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INTERDISCIPLINARY JOURNAL OF CONTEMPORARY RESEARCH IN BUSINESS
oil is dissolved in a solvent, to separate it from the insoluble meal that is primarily
composed of protein and carbohydrate.
Various liquids has been in use as solvents for commercial oil extraction by the vegetable
oil industries and others has been proposed based upon encouraging laboratory results.
However, mixture of hexane rich in n-hexane, have been the solvent of choice by the oil
seed processing industries for the past 50years. Due to the toxicological, environmental
and economic reasons, other solvents have been proposed as an alternative to hexane.
Palm kernels are usually prepared for solvent extraction by cracking, heating and flaking
or by conditioning, screw-pressing, grinding and flaking.
In a (continuous) solvent extraction process, the seeds are contacted with a solvent,
generally hexane. The oil contained in the seeds is dissolved in the solvent after which
solvent and solids are separated. The solvent/oil mixture (usually 20-33 wt% oil)
(Technology and solvents for extracting oilseeds and nonpetroleum oils; Wan, P. J.;
Wakelyn, P. J., Eds.; AOCS Press: Champaign,2004) is sent to the solvent recovery
operation, where solvent is removed by evaporation. The residual cake is sent to a desolventiser
/ toaster, which also removes the solvent by evaporation. Both oil and solids
therefore undergo a heat treatment, which is detrimental for the oil and cake quality. The
co-extraction of undesired components further reduces the quality of the oil. However,
with this method it is possible to recover almost all of the oil from the seeds. Generally,
this method is used in the high(est) capacity plants. To further improve the efficiency of
the process, the extraction can be preceded by a pre-pressing step. Here part of the oil is
recovered by a screw press, which reduces the size of the extractor and improves the
permeability of the solids.
Figure 4: Hexane solvent extraction flow diagram.
Source; Wan, P. J.; Wakelyn, P. J., Eds.; (2004)
COPY RIGHT © 2011 Institute of Interdisciplinary Business Research 68
JANUARY 2011
VOL 2, NO 9