Oil produced from Ghana Shea Nut crop for prospective industrial applications

Abstract

Though little research has been done, shea nut oil (Shea Butter), is a promising shea product with great potential for use in industrial shea product manufacture. To assess the oil obtained from the shea nuts for personal, commercial, and industrial use, this study focuses on the extraction process, the optimal solvent for extraction, thermodynamics and kinetic studies, and characterization of the oil. Using different solvents as well as extraction temperatures and times, the oil was extracted using the solvent extraction method. Moreover, models of thermodynamics and kinetics were used in examining the Shea nut oil extraction at different durations and temperatures. At the highest temperature of 333 K (at 130min), the highest oil yields of 70.2 % and 59.9 % for n-hexane and petroleum ether, respectively, were obtained, following first order kinetics. For both petroleum ether and n-hexane, the regression coefficient (R2) was 1. For the extraction with n-hexane and petroleum ether, the mass transfer coefficient (Km), activation energy (Ea), entropy change (ΔS), enthalpy change (ΔH), and Gibb's free energy (ΔG) were, respectively, (0.0098 ± 0.0061 and 0.0123 ± 0.0084) min−1, 74.59 kJ mol−1 and 88.65 kJ mol−1, (−236.15 ± 0.16 and −235.63 ± 0.17) J/mol K, (71.88 ± 0.06 and 85.94 ± 0.06) kJ/mol, and (148.75 ± 1.52 and 162.46 ± 1.52) kJ/mol. These values favor an irreversible, forward, endothermic, and spontaneous process. Gas chromatography analysis was used to identify the principal fatty acids in the oil, which include stearic acid (52 %), oleic acid (30 %), and linoleic acid (3 %), as well as various minor fatty acids. The oil's potential bonds and functional groups were identified using Fourier Transform Infrared analysis, and the physicochemical parameters such as the iodine value, peroxide value, acid and free fatty acid values were found to be within acceptable ranges for use in domestic, commercial, and industrial settings.