Buckwheat and Rosemary as Antioxidants in Soybean Oil: Comparison With Synthetic Antioxidant

This study examines the antioxidant potential of buckwheat and rosemary as an alternative to synthetic antioxidants in the oil industry. The methanolic extracts were analyzed for total phenol and flavonoid content, as well as antioxidant activity using the FRAP and DPPH methods. These extracts, along with the synthetic antioxidant TBHQ, were incorporated into soybean oil at varying concentrations (0 + 800, 200 + 600, 400 + 400, 600 + 200, 800 + 0 ppm (buckwheat + rosemary) and 50 and 75 ppm TBHQ) and oxidation tests conducted during 35 days storage at 60°C. Results showed that the extract of 800 ppm rosemary had the highest levels of phenolic (82.53 ± 6.39 mg GAE/g DW) and flavonoid (37.88 ± 3.08 mg RE/g DW) compounds. Antioxidant capacity of rosemary and buckwheat (800 ppm) were not significantly different from the TBHQ. Oil treatments with 800 ppm rosemary and buckwheat were more effective in postponing oxidation than the combination treatments. Oil samples with 800 ppm natural extracts were combined with synthetic antioxidant TBHQ at concentrations of 75 and 50 ppm, and oxidation indexes were evaluated. Findings demonstrated that this combination had a synergistic effect in postponing oxidation. The most effective treatment was 800 ppm buckwheat extract combined with 75 ppm of TBHQ for delaying oxidation.