Influence of Antioxidant Concentration, Temperature, and Saturated Lipid Content on α-Tocopherol Stability in Oil Blends
Abstract
Oxidative stability remains a critical challenge in lipid-based food systems, where tocopherols serve as key natural antioxidants. The effectiveness of α-tocopherol, however, is strongly influenced by its concentration, storage temperature, and lipid matrix composition. This study systematically investigated the stability and antioxidant efficacy of α-tocopherol in stripped soybean oil (SSO) and SSO–medium-chain triglyceride (MCT) blends under accelerated oxidation conditions. It was hypothesized that α-tocopherol exhibits a concentration-dependent protective effect, further modulated by temperature and saturated lipid content. Oxidation kinetics were evaluated across a wide range of α-tocopherol concentrations (25–500 µM), temperatures (45 °C and 55 °C), and MCT proportions (0–75%) using lipid hydroperoxide value and headspace hexanal analysis. A clear dose-dependent antioxidant response was observed, with increasing α-tocopherol concentrations significantly extending the lag phase period, although antioxidant efficacy plateaued above approximately 300 µM. Arrhenius-based kinetic modeling demonstrated that the presence of α-tocopherol increased the activation energy of oxidation and extended the predicted shelf-life at 25 °C to approximately 165 days in SSO samples containing 500 µM α-tocopherol. In addition, increasing saturated lipid content synergistically enhanced α-tocopherol performance, with the lag phase increasing from 6 to 32 days as MCT content rose from 0% to 75% in the presence of 100 µM α-tocopherol. These findings provide mechanistic and quantitative insight into how antioxidant concentration and lipid matrix composition interact to control lipid oxidation and offer a practical framework for optimizing antioxidant strategies and predicting shelf-life in lipid-based food formulations.
Keywords
Antioxidant, Arrhenius Kinetics, Lipids, Oxidation, Saturated Fatty Acids, Tocopherol
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