Parametric study of oil extraction from African Star Apple (Chrysophyllum albidum) seeds.

Abstract

This study investigated the effect of extraction parameters such as particle size, temperature, and time on yield alongside the kinetic and thermodynamics variables for Chrysophyllum albidum. For the extraction, the oil yield increased as the extraction temperature and time increased, but the reverse was observed as the particle size increased. At the temperature of 55 °C, particle size of 0.55 mm, and extraction time of 150 min, the maximum oil yield of 14.98% was obtained. The extracted oil was analyzed and was found to have a saponification value of 134.64 mgKOH/kg, Iodine value of 82.53 mg I/g, peroxide value of 5mEq/kg, and acid value of 14.47 mg KOH/mg. In addition, the oil viscosity and specific gravity were 54.54 mm2 s−1 and 0.941, respectively. Hyperbolic, second-order, and Elovich's kinetic models were used to fit the data gotten from experimental findings. The three models fitted the experimental data suitably, with hyperbolic kinetic model giving the best fit (R2=0.93288, RMS=0.12133, and SD=0.02715) followed by Elovich's model kinetic model (R2=0.92172, RMS=0.205329, and SD=0.039349) and (R2=0.92968, RMS=0.66867, and SD=0.542885) in that order. Thermodynamic parameters ∆H and ∆S for ASA seed oil extraction were evaluated at temperature of 318 K. The enthalpy values for the five particle sizes used were 19.35, 22.24, 26.08, 29.57 and 49.98 KJ/mol and the Entropy 0.08, 0.09 0.10 0.11 and 0.17 KJ/mol respectively. These positives values for the enthalpy and entropy change shows that the extraction is endothermic and irreversible in nature. The Gibbs free energy change (∆G) for the extraction was found to be below zero showing that the extraction was a spontaneous process. Using ANOVA and Tukey's post hoc HSD analyses, extraction time variation was found to significantly affect oil yield. Particle size and extraction temperature variations were statistically insignificant.

Keywords

• Oil extraction
• Kinetic models
• Thermodynamics
• Particle size
• Yield
• Chrysophyllum albidum