Determination of phenolic content, composition and their contribution to antioxidant activity in specialty potato selections

In order to identify elite parental lines for use in breeding programs emphasizing human health benefits, specialty (colored) potato selections from the Texas Potato Variety Development Program were analyzed for antioxidant activity (AA) using 2,2-diphenyl-l-picrylhydrazyl (DPPH) and 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical assays, total phenolic content (TP) using Folin-Ciocalteu reagent (FCR), and phenolic composition using high performance liquid chromatography (HPLC). Total AA ranged from 157 jig trolox equivalents (TE)/gfw to 832 pg TE/gfw and 810 jig TE/gfw to 1622 mu g TE/gfw using the DPPH and ABTS assays, respectively. TP ranged from 221 pg chlorogenic acid equivalents (CGAE)/gfw to 1252 pg CGAE/gfw. Selection CO112F2-2P/P had the highest AA and TP, Purple flesh selections had the highest AA and TP, followed by red flesh and yellow flesh selections. Selections with similar flesh color did not differ significantly in AA and TP. A significant positive correlation was observed between AA and TP. Chlorogenic acid, gallic acid, catechin, caffeic acid, and malvidin-3-(p-coumaryl rutinoside)-5-galactoside were the major polyphenols identified. Chlorogenic acid accounted for 50 to 70% of TP, followed by catechin, gallic acid and caffeic acid. Contribution of individual phenolics in specialty potatoes to AA was calculated using pure standards. Chlorogenic acid contributed 28 to 45% to AA, followed by gallic acid, catechin and caffeic acid.