Health benefits of phenolics are prompting vegetable breeders to identify cultivars with enhanced functional properties. Ten onion cultivars grown under North Indian conditions were evaluated for their total phenolics, flavonoids, quercetin and total antioxidant activity for two consecutive years. Total phenolics, flavonoids and antioxidant activity exhibited significant variation (P < 0.05) among cultivars. Red cultivars, namely Sel-383, N-53, Pusa red and Sel-402, constituted a high phenolic group, with a mean content higher than 100 mg/100 g gallic acid equivalents. Mean flavonoid content was highest in cultivars, Pusa red, Sel-402, H-44 and N-53 (>40 mg/100 g). White cultivars namely, Pusa white flat, Pusa white round and Early grano, consistently showed low phenolics, flavonoids and total antioxidant activity. Total antioxidant activity as determined by ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC) was highest in cultivars Sel-383, N-53, Pusa red and Sel-126. Over both consecutive years, phenolics correlated positively with total antioxidant activity (R2 = 0.95 FRAP and R2 = 0.87 CUPRAC). Over all red cultivars, Sel-383 and Pusa red are promising cultivars for incorporation in existing breeding programs for the production of onions with high antioxidant content.


Onion, being a major constituent of Indian diet, is a potential source of phenolics and flavonoids. Selection of the phenolic-rich cultivars, preferably the red ones with high antioxidant activity, can deliver a variety of health benefits. The breeders can use total phenolics and flavonoids as parameters to develop varieties with increased levels of target antioxidants.