Note: Descriptions are shown in the official language in which they were submitted.
WO 94/00541 ~~~~~~~ PCT/US93/05599
EXTRACTION OF OILS FROM GRAIN MATERIALS
AND GRAIN-BASED FOOD PRODUCTS
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to a process for the extraction of oils from grain
materials such as
rice bran, wheat mill feed, Canola~, rapeseed, amaranth and similar grains.
The process not only
provides a method of oil extraction, but provides for the separation of
saturated from unsaturated
oils. A specially designed apparatus is used to achieve this separation. Use
of the process not only
provides the extracted oil, but also enables production of a number of grain
products having low
residual oil contents, which products have particularly desirable food and
feed characteristics.
The process for oil extraction applicable grain materials can also be applied
to crushed or
flaked vegetable matter and to grain-based food products which are somewhat
porous, such as
chips, noodles and crackers.
2. Background of the Invention
It is known that the best and easiest oilseed to process is soy bean. Canola~
and rapeseed
have also been processed on the kind of equipment used to process soy bean;
however, they have
been ground, cooked, and rolled into flakes to provide an extractable bed.
Generally Canola~
flakes can be run only at a much slower rate than soy beans. The resultant
rapeseed and Canola~
residual material after oil removal, called "Mart", cannot readily be used as
meals for animal
feeding due to the presence of trypsin inhibitors, high euric acid and high
glucosinolates.
The process and apparatus of the present invention can be used to process oil
seeds such
as soy bean and safflower; however, the process was designed particularly for
obtaining oil from
grain materials such as rice bran, wheat mill feed, Canola~, rapeseed in
general, and amaranth (as
will as similar grains). These grain materials do not have as high an oil
content as soy bean and
safflower and have not been economically competitive as an oil source prior to
the present process.
Typically, oil seeds contain from about 15 percent to about 40 percent by
weight oil. Grains of
the kind described above contain only from about 4 percent to about 20 percent
by weight oil, and
prior to the method of the present invention, processing of grain materials
having this low oil
content was not competitive with processing of oil seeds. The present oil
extraction method makes
possible not only the extraction of oil from grain materials, but further
extraction of additional oils
from crushed or flaked vegetable materials previously oil extracted using a
less efficient method
of extraction, such as crushed peanuts or olives. The present oil extraction
method also enables
additional oil extraction from grain-based products such as chips, noodles and
crackers, by way of
example and not limitation.
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WO 94/00541 PCT/US93/05599
In addition to having a lower oil content, the grains frequently require
special processing
in preparation for oil removal, and when a grain oil source such as rice bran
is used, the rice bran
itself has a limited shelf life before the oils begin to degrade, due to
particularly active enzymes
present in the bran. Thus, there are particular handling requirements and
processing requirements
necessary to enable the use of such grain materials as a source for edible
oils.
Most oil seeds are extracted by soaking them in liquid Hexane. The hexane and
oil
mixture, is called "Miscella" . The oil is then separated from the miscella by
a process of
distillation, and the hexane solvent is recovered for recycle use in the
separation process. The
Marc which remains after removal of the oil from the seeds is generally a
powder and contains
substantial amounts, up to about 40 percent, of hexane. The Marc is then
"dried" to recover the
residual hexane. Recovery of the hexane from the Miscella and from the Marc
are both energy
intensive processes and require extensive capital equipment.
As previously discussed, Canola~ and rapeseed in general have been processed
on soy bean
equipment; they have been ground, cooked and rolled into flakes prior to oil
extraction. Even then,
the process rate in oil seed processing equipment was marginally cost
effective compared with soy
bean. Other potential grain material sources of oil include wheat mill feed,
amaranth, and rice
bran; for example. Wheat mill feed is the material removed from wheat during
milling. Twenty
percent or more of all the world's wheat ends up as mill feed. Most of this
goes into pet food and
animal feed. Amaranth, another potential source of oil, known in the midwest
as "pig weed",
grows wild. The amaranth cultivars, i.e. the plants and hybrids are available
to anyone through
the U.S.D.A. Wheat mill feed and amaranth can both be extruded into an
extractable pellet
because they contain sufficient amounts of starch and sugars. The pellets can
be processed on
standard soy bean equipment, but the hexane solvent typically used for
extraction also extracts large
quantities of green chlorophyll so that the oil is difficult to refine as well
as being dark green,
almost black in color. Rice bran requires a particularly specialized process.
