Temperature-dependent kinetics of unsaturated fatty acid methyl esters: Modeling autoxidation mechanisms

Understanding the oxidative stability of unsaturated fatty acid methyl esters (FAMEs) is critical for food preservation and industrial applications. This study extends our first-principles kinetic model (Food Res Int 2023, 173, 113289) by integrating mechanistic insights into the temperature-dependent shift from bimolecular to monomolecular hydroperoxide decomposition. Our approach, based on experimental evidence of a critical temperature and the parameterization of the equilibrium between free and hydrogen-bonded hydroperoxides, was validated against data spanning 7 °C to 200 °C (391 measurements). Without further fitting, the model achieves R² values between 0.613 and 0.896. On curated datasets, the Concordance Correlation Coefficient exceeds 0.78, the Prediction Interval Coverage Probability is over 50 %, and relative deviation errors below 30 %. Below 80 °C, bimolecular pathways dominate, whereas monomolecular processes prevail at higher temperatures, influencing induction times and oxidation rates. These findings lay the groundwork for predictive models that optimize shelf life by integrating FAME composition and temperature history.