Varietal differences in quercetin contents and antioxidant capacities of onions
2013
Watanabe, J. (National Food Research Institute, National Agriculture and Food Research Organization, Tsukuba, Ibaraki (Japan)) | Muro, T. | Yanagida, D. | Yamagishi, T. | Takano-Ishikawa, Y.
Contents of quercetin glucosides, antioxidant capacities (ORAC method), and total polyphenol contents were compared among 9 cultivars of onions harvested in Hokkaido, Japan. The contents of quercetin glucosides ranged from 31.24 +- 2.15 to 133.7 +- 8.88 micro mol/100g fresh weight. ORAC values and total polyphenol contents ranged from 878.1 +- 44.7 to 2075.6 +- 168.6 micro mol Trolox equivalent/100 g fresh weight, and 22.65 +- 1.41 to 48.44 +- 1.35mg gallic acid equivalent/100 g fresh weight, respectively. 'Tsukikou 24' showed the highest quercetin content, ORAC value, and total polyphenol contents. 'Tsukikou 24' was the richest in quercetin derivatives among the onion cultivars ; hence, it is suggested that its extract showed the highest antioxidant capacity.
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