The rice bran cannot
easily be flaked or made into an extrudable pellet because of lack of starch
and the presence of
sucrose. Rice bran can be extruded if corn starch is added, but the sucrose
can caramelize if heated
in the presence of air, giving a dark hue to the oil product. Rice bran can be
extracted with hexane
using an extractor of the type used to process soy beans, but this process is
comparatively slow,
energy intensive and expensive when compared to soy beans.
There are numerous possibilities for removing oil from vegetable matter and,
in particular,
from grains. Each has advantages and disadvantages. The present invention
provides a very
economical method of extracting oil from materials having a low oil content,
such as grains, pre-
extracted vegetable matter and grain-based food products. Further, the present
invention provides
a method of separating the extracted oil into at least two fractions, one
fraction which contains
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WO 94/00541 PCT/US93/05599
principally saturated components and at least one other which contains
principally unsaturated
components. The separation achieved by the method is unexpected in view of the
known art and
provides a highly desirable oil product, which is low in saturated components.
SUMMARY OF THE INVENT10N
In accordance with the present invention, edible oils can be extracted from
materials having
an oil content of 20 % by weight or less in a manner which provides low
temperature, low-energy-
consumption processing conditions. The materials having an oil content of 20 %
or less include
grain materials, for example, rice bran, wheat mill feed, Canola~ and rapeseed
in general, and
amaranth; pre-extracted vegetable matter such as crushed peanuts and olives;
and grain-based food
products such as chips, crackers and noodles, where the grain product is in a
flaked or thin strip
form. The method of the present invention can also be applied to grain seeds,
vegetable matter and
grain-based food products containing more than 20% by weight oil if desired.
The method can provide for the separation of an oil/solvent composition into a
principally
saturated oil fraction and a principally unsaturated oil fraction. In
addition, the resultant extracted
grain product is stabilized against degradation while offering valuable food
and feed potential.
Granular and seed materials from which oil is to be extracted can be prepared
for oil
extraction by mechanical size reduction using methods known in the art. Grain
materials having
a relatively high porosity (in the range of 50 % or more internal porosity)
typically will not have
to be reduced in size prior to oil extraction.
As an alternative to size reduction, feedstock to the oil extraction process
can be prepared
(and stabilized from degradation where applicable) by the following method: a)
moisture content
of the material is increased, as necessary, typically to a moisture content
ranging from about 6
percent to about 14 percent; b) the material is then heated to a temperature
ranging from about
115 °F to about 215 °F; and, c) the surface of the heated
material is exposed to a vacuum of about
25 in. Hg absolute or less, preferably less than about 10 in. Hg absolute, and
most preferably less
than about 4 in. Hg absolute. This treatment of the granular or seed material
causes surface
rupture due to expanding moisture, providing the necessary and porosity to
permit solvent
extraction of the contained oils. Further, despite this increase in porosity,
applicants have found
this treatment of the grain material makes it possible to store such material
(even that in which the
oil typically degrades rapidly) for extended periods of time, up to several
months, without
significant change in the overall composition of the oil components within the
grain material.
The oils are extracted from prepared grain materials, vegetable matter or
grain-based
food products using a vaporized solvent for the oils contained therein, which
vaporized solvent is
not a solvent for the protein in the grain material, vegetable matter or grain-
based food product.
Applicants have discovered that there is an advantage in using particular
vaporized solvents
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WO 94/00541 ~~3~3~~ PCT/US93/05599
which are capable of forming a weak :' chemical bond or association with the
oil to be extracted.
Such solvents permit more rapid oil extraction under milder extraction
conditions. This
weak bonding or association permits the solvent molecule and the oil molecule
to act as one
unit for purposes of removing the oil from the grain material, vegetable
matter or grain-
based food product; however, since the bond or association is weak, the
solvent can be
subsequently separated from the oil using distillation techniques which make
sufficient energy
available for breaking the weak bond or association. The oil is extracted by
contacting the grain
material, vegetable matter or grain-based food product with the vaporized
solvent, using a relatively
low temperature, ranging from about 100°F to about 190°F under a
partial vacuum ranging from
about atmospheric pressure to about 0.1 in. Hg absolute, depending on the
location of the grain
material within the oil-extraction apparatus.
