Impact of Phenolic Content on Antioxidant Activity in Yellow and Purple-fleshed Potatoes Grown in the Czech Republic

Abstract

ABSTRACT Purple-fleshed potatoes cultivars are new on the Czech market. Intensive trials about growing purple-fleshed potato cultivars in the Czech Republic are currently being carried out. Recently many articles deal with phenolic antioxidants and their contribution to the human health; thus the aim of this study was to determine the differences in total phenolic (TP) content and antioxidant activity (AA) between yellow (cvs. Impala, Karin, Dita, Saturna) and purple-fleshed (cvs. Valfi, Violette) potatoes grown in the Czech Republic in 2004 in four locations in 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 60% higher TP content than yellow-fleshed cultivars and AA content was double in purple-fleshed cultivars. A significant linear correlation between TP and AA was found (r2 = 0.747). Average TP content in yellow-fleshed cultivars was 2.96 GAE (gallic acid mg g−l DM) and in purple-fleshed cultivars 4.68 GAE was found. Average AA in yellow-fleshed cultivars was 11.26 AAE (ascorbic acid equivalent mg 100 g−1 DM) and in purple-fleshed cvs. 24.79 AAE. Purple-fleshed potatoes showed a lower variation among localities (6 % only). The results showed that AA of freeze-dried tuber matter is very low when compared to other plants or sources (wine, tea, chocolate and blueberries) although a high potato intake in humans by Czechs (72 kg capita−1 year−1) is considered.