Quantitative and qualitative characterization of mango kernel seed oil extracted using supercritical CO2 and solvent extraction techniques

Characterization of mango kernel seed oil extracted using supercritical CO2 (SC-CO2) and conventional solvent (hexane, petroleum ether, ethanol and acetone) extraction techniques was carried out using differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), Gas chromatography mass spectroscopy (GC-MS) and fluorescence microscope. The extractor and separator temperatures of the SC-CO2 were 60 and 50 degrees C respectively while the pressure was varied from 35 to 40 MPa. Solvent extractions were maintained at the boiling points of the various solvents. The results indicated that solvent extraction had higher yields (8.02-19.88%) while SC-CO2 had a lower yield (2.5-3.6 %); the yield of conventional solvent extraction increased with decreasing particle sizes. Ethanol extracted oil had lowest enthalpies of endothermic reaction (1.17-2.74 J/g); while other solvents were between 42.54 and 45.64 J/g with SC-CO2 having 37.40 J/g. The melting points for ethanol extracted oil were 7.34 and 35.20 degrees C; other solvents ranged between 13.39 and 15.15 degrees C while, SC-CO2 was 35.05 degrees C. SC-CO2 extracted oil had no crystallization parameter, while conventional solvent extracted oil with the exception of ethanol were between -33.23 and -33.97 J/g. The FTIR showed that CH3, CH2 and COH were the predominant functional groups in hexane, petroleum ether, acetone and SC-CO2-extracted oil; ethanol extracted oil had -OH and CH2. The extracted oil using solvent extraction technique was higher in unsaturated fatty acid (UFA) with the exception of acetone extracted oil. SC-CO2 extracted oil had higher saturated fatty acid (SFA) content (47.01%). The predominant UFA and SFA were oleic acid stearic acid.