The resulting oil/solvent composition can then be processed through a
separation means,
whereby a saturated oil/solvent fraction is separated from an unsaturated
oil/solvent fraction. Each
oil/solvent fraction can subsequently be distilled to provide separation of
the oil from the solvent.
The preferred solvent for oil extraction by the vaporized solvent process is
an acetate such
as, for example, methyl acetate or ethyl acetate. Other solvents such as
alcohols or organic
solvents which are polar in nature and capable of hydrogen bonding or forming
associations can
also be used. When the extracted oil or Marc is to be used for food or feed,
the preferred solvents
are food grade solvents, such as ethyl acetate, methanol, ethanol, isopropyl
alcohol, hexyl alcohol,
heptyl alcohol, or dectyl alcohol, either alone or in various combinations.
The prepared grain material, vegetable matter or the grain-based food product
is contacted
with an extraction solvent which is in vaporous form. A feedstock which is
relatively fracture
resistant can be processed using counter current flow of the material to be
extracted relative to the
extraction solvent vapor. For example, a grain material can be propelled
downward in a manner
which takes advantage of gravity flow, while the extraction solvent rises
upward through the grain
material and is collected in the upper portion of the contacting apparatus. In
the alternative, the
grain material or a more fragile grain-based food product can be moved along a
perforated
conveyor belt while the vaporized extraction solvent is passed through the
grain material. For
example, the vaporized solvent can pass from a source beneath the perforated
conveyor belt, up
thorough the grain material or grain-based food product and toward a partial
vacuum source located
above the grain material. The partial vacuum can be created using a flue or
using a flue in
combination with a condenser. Typically a partial vacuum is used in the upper
portion of both
kinds of the extraction apparatus described above, to direct a volatile
oil/solvent composition to a
collection area at that location.
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WO 94/00541 ~~~~~ PCT/US93/05599
A portion of the extracted oil and solvent typically remains on the surface of
the grain
material or grain-based food product. There are numerous techniques which can
be used to remove
this oil/solvent composition from the grain material surface, such as
centrifugation, permitting the
grain material or grain-based food product to stand so that gravity separation
occurs, suctioning the
composition from the grain material surface using a vacuum, and combinations
of such techniques.
The contacting of a prepared grain material, a flaked vegetable matter, or a
grain-based
food product with a volatilized extraction solvent is carried out at a
volumetric ratio of solvent to
grain material ranging from about 3 : 1 to about 10 : 1, and preferably at a
volumetric ratio of
solvent to grain material ranging from about 6 : 1 to about 8 : 1. The
contacting is carried out
in a manner such that the amount of solvent utilized to extract the oil from
the grain material ranges
from about 0.7 : 1 to about 5 : 1 on a weight of solvent : weight of grain
material basis. The
extracted grain material, flaked vegetable matter or grain-based food product
is processed to
remove residual solvent and or solvent/oil component using techniques known in
the art such as
rotary drum drying and vacuum assisted solvent removal techniques. The
extracted grain-based
food product typically is processed by exposure to vacuum alone or combined
with heat, depending
on the ftagility of the product. The various oil/solvent compositions
collected may be stored prior
to further processing, or may be fed directly to an apparatus for separating
heavier, principally
higher molecular weight unsaturated oils from lighter, principally lower
molecular weight saturated
oils.
The oil/solvent composition is separated into heavier and lighter oils by
processing through
a specially developed separation apparatus. Typically the oil/solvent
composition ranges from about
10 percent oil with 90 percent solvent to about 40 percent oil with 60 percent
solvent, on a weight
to weight basis. The preferred apparatus for separation is a chamber having at
least two volumetric
areas comprising packing and having a relatively open (unobstructed)
volumetric area between
them. A partial vacuum is typically applied principally to the upper packed
volumetric area. The
oil/solvent product is fed, preferably in a periodic or pulsed manner, into
the relatively open
volumetric area between the packed volumetric areas. A heavier oil/solvent
fraction, comprising
principally unsaturated oils having from about 16 to about 24 carbon atoms and
particularly having
from about 18 to about 24 carbon atoms, is collected in the lower portion of
the separation
apparatus, while a lighter oil/solvent fraction, comprising principally
saturated oils having from
about 4 to about 16 carbon atoms, is collected in the upper portion of the
separation apparatus.
