Response surface methodology optimization of oil extraction from oil palm meal (OPM) with hydrous ethanol and its pilot-scale application with recirculation of extraction solvent

Abstract

In the small-scale dry oil extraction from palm fruit used by palm oil mills, mixed crude palm oil (MCPO) is extracted using a single screw press. The oil palm meal (OPM) by-product can be used as alternative feed for ruminants. Three parameters in further solvent extraction of oil are the ethanol-to-dried oil palm meal (DOPM) ratio (4.9–30.1 g.g-1), the extraction time (0.2–18.8 min), and the speed of stirrer (48–552 rpm). These parameters were optimized to for maximum oil yield by response surface methodology (RSM) while employing hydrous ethanol as the solvent. In our laboratory-scale oil extraction, the maximal experimental yield was 10.27 wt.% under the recommend condition: 20.1 g.g-1 ethanol-to-DOPM ratio, 11 min extraction time, and 300 rpm speed of stirrer. Moreover, prototype-scale oil extraction was tested with recirculated miscella for effects of the number of cycles on oil extraction from fresh DOPM. The results showed approximately 17.4 wt.% oil yield from 5000 g DOPM at the conditions recommended based on laboratory-scale experiments. In this study, recirculated miscella was used to extract oil from fresh DOPM. The first four cycles of oil extraction were almost as efficient as with fresh ethanol. Moreover, the protein content in the defatted oil palm meal (DFOPM) improved with oil extraction, because residual oil in DOPM was removed. The DFOPM should have less rancidity and longer shelf-life than DOPM.