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.