Typically, the average residence time of oil/solvent components in the upper
packed volumetric
area is less than about 5 minutes and the average residence time of
oil/solvent components in the
lower packed volumetric area is less than about 2 minutes.
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WO 94/00541 PCT/US93/05599
Both the heavier oil/solvent fraction and the lighter oil/solvent fraction are
further processed
to separate the oil from the solvent, providing at least two oil products and
solvent which can be
recycled within the process. Typically the separation of oil from solvent is
accomplished using
distillation techniques known in the art.
The apparatus for stabilizing the oil content of rice bran and for preparing
grain materials
for oil extraction by rupture of the surface and opening of conduits within
the grain material
comprises the following elements:
a) a means for increasing the moisture content of the grain material feed
stock to at least
6% by weight moisture. Typically the grain material is contacted with water at
room temperature
and allowed to stand until the water is absorbed and reaches an equilibrium
within the grain
material. Preferably the moisture content of the grain material is increased
so that it ranges
between about 12 % to about 16 % by weight moisture;
b) a means for heating the grain material to a temperature ranging from about
100 °F to
about 215 °F, depending on the amount of vacuum subsequently applied.
Typical ly the heat is
applied using steam to prevent moisture loss from the grain material.
c) a means for applying vacuum to the grain material, whereby the moisture in
the grain
material expands, to rupture the surface of and create pathways within the
grain material which
make the oil contained in the grain material accessible to the extraction
solvent used to extract the
oil. The expanded, porous grain material is then cooled, and can be stored
until oil extraction is
carried out. The porous grain material can be stored for time periods ranging
from a few weeks
to a few months depending on storage temperature and humidity conditions.
Although it is not necessary to prepare all grain materials for extraction
using the above-
described method of increasing porosity, this preparation is particularly
helpful in the extraction
of oil from rapeseed and amaranth.
The apparatus used for separation of an extracted oil/solvent composition into
a principally
unsaturated oil/solvent fraction and a principally saturated oil/solvent
fraction comprises the
following:
A mufti-chambered process vessel having a feed inlet chamber which is a
relatively
open, unpacked volumetric space and having at least two additional chambers
attached to
the feed inlet chamber, which additional chambers contain packing of the kind
used in the
chemical industry in separations processes. The feed inlet chamber may contain
baffles or
other means for directing entering feed (extracted oil/solvent composition)
within the inlet
chamber toward attached packed second and third chambers. In addition, the
apparatus
includes at least one means for applying vacuum to at least one of the
chambers of the
process vessel.
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WO 94/00541 PCT/US93/05599
Preferably the process vessel chamber is constructed in the manner of a packed
separation
column, having a partial vacuum applied to the upper portion of the column, so
that gravity can
be used to pull heavier molecules toward the bottom of the column while
lighter molecules tend
to rise toward the upper portion of the column. In a preferred embodiment, the
oil/solvent
~ composition, in the form of a vapor, enters the feed inlet (first) chamber
through at least one feed
stream supply means located within the inlet chamber. In the most preferred
embodiment, the feed
stream supply means provides a periodic or pulsed feed stream. One means is
provided for
removing the processed lighter oil/solvent product from a location at or above
a packed (second)
chamber, and a second means is provided for removing the processed heavier
oil/solvent product
from a location at or below a packed (third) chamber of the separation
apparatus vessel. Typically
at least one of the product streams will be a vapor, and means for condensing
such vapors is
provided. The vaporous product streams withdrawn from the separation apparatus
may flow
directly to a distillation apparatus for separation of the oil/solvent
fraction into an oil product and
recycle solvent. Vaporous or condensed product can be withdrawn from any
location within the
separation apparatus vessel and recycled to any other location within the
vessel, to provide the
desired product streams. The number of packed chambers and relatively open
chambers can be
tailored to the desired product. Several separation apparatus can be used in
series, or in parallel.
Not only are edible oils produced from the process of the present invention,
but numerous
products comprising the Marc, residual grain material after oil extraction,
are of special interest
as valuable food and feed products.
