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INTERDISCIPLINARY JOURNAL OF CONTEMPORARY RESEARCH IN BUSINESS
time. For such processes, it is possible to achieve oil yields in excess of 95% with a
solvent recovery of over 95%. In the past, the main concern of this process has been the
safety implications surrounding the use of hexane. This prompted attempts to develop
processes based on the use of aqueous extraction media which were unsuccessful mainly
due to low oil yields. The process called water-flotation has been used for extracting
coconut and palm oil. It involves heating oily material, grinding with or without water,
and boiling with water to liberate the oil. The oil, which appears on the surface, is
collected and heated to remove moisture. Oil extraction yields of around 50 percent are
generally considered to be satisfactory for traditional non-commercial processes. This
process can be used to extract oil as well as high quality proteins. In order to improve oil
and protein extraction yields and to undertake extraction under milder processing
conditions, some enzymes or surfactants are added to the extraction medium.
13.1 ADVANTAGES AQUEOUS EXTRACTION
� Simultaneous production of edible oil and protein isolate or concentration in the same
process.
� Lower protein damage during extraction.
� Improved process safety due to the lower risk of fire and explosion.
� Aqueous extraction processes may be more cost effective since the solvent recovery
step is eliminated.
� An environmentally cleaner alternative technology for oil extraction.
13.2 LIMTITATIONS OF AQUEOUS EXTRACTION
� Lower efficiency of oil extraction.
� De-emulsification requirements to recover oil when emulsions are formed.
� Treatment of the resulting aqueous effluent.
� Enzyme and surfactant costs.
� Finely ground seeds, which cause dusting, may lead to an explosion if the processing
area is not ventilated well.
14. OIL REFINING
Vegetable oil refining is a necessary process required to convert a crude that is
undesirable for human consumption into a wholesome nutritious food oil. The oil
removed or extracted from an oil seed by mechanical or solvent extraction has many
undesirable components. The components ranges from merely giving bad taste to being
harmful for human consumption. The refining process remove non oil components from
the oil while maximizing the oil yield at a minimum cost and maximum quality. The
primary non-oil component removed are; the free fatty acid, phospholipids(gums),
tocopherols, sterols, pigments and other minor impurities. The removal of these
impurities gives the oil properties that are important to consumer such as taste, light
colour, long shelf life and goo ked odour. The compositions of crude palm kernel oil is
as shown in the table below.
COPY RIGHT © 2011 Institute of Interdisciplinary Business Research 73
JANUARY 2011
VOL 2, NO 9