Synergism and antagonism mechanisms of β-carotene, γ-oryzanol, and β-sitosterol on oxidative stability of walnut oil.

The antioxidant capacity and mechanism of a binary mixture of natural antioxidants β-carotene, γ-oryzanol, and β-sitosterol were evaluated using purified walnut oil as a substrate. Synergistic effects were identified using Rancimat method, while free radical generation was examined by ESR. Dynamic changes in antioxidants and oxidation products were analyzed by GC-MS and HPLC. Results indicated that interaction effects were influenced by different ratios and concentrations. Notably, β-carotene and γ-oryzanol exhibited a significant synergism during oxidation. Specifically, γ-oryzanol not only scavenges lipid radicals but also has the potential to regenerate β-carotene, thereby restoring its antioxidant function. In addition, γ-oryzanol produces oxidation products with antioxidant activity that further contribute to radical inhibition. Daily storage tests also confirmed that the synergistic antioxidant binaries effectively extended edible oil shelf life.