The extracted oils generated from rice bran typically include about 20 % by
weight light
oils, typically saturated fats and waxes, and about 80 % by weight heavier
oils, typically
unsaturated fats and fatty acids. These light and heavier oil components can
be separated by the
process of the present invention into a principally unsaturated fraction
comprising linoleic, linolenic
and liconsenic acids and a principally saturated fraction including oleic,
stearic and palmitic acids.
It is particularly important that the principally unsaturated oil fraction
obtained from amaranth and
rice bran also contains Vitamin E of the rare alpha type. This type of vitamin
E is linked to
lowering human cholesterol levels.
A blend of extracted amaranth Marc with extracted, stabilized rice bran Marc
provides a
specific outstanding feed product which has the amino acid equivalent of soy
bean meal. The blend
typically ranges from about 80 : 20 to about 60 : 40, rice bran Marc :
amaranth Marc, on a weight
to weight basis. The blend of rice bran Marc with amaranth Marc typically has
a total oil content
ranging from about 0.5 percent to about 10 percent by weight oil. Additives
can be combined with
the Marc blend if desired for a particular application. A particularly
preferred animal and poultry
feed product obtainable using the extraction process of the present invention
is a blend of the
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WO 94/00541 PCT/US93/05599
stabilized rice bran Marc with whole amaranth. The preferred blend comprises a
ratio of rice bran
Marc to whole amaranth ranging from about 75 : 25 to about 60 : 40, on a
weight to weight basis.
The blend of rice bran Marc with whole amaranth typically has a total oil
content ranging from
about 2 percent to about 14 percent by weight oil. As previously described,
other additives can
be combined with the blend if desired.
Another outstanding feed product which can be generated from Marc obtained
using the
process of the present invention comprises Canola~ or rapeseed Marc and
another component
selected from the group consisting of rice bran Marc, amaranth Marc, whole
amaranth, or mixtures
thereof, wherein the weight to weight ratio of Canola~ or rapeseed Marc to the
component selected
ranges from about 30 : 70 to about 50 : 50. This feed product typically has a
total oil content
ranging from about 0.05 percent by weight to about 14 percent by weight oil.
The grain-based food products such as crackers, noodles and chips which are
processed
using the oil extraction process of the present invention contain
significantly less oil (typically 2-10
by weight than grain-based food products currently marketed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 shows a schematic of a combination of process steps which comprise a
preferred
embodiment of the method of the present invention. This embodiment includes
step 110:
preparation of the grain material for oil extraction (increasing porosity of
the grain material and
in some instances stabilizing the oil content of the grain material); step
112, solvent extraction of
the oils from the grain material; step 118, separation of the extracted
oil/solvent composition into
principally saturated oil/solvent and principally unsaturated oil/solvent
fractions; further separation
of fatty acids from both the principally unsaturated oil/solvent fraction and
the principally saturated
oil/solvent fraction as shown in steps 122 and 120, respectively; and, step
114, separation of
solvent from the extracted grain material and from the fatty acid/solvent
component.
FIGURE 2 shows a schematic of a preferred embodiment of the method for
preparation of
grain material, whereby increased porosity of the grain material is obtained
using the moisture
content of the grain material under a reduced pressure.
FIGURE 3 shows a schematic of a preferred apparatus which can be used for
preparation
of a grain material prior to solvent extraction, and to stabilize the grain
material for storage.
FIGURES 4A and 4B show schematics of a preferred apparatus for extraction of
oil from
grain materials or grain-based food products using an extraction solvent in
vapor form. FIGURE
4A shows an apparatus comprising perforated conveyor on which the grain
material or grain
product travels while solvent vapor passes through the grain material or grain-
based food product.
FIGURE 4B shows as apparatus which can be a continuation of the apparatus
shown in FIG. 4A
or which can be an auxiliary apparatus. In the FIG. 4B apparatus, residual
oil/solvent compositions
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WO 94/00541 ' ~~''PCT/US93/05599
are removed from the surface of the grain material or grain-based food product
using a partial
vacuum in combination with gravity flow.
FIGURE 5 shows a schematic of a preferred embodiment of the method for
separation of
an extracted oil/solvent composition into a principally saturated oil/solvent
fraction and a principally
unsaturated oil/solvent fraction. Auxiliary separation of the solvent (for
recycle in the oil extraction
process) from these components is also illustrated.
