Optimization of Monounsaturated Fatty Acids and Oil from Walnut Seed: Kinetics and Thermodynamics

Abstract

The optimization, kinetics and thermodynamics of oil and monounsaturated fatty acid extraction from walnut seed using hexane were investigated. The effect of process parameters were studied and optimized using response surface methodology. The experimental data was fitted into first order kinetic model and Van’t Hoff thermodynamic equation. The result revealed that the process parameters have significant effect on the yields of oil and monounsaturated fatty acid. The optimal conditions obtained were: solvent/solid ratio of 0.329mL/g and 0.342mL/g; extraction time of 46 minutes and 47 minutes; and extraction temperature of 42°C with optimal yields of oil and monounsaturated acid of 53% and 72% respectively. The kinetic study indicated that rate constant increases as temperature increases with activation energy of 38.59kJ/mol. The thermodynamics study showed that the changes in enthalpy and entropy were positive with negative change in Gibbs free energy. This indicates that the extraction of oil is spontaneous and feasible. 