Extraction of palm kernel oil rich in bioactive compounds from palm kernel employing supercritical carbon dioxide

This study aimed to investigate the extraction of palm kernel oil (PKO) from palm kernels using supercritical carbon dioxide (SC-CO 2 ). SC-CO 2 extraction was performed at pressures of 15 – 25 MPa and temperatures of 40 – 60 ° C. The effects of operating conditions on the yield were determined, and the optimum operating conditions were identified using the response surface methodology-central composite design (RSM-CCD). The extract obtained under the optimal conditions, which resulted in the highest extraction yield, was analyzed for its fatty acid composition and antibacterial activity. The residue of palm kernel was analyzed using FTIR and SEM to characterize its functional groups and morphology. The results showed that increasing the CO 2 flow rate and palm kernel weight while maintaining a constant Q/F ratio of 0.4 mL/min·g primarily accelerated the extraction process, while only minor differences in the final extraction yield (approximately 0.01 g/g) were observed, with similar extraction profiles. SC-CO 2 extraction resulted in a higher yield (0.53 g/g) than Soxhlet extraction (0.49 g/g). The extraction yield increased with the increasing pressure and decreased with the increasing temperature. RSM-CCD optimization results indicated that the optimum operating condition for SC-CO 2 extraction was achieved at a pressure of 24.184 MPa and temperature of 40.953 °C, which resulted in 0.532 g PKO/g palm kernel. SEM images revealed increased surface disruption in the extracted palm kernel residues, while FTIR spectra indicated reduced intensities of lipid-associated bands, supporting the partial removal of oil components from the palm kernel matrix. The PKO extract contained 41.89% and 40.24% lauric acid for SC CO 2 and Soxhlet extraction, respectively, and exhibited antibacterial activity against both Staphylococcus aureus and Escherichia coli , with greater activity toward gram-positive bacteria. This study demonstrates that SC-CO 2 extraction is more effective and sustainable alternative to conventional extraction for PKO recovery. Furthermore, the preservation of extraction performance while maintaining a constant solvent flowrate-to-feed (Q/F) ratio, one of the primary scale-up criteria for extraction processes, suggests its potential applicability for future industrial-scale implementation.