L‐ascorbyl palmitate and endogenous micronutrients in vegetable oils provide synergistic antioxidant activities: Micronutrient species and concentration.

In the present study, antioxidant impacts of L‐ascorbyl palmitate (L‐AP) on 14 kinds of typical vegetable oils were studied, whose ratios of C18:1 to C18:2 ranged from 0.15 to 9.57. Regression analyses between vegetable oils and their micronutrient‐free counterparts revealed that the antioxidant capacity of L‐AP was closely related to concentrations of α‐, γ‐, and δ‐tocopherols instead of fatty acid compositions. Binary mixtures consisting of L‐AP and α‐, γ‐, or δ‐tocopherols exhibited desirable synergistic antioxidant effects in comparison with individual species. The optimal synergistic effects were found at ratios of L‐AP to α‐, γ‐, δ‐tocopherols, being 1:2–1:4. Further EPR spin trapping test figured out that the combined antioxidants reduced the total amount of spin adducts significantly during lipid oxidation, which were contributed by regenerating tocopherols from L‐AP. The results will highlight the application of L‐AP in protecting packed cooking oils after opening and during cooking. Practical applications: Vegetable oils packaged in 4–5 L bottles are one of the most important forms for home cooking. Although deoxygenation techniques are applied to increase their shelf life during storage, they will experience a more violent oxidation reaction after opening. The oils are typically oxidized to rancidity before ending up in consumption. L‐AP was therefore involved into the vegetable oils to prevent them from oxidation during uses. The results of study can help companies to select the optimal L‐AP addition amount according to different endogenous tocopherol types and contents in the target oil in order to extend the use life of the vegetable oil. [ABSTRACT FROM AUTHOR]