Keywords: microemulsion-based extraction, palm kernel, peanut, Brij 30, solvent extraction

Abstract

Soxhlet extraction method using hexane is widely used for vegetable oil extraction. This method is very efficient but the presence of hexane residue in the extract is not favorable. However, the difficulty in complete removal of this residue in the extract is a problem. Thus, this study introduces microemulsion-based extraction of palm kernel oil and peanut oil using polyoxyethylene (4) lauryl ether nonionic surfactant or the commercial name Brij 30 as an alternative method to replace solvent extraction. Parameters that were studied to find the optimum oil extraction conditions are weight of sample, surfactant concentration, and contact time. Once the optimum conditions were obtained, solvent extraction was done for comparison. The oil collected from both extractions was compared based on their extraction efficiencies and Fourier Transform Infrared Spectroscopy (FTIR) characterization. Dried and ground palm kernel and peanut (0.2-0.5 mm) were shaken with surfactant on rotary shaker at 150 rpm for every parameter. This enables the oil to be collected because it is liberated from the samples as a separate phase from the aqueous phase. Optimum oil extraction of 59.2 % and 87.15 % was achieved at weight of sample of 1.0 g, 30 minutes extraction time at 150 rpm and 0.015 M surfactant concentration for palm kernel and peanut respectively. Percentage of palm kernel and peanut oil extraction using microemulsion-based extraction are 59.2 % and 87.157 % respectively which are lower compared to solvent extraction; 88.5 % and 91.37 % respectively. FTIR characterization on both methods shows not much difference due to the same source of origin. The formation of oil was proven by ester formation that was detected at 1743 cm-1. Although microemulsion-based extraction efficiency is lower than extraction using solvent, the process requires shorter time than solvent-based extraction method. Furthermore, the usage of surfactant especially the polyoxyethylene-based group is environmentally friendly compared to solvent such as hexane.