Differences in phenolic content and antioxidant activity in yellow and purple-fleshed potatoes grown in the Czech Republic

The aim of this study was to determine the total phenolic (TP) content and antioxidant activity (AA) in yellow (cvs. Impala, Karin, Dita, Saturna) and purple-fleshed (cvs. Valfi, Violette) potatoes grown in the Czech Republic in 2004 in four locations in precise field trials. TP content was determined by Folin-Ciocalteau assay and AA by DPPH assay both in freeze-dried tuber matter. Results showed a statistical significant difference in TP content and AA between yellow and purple-fleshed potatoes. Purple-fleshed cultivars showed higher TP content (by 60%) than yellow-fleshed cultivars; AA in purple-fleshed cultivars was twice as high as in yellow-fleshed potatoes. A medium linear correlation between TP and AA was found ( r2 = 0.747). Average TP content in yellow-fleshed cultivars was 2.96 GAE (g of gallic acid per kg dm); in purple-fleshed cultivars it was 4.68 GAE. Average AA in yellow-fleshed cultivars was 11.26 EAA (mg of ascorbic acid per 100 g dm) and in purple-fleshed cv. 24.79 EAA. Purple-fleshed potatoes showed a lower variation among localities (only 6%). Hence, regarding a relatively high potato intake by Czechs (72 kg per capita a year), contribution of potatoes, especially purple-fleshed, to total antioxidants intake should be considered.