Kinetic Simulation of Lipid Oxidation and Lycopene Antioxidant Activity in Tomato Pomace Using ANSYS Chemkin

This study investigates the kinetics of lipid oxidation and the antioxidant activity of lycopene in tomato pomace using a combined computational-experimental approach. A reaction mechanism describing initiation, propagation, hydroperoxide formation, and radical scavenging was implemented in ANSYS Chemkin 2025 R2 and simulated under controlled conditions at 50, 70, and 90 °C for up to 12 h. The model was validated using experimental measurements of linoleic acid, lycopene, and hexanal obtained from thermally treated tomato pomace. The results showed a strong temperature dependence of oxidation processes, with minimal changes at 50 °C and a transition to a propagation-dominated regime at 90 °C. Linoleic acid degradation reached 18.17% after 12 h at 90 °C, accompanied by a significant increase in hexanal formation, while lycopene loss remained below 5%. The model accurately reproduced experimental trends, with high correlation coefficients (R² = 0.9761 for linoleic acid, 0.9899 for lycopene, and 0.9982 for hexanal). Hydroperoxides were identified as key intermediates, accumulating prior to decomposition into volatile products. The results demonstrate that the proposed kinetic model provides a reliable tool for predicting lipid oxidation behavior in tomato by-products and highlights the critical influence of temperature on oxidative stability. Mean percentage errors ranged from 10.03% (hexanal) to 23.52% (linoleic acid), consistent with the complexity of the matrix.