Analysis of total antioxidant capacity in native andean potato cultivars (Solanum tuberosum L.)

Abstract

Both lipophilic and hydrophilic antioxidant capacities of 23 native Andean potato cultivars were determined using the Oxygen Radical Absorbance Capacity (ORAC). Hydrophilic antioxidant capacity (H-ORAC value) ranged from 33.02 ± 3.31 µmol of Trolox Equivalent/g of dry weight (µmol of TE/g of DW) to 343.69 ± 71.82 µmol of TE/g of DW. The lipophilic antioxidant capacity (L-ORAC value) varied from 1.49 ± 0.34 µmol of TE/g of DW to 5.77 ± 2.01 µmol of TE/g of DW. Total antioxidant capacity (TAC value) was calculated as the sum of the L-ORAC and H-ORAC values. L-ORAC values contribute only 1.06 - 8.59% of the TAC, indicating that hydrophilic compounds play a large part in the total antioxidant capacity of potato. Total phenolics (TP) of hydrophilic extracts were also measured using the Folin-Ciocalteu reagent. Among 23 potato cultivars, the total phenolics varied from 1.24 to 15.23 mg of Gallic Acid Equivalent/g of dry weight (mg of GAE/g of DW). The relation between TP and HORAC showed a positive and high correlation (r = 0.9873). It means that polyphenols are the main compounds responsible for the hydrophilic antioxidant capacity of potato.