Phenolic content and antioxidant capacity of Philippine potato (Solanum tuberosum) tubers

Four potato (Solanum tuberosum) varieties - Bengueta, Ganza, Igorota and 125411.22 - were analyzed for total phenolic content and antioxidant activities to provide baseline data for Philippine potato varieties. Bengueta had the highest phenolic content with 50.0 +/- 1.5 mg gallic acid equivalent (GAE)/100 g (dry basis, DB). It also had the highest DPPH radical scavenging activity with an EC50 value of 30.6 +/- 3.6 mg/mL (DB). The potato variety 125411.22 had the highest reducing power with EC50 equal to 66.2 +/- 1.6 mg/mL (DB), while Igorota had the highest iron-chelating capacity with an EC50 of 11.0 +/- 3.2 mg/mL (DB) and the best inhibitory action against linoleic acid oxidation at 95.4 +/- 2.2% at 50 mg/mL sample concentration. Methanolic potato extracts had better antioxidant activity than alpha-tocopherol and better iron chelating capacity than ethylenediamine tetraacetic acid (EDTA). Significant (P < 0.05) negative correlation (R = -0.542) was observed between total phenolic content and the EC50 values for DPPH radical scavenging activity, but none between total phenolic content and reducing power, iron-chelating capacity and total antioxidant activity. (C) 2008 Elsevier Inc. All rights reserved.