Effect of Olive Pruning Wood Extract on Lipid Oxidation in Sunflower Oil
Abstract The production of high quality natural Antioxidants from olive pruning wood extracts and their application to prevent the oxidation of vegetable oils were evaluated. The production of antioxidants from branches of olive pruning wood (OPW) using Soxhlet extraction and ethanol was optimized, evaluating the use of dry and fresh OPW, with extraction of an initial mass of 1 and 3 g and extraction times of 2, 4 and 8 h. For the evaluation of the antioxidant properties of the OPW extracts (OPWEs), the 2.2-diphenyl-1-picrylhydrazyl (DPPH) radical bleaching and ORAC-FL assays were performed. Additionally, the phenolic profile of the OPWEs was obtained by using HPLC-DAD, and the total phenolic composition was quantified by the Folin-Ciocalteu assay. The OPWE obtained from dry OPW using 1 g of initial mass showed the highest content of phenolic compounds and better antioxidant capacity compared to the OPWE obtained from fresh OPW. Both extracts showed the same profiles, but the OPWE obtained from dry OPW showed twice the concentrations of catechin (1.00 g 100 g−1 OPWE) and oleuropein (12.59 g 100 g−1 OPWE). Low concentrations of optimized OPWE showed activity against lipid oxidation of sunflower oil, measured by the peroxide value obtained by microwave and forced air oven heating. Under high temperature conditions and concentrations, the results suggest that OPWE may present the opposite effect.