Applicability of a Voltammetric Assay Based on the Electroreduction of Oxygen to Evaluate the Antioxidant Capacity of Pequi (Caryocar brasiliense Camb.) Pulp

This study aimed to use a differential pulse voltammetric (DPV) assay, based on the electroreduction of oxygen, to evaluate the antioxidant capacity of pequi pulp. The results were expressed in coefficient of antioxidant capacity (K), at different pH values and in trolox equivalent antioxidant capacity (TEAC), and were compared to the 2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) spectrophotometric assays. The principal component analysis showed higher K for pequi pulp extract and pH tending to 7.15. The antioxidant capacity was related to the presence of gallic acid in its composition. Regarding the TEAC value, the best result was obtained by the DPV test (53.43 ± 5.14 µmol trolox g-1 pulp). The pequi pulp showed antioxidant capacity, compared to the standard antioxidant compounds evaluated. It was concluded that the voltammetric protocol was efficient to assess the total antioxidant capacity of pequi pulp and can be an alternative to conventional spectrophotometric assays, for the analysis of food matrices.

本研究旨在采用基于氧气电还原的差分脉冲伏安法（differential pulse voltammetric, DPV）检测法，评估皮奎果肉的抗氧化能力。本实验在不同pH值条件下开展，研究结果以抗氧化能力系数（K）以及Trolox等效抗氧化能力（TEAC）表征，并与2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)（ABTS）、2,2-二苯基-1-苦基肼基（DPPH）分光光度检测法进行对比。主成分分析结果显示，皮奎果肉提取物的抗氧化能力系数K更高，且当pH值趋近于7.15时效果最优。该抗氧化能力与其成分中的没食子酸含量密切相关。就TEAC值而言，DPV检测法获得了最优结果（53.43 ± 5.14 μmol Trolox·g⁻¹果肉）。相较于本次评估的各类标准抗氧化化合物，皮奎果肉展现出了显著的抗氧化能力。本研究得出结论：该伏安法方案可高效评估皮奎果肉的总抗氧化能力，可作为传统分光光度检测法的替代方案，用于食品基质的分析。