Understanding
Oil Extraction Methods:
Expeller pressed vs solvent extracted oils
Expeller pressing is the method of extracting oil with a mechanical press
rather than utilizing a chemical extraction process. There are no solvent
(chemical) residues in oil that has been expeller pressed resulting in
a cleaner more pure oil, higher in natural colors and flavors. The process
of extraction is the critical quality difference between oils often found
in the natural foods marketplace as opposed to mass market or supermarket
brands.
An expeller press is a screw type machine, which presses oil seeds through
a caged barrel-like cavity. This machine uses friction and continuous
pressure from the screw drives to move and compress the seed material.
The oil seeps through small openings that do not allow seed fiber solids
to pass through. Afterward, the pressed seeds are formed into a hardened
cake, which is removed from the machine. Pressure involved in expeller
pressing creates heat in the range of 140-210º F (60-99º C).
Solvent extraction is achieved through the grinding of seed. The ground
seed or cake is then purged or washed with a petroleum distillate (the
most common chemical used is hexane) which releases the oil in the seed.
The solvent is then “flashed off” by heating the oil in a
sealed chamber. The oil/solvent blend is next heated to 212º F (100º
C) to distill off the solvent. This process theoretically leaves virtually
no detectable levels of solvent in the oil if the proper techniques have
been applied. However, microscopic portions (up to 25 parts per million)
of hexane can remain in the meal and the finished oil. Commercial oil
companies claim hexane is completely removed in the recovery phase of
the extraction cycle. However, this cannot be guaranteed as manufacturing
practices and quality control standards vary enormously from processor
to processor.
The majority of vegetable oils sold as bottled product or food ingredient
in the mass market or conventional food industry are solvent extracted
oils. Mass market oils, however, are not required to be labeled as solvent
extracted. The main reason for using solvent extraction is largely economic
as the greater efficiencies of solvent extraction maximizes yields and
profits. This is why solvent extraction has evolved into the most common
form of oil removal – it delivers the least expensive and subsequently
the lowest quality vegetable oils.
Spectrum Ingredients is the leader in providing the highest quality
expeller oils to manufacturers of food and health and beauty aid products.
We are committed to supplying our customers with premium pure oils.
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