Variations in phenolics and antioxidants in Indian onions (Allium cepa L.)

Abstract

PurposeThe purpose of this paper is to provide a comprehensive evaluation of 34 onion genotypes for their antioxidant activity (AOX) content of phenolics, quercetin and pungency to enable selection of the best genotype for later experiments of variety breeding or to be used as a vector in the improvement of well‐established traditional genotype.Design/methodology/approachA comprehensive screening of 34 onion (red, pink and white) genotypes is carried out in order to determine the variation in phenolics, quercetin and total AOX as potential for breeding for their enhanced levels.FindingsThe AOX in red genotype with highest levels of phenolics is roughly three times higher than commercial white genotype. Pungency levels range from 3.12 to 10.48  μmoles pyruvic acid/g. Mean phenolic and quercetin content ranges from 60.1 to 1094.8 mg gallic acid equivalents/kg and 22.0 to 890.5 mg/kg quercetin, respectively. AOX in red genotype (expressed as μmoles trolox/g) ranges from 1.97 to 5.45 and 3.60 to 6.61 in ferric reducing antioxidant power and cupric ion reducing capacity assays, respectively. Selections, Sel‐383, Sel‐397, Sel‐61‐383, and Inbreds, I‐40, I‐80 and Burgundy are potential genotype with high pungency and AOX.Research limitations/implicationsAn improvement in breeding effort designed to increase the phenolics, quercetin and total AOX in onions (Allium cepa L.) provides selected material for analysis. Onion genotype and breeding lines with improved AOX are identified that would help breeders produce onions high in health promoting compounds.Originality/valueThe paper attempts to examine onion genotypes using standardized in‐vitro AOX assays.