differences in the distribution of free and t otal (bound and free) quercetin among different onion rings. The dry s kin, outer rings, and inner rings were separated and extracted with et hanol to obtain quercetin glycosides (bound form) that were then hydro lyzed to free quercetin. Free quercetin was used as the standard for q uantification by reverse phase high performance liquid chromatography (HPLC). Significant difference (P = 0.05) in total quercetin content w as observed between the dry skin and inner rings (edible parts). A dec rease in total quercetin content was observed from the dry skin to inn er rings. The highest total quercetin concentration was observed in th e dry skins of 'Red Bone' (30.66 g kg(-1) dry weight) while 'Contessa' contain the least amount (0.094 g kg(-1) dry weight). Total quercetin content in outer rings (1-2) in 'Kadavan' was high highest (345.51 mg kg(-1) fresh weight); however, trace amounts were observed in 'Contes sa'. Inner rings (5-6 and 7-10) contain less total quercetin in all th e cultivars. Outer rings (cataphylls) of all the cultivars except 'Tex as Grano 1015Y' and 'Contessa' contain moderate amounts (2.5-16 mg kg( -1) fresh weight) of free quercetin. 'Red Bone' skin contain the highe st amount of free quercetin (20.64 g kg(-1) dry weight). Quercetin dis tribution based on fresh and dry weight method was also evaluated.