Oxidative stability of pomegranate seed oil from blanched and microwave pretreated seeds: Kinetic and thermodynamic studies under accelerated conditions

This work aimed to evaluate the effects of blanching and microwave heating of pomegranate seed on the oxidative stability and shelf-life of ultrasound-assisted and ethanol extracted oil. Pomegranate seeds (cv. Herskawitz) were independently blanched at 95℃ for 3 min and microwave heated at 261 W for 102 s. The oil samples were subjected to accelerated oxidation (30, 40, and 50℃) to evaluate lipid oxidation kinetics, thermodynamics parameters, and estimate the shelf-life. The Arrhenius model and activated complex theory were used to estimate the energy for activation (E_a), enthalpy (ΔH^‡), entropy (ΔS^‡), and Gibbs-free energy (ΔG^‡), which varied from 6.2 to 8.59 kJ/mol, 3.69 to 6.38 kJ/mol, −146.62 to −155.06 J/K mol⁻¹, and 48.13 to 64.74 kJ/mol, respectively. According to the thermodynamics parameters, the lipid oxidation reactions in all oil samples were non-spontaneous, endothermic, and endergonic. Based on the developed Arrhenius models, blanching of pomegranate seed increased the oil shelf-life at 25℃ from 21 to 24 days, whilst microwave pretreatment did not change the oil shelf-life. Practical applications: Seed pretreatment is a novel approach that could be used to enhance the oil antioxidant properties. This study has established that the blanching of seeds is beneficial in enhancing the storability and shelf life of pomegranate seed oil (PSO). In addition, the study has demonstrated that antioxidant compounds and fatty acid composition are indispensable factors in PSO oxidation. The findings are useful in the design and establishment of PSO packaging, storage conditions, and application of modern technologies such as encapsulation to maximize its storability and retain the health-promoting properties.