Oxidative Stability and Kinetics of Oxidation of Rosehip, Sunflower, Olive and Jojoba Oils

Lipid oxidation affects the quality and functionality of vegetable oils, and its progression depends largely on fatty acid composition and antioxidant content. Oxidation kinetics provide essential information about oxidative resistance in oils. The determination of activation parameters allows for the evaluation of oxidation susceptibility under thermal stress. Oxidative stability and oxidation kinetics at different temperatures of rosehip, sunflower, olive and jojoba oils were studied using both Rancimat and BQC-Redox System methods, enabling the calculation of kinetic constants and thermodynamic activation parameters for the process. BRS measurements showed an increase in total antioxidant capacity (TAC) with temperature in all samples, with olive oil presenting the highest TAC and jojoba the lowest at 298 K, while rosehip oil showed the lowest TAC at 373 K. Kinetic analysis revealed negative ΔS# values, indicating the formation of ordered transition states, and similar activation energies (ΔG# ≈ 56–58 kJ/mol), although jojoba displayed the highest ΔH# and ΔG#. Rancimat analysis at 373 K showed clear differences in oxidative stability: jojoba oil had the longest induction period, followed by olive, sunflower, and rosehip. These results correlated with PUFA levels. Principal component analysis (PCA) confirmed strong associations between induction period, fatty-acid composition, and kinetic parameters, demonstrating good agreement between the two analytical methods.