FIGURES 6A and 6B show schematics of preferred embodiments of an apparatus for
separation of the extracted oil/solvent composition into particular
oil/solvent fractions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In accordance with the present invention, a method is provided for obtaining
particular oil
compositions from grain materials including, for example, rice bran, wheat
mill feed, Canola~,
rapeseed, amaranth, and similar grains. Further, the method provides for
separating the extracted
oil/solvent composition obtained from the grain materials into principally
saturated and principally
unsaturated oil fractions. Particular apparatus are described for use in
preparation of the grain
material for extraction of the oil from the grain material, and for separation
of the extracted
oil/solvent composition into principally saturated and principally unsaturated
oil fractions. In
addition to processing of the extracted oil, the grain material residual after
oil extraction (Marc)
has been further processed and blended into valuable feed and food products,
which are also
described.
The process for oil extraction applicable to grain materials can also be
applied to crushed
or flaked vegetable matter and to grain-based food products which are somewhat
porous, such as
chips, noodles and crackers.
FIG. 1 shows a schematic of a combination of process steps which can be used
to obtain
particular components from grain materials such as wheat and rice brans and
seeds. With reference
to FIG. l, the grain material is made more porous (and the oil stabilized from
degradation in some
circumstances) in step 110. This optional step can be used to prepare the
grain material for more
efficient stripping of the oil. The porous grain material is then contacted
with solvent vapors in
a solvent extraction step 112, whereby the oil is removed from the grain
material. The stripped
grain material, having the oil extracted, Marc, can then be treated in step
114 to remove the
residual solvent, which can be recycled into the stripping operation. The Marc
can be further
processed in step 116 into a given food or feed product.
The extracted oil/solvent composition can be distilled to provide an oil
product and solvent
which can be recycled to solvent extraction step 112. However, preferably the
extracted oil/solvent
composition is processed in step 118 to separate the composition into a
principally saturated
oil/solvent fraction and a principally unsaturated oil/solvent fraction. The
principally saturated
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WO 94/00541 PCT/US93/05599
oil/solvent fraction, which comprises saturated oils, waxes and fatty acids is
separated in step 120
to produce a principally saturated oils and waxes product and a fatty
acid/solvent component; the
latter component can be subsequently separated in step 126 into a fatty acid
product and solvent
for recycle into solvent extraction step 112 or into separation step 118. The
principally unsaturated
oil/solvent fraction, which comprises unsaturated oils and fatty acids, is
processed in step 122
(typically distilled) to separate the fatty acids and solvent from the
unsaturated oils, providing a
principally unsaturated oil product. The fatty acids can be subsequently
separated in step 124 from
the solvent, providing a fatty acid product and solvent for recycle into
solvent extraction step 112
or into separation step 118.
When a grain material such as rice bran is to be processed, and there is the
problem of oil
degradation during storage, it is advisable to stabilize the rice bran using
the moisture/heat/partial
vacuum procedure previously described. Rice bran which could be stored
(without significant
degradation) about 7 days or less without this stabilizing procedure can then
be stored from about
2 to about 4 months (depending on temperature and humidity conditions). Thus,
if rice bran is to
be shipped a considerable distance prior to processing for oil extraction, it
is advisable to treat it
for stabilization prior to shipment.
The same technique used for rice bran stabilization can be applied to increase
porosity of
a grain material in preparation for extraction of the oil.
FIG. 2 shows a schematic of the process steps which can be used to make the
grain material
more porous, enabling extraction of the oil contents via solvent extraction.
This combination of
process steps can also be used to stabilize the oil content of the grain
material when it contains
enzymes which may cause degradation of the oil with time. As an alternative to
increasing
porosity, the grain material may be processed through mechanical size
reduction equipment,
whereby the availability of the oil for extraction by a solvent contacting the
grain material is
increased. However, such mechanical size reduction is an energy intensive
operation and relatively
expensive. The preferred method of making the oil more available for
extraction is to create
porosity within the grain material using moisture contained within the grain
material.
Typically the grain material as received from suppliers contains about 6
percent by
weight water (moisture) to about 11 percent by weight moisture. It is
preferred to increase this
moisture level to range between about 12 percent by weight to about 16 percent
by weight to
provide effective porosity increasing action. The method of increasing the
moisture level in the
grain material is dependent on the physical form of the grain material itself;
however, typically the
moisture content is increased by spraying the grain material with water and
allowing the sprayed
grain material to stand for about 24 hours at ambient temperature
(77°F.) at ambient pressure.
