Varietal Differences in Quercetin Contents and Antioxidant Capacities of Onions

Abstract

北海道産タマネギ9品種のケルセチン配糖体，ORAC法による抗酸化能測定値および総ポリフェノール含有量を比較した．その結果，ケルセチン配糖体含有量は31.24±2.15から133.7±8.88 μmol/100g FWの範囲，ORAC値は878.1±44.7から2 075.6±168.6 μmol TE/100g FWの範囲，総ポリフェノール含有量は22.65±1.41から48.44±1.35mg GAE/100g FWの範囲であり，いずれも「月交24号」が最も高値を示した．また，タマネギ中の主要な抗酸化物質はケルセチン配糖体であり，「月交24号」はケルセチン配糖体を高含有する品種であるため，高い抗酸化能を示したと考えられた． 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 μmol/100g fresh weight. ORAC values and total polyphenol contents ranged from 878.1±44.7 to 2 075.6±168.6 μmol Trolox equivalent/100g fresh weight, and 22.65±1.41 to 48.44±1.35mg gallic acid equivalent/100g 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.