Synergistic interaction between maillard reaction product and γ-tocopherol in enhancing the oxidation stability of flaxseed oil

The Maillard reaction during the foods processing and hot-pressed oils period generates potential antioxidant compounds that, along with endogenous antioxidants, enhance oxidation stability of oil. This study specifically investigated the interaction between 1-(1H-imidazole [4,5-C]pyridine-4-yl) ethenone (IMPE), a Maillard reaction product (MRP) isolated from a fructose-histidine system, and γ-tocopherol, the primary endogenous antioxidant in flaxseed oil. The results revealed a significant synergistic antioxidant effect between IMPE and γ-tocopherol. Accelerated oxidation tests (Schaal oven, Rancimat analyses) demonstrated that IMPE/γ-tocopherol mixture exhibited an extended oxidation induction period (7.84 h), substantially exceeding the additive effect expected from IMPE (4.12 h) and γ-tocopherol (5.01 h) individually, resulting in a synergistic degree (SD) of 1.25. Furthermore, density functional theory (DFT) calculations at the B3LYP/6-311+G(d,p) level revealed that the primary mechanism underlying this synergy is the regeneration of γ-tocopherol by IMPE, a finding corroborated by experimental degradation assays. These results elucidate a molecular mechanism for MRP-endogenous antioxidant interactions and provide valuable insights for designing effective composite antioxidant systems, particularly for enhancing the stability of hot-pressed oils.