Ascorbyl gallate ester: A dual-phase antioxidant with lipophilic-hydrophilic synergy for olive oil stabilization.

Virgin olive oil is susceptible to lipid autoxidation during storage and thermal processing, which deteriorates its nutritional quality and shortens shelf life. Conventional water-soluble natural antioxidants including L-ascorbic acid and gallic acid suffer poor oil miscibility, while synthetic antioxidants face growing food safety concerns. In this work, ascorbyl gallate ester (AGE), a novel dual-phase antioxidant with lipophilic-hydrophilic synergistic structure, was synthesized and systematically characterized. Its radical scavenging performance was evaluated via 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6- sulfonic acid) (ABTS) assays. At a concentration of 100 μM, AGE achieved DPPH and ABTS radical scavenging rates of 87.2% and 89.5%, significantly higher than gallic acid, TBHQ and L-ascorbic acid. A 12-day accelerated oxidation test at 80 °C demonstrated that the AGE group maintained the lowest peroxide value and p-anisidine value after thermal treatment, and gas chromatography (GC) results indicated AGE retained over 90% of C18 unsaturated fatty acids and drastically slowed lipid chain scission. The amphipathic structural features of AGE were confirmed by proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR) and Fourier-transform infrared spectroscopy (FT-IR). This study elucidates the structure-activity relationship of amphipathic AGE, and this compound possesses great application potential as a high-efficiency stabilizer for edible oil preservation.