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 variety125411.22 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 α-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.