The antioxidant capacities, total phenolic contents (TPC), and total quercetin contents (TQC) of a red (Chenjujuck), a yellow (Sunpower), and a white (Grasier) onion cultivar were determined in this study. Onion was separated into edible portion and dry skin. In the case of edible portion, the yellow onion had the highest antioxidant activity, followed by the red onion. The white onion showed neither antioxidant activity nor quercetin compounds. On the other hand, the dry skin of the red onion showed higher antioxidant activity than yellow onion skin. The white onion skin had slight antioxidant activity, low TPC, and no quercetin compounds. In addition, the flavonoid compounds of the edible portion and dry skins of these colored onions were analyzed by UFLC(ultra-fast liquid chromatography). The major compounds were quercetin 3,4-diglucoside and quercetin 4- glucoside in yellow and red onion edible portion, whereas the major compounds in yellow and red onion skins were quercetin 4- glucoside, quercetin, and quercetin 3,4-diglucoside.

• Xiao Nan Yang(Department of Horticultural Sciences, Kyungpook National University)
• Enning Xu(Department of Horticultural Sciences, Kyungpook National University)
• Mi Jin Park(Department of Horticultural Sciences, Kyungpook National University)
• In Jong Ha(Onion Research Institute, Gyeongnam Agricultural Research and Extension Services)
• Jin Seong Moon(Onion Research Institute, Gyeongnam Agricultural Research and Extension Services)
• Young-Hwa Kang(Department of Horticultural Sciences, Kyungpook National University) Corresponding author