WO 94/00541 PCT/US93/05599
With reference to FIG. 2, the grain material is treated in process step 210 to
provide the
desired moisture content, then heat is applied in step 212, typically by such
means as contacting
of the grain material with steam, until the temperature of the grain material
ranges between about
100°F and about 215°F. A partial vacuum, is applied in step 216
to provide an absolute pressure
on the surface of the grain material which ranges between about 0.3 in. Hg and
about 25 in. Hg
at the surface of the heated grain material to cause the moisture in the grain
material to expand
rapidly, creating porosity within the grain material. The temperature to which
the grain material
must be heated is dependent on the amount of vacuum applied; one skilled in
the art can, with
minimum experimentation, determine the optimum conditions for a particular
grain material.
Typically the grain material is fed through rotating air locks into the upper
portion of a chamber
which is at the partial vacuum specified above. The grain material falls via
gravity into a lower
portion of the chamber from which the porous grain material can be fed into
the solvent extraction
process for the removal of oil or can be cooled and stored for subsequent
processing. An
alternative method for increasing porosity of the grain material is shown in
FIG. 2, step 214,
wherein an increase in moisture content is achieved simultaneously with
heating of the grain
material, using steam contact with the grain material. Subsequently, the
heated grain material is
exposed to a partial vacuum as shown in step 216.
FIG. 3 illustrates one preferred embodiment of an apparatus for increasing the
porosity of
a grain material prior to solvent extraction of the oil from the grain
material. Referring to FIG.
3, the apparatus 300 comprises a hopper 310 to hold the grain product which
has been treated to
increase the moisture content to at least 6 percent by weight. Preferably the
grain material has
been treated to a moisture content ranging from.about 12 to about 14 percent
by weight. Beneath
hopper 310 is air lock 311 which enables maintenance of a pressure
differential in steam pressure
chamber 312. The grain product from hopper 310 passes through air lock 311
into steam pressure
chamber 312 where it is heated by steam to a temperature ranging from about
100°F to about
215°F, without significant decrease in moisture content. Steam is fed
into steam pressure chamber
312 through steam distributor 314 and exits chamber 312 through a pressure
relief valve 316
located in the upper portion of chamber 312. The grain product is held in
chamber 312 until
temperature probe 318 indicates that the grain product is at the proper
temperature, at which time
a controller 322 actuates air lock 323 to permit the grain to pass into vacuum
chamber 326 in
which expansion of the grain product occurs. Vacuum chamber 326 typically
contains baffles 330
to direct the flow of the grain material toward the exit from vacuum chamber
326 through air lock
328. The absolute pressure in vacuum chamber 326 is typically maintained
through vacuum line
324, so that the upper portion of vacuum chamber 326 is at an absolute
pressure ranging from
about 0.3 in. Hg to about 25 in. Hg, while the lower portion of vacuum chamber
326 is at
11
WO 94/00541 PCT/US93/05599
atmospheric pressure. Gravitational force is used to cause the grain product
to exit the base of
vacuum chamber 326 through air lock 328.
The prepared grain material, processed in one of the manners described above,
is then
contacted with a solvent to extract the oil content of the grain material. The
oil can be extracted
by counter-current stripping under vacuum with a solvent in vapor form. For
example, the grain
material moves downward through a column, via gravity assist, as the stripping
solvent vapor
moves up the column, drawn up by a partial vacuum applied in the upper portion
of the column.
The interior of the column can contain various baffle and ring formations to
direct the grain
material as it flows toward the bottom of the column. In one preferred column
design, the column
contains a spiral-shaped conveyor for the grain material, with an exterior
vibrator to help keep the
grain material moving downward along the conveyor toward a collection area at
the bottom of the
column. There are numerous possibilities for transporting the grain material
in such a manner that
it contacts the solvent vapors for a period of time sufficient to achieve
extraction of the desired
amount of oil.
A preferred apparatus for use in extraction of oil from a grain material or a
grain-based
food product is shown in FIG. 4A. Vapor contact extractor 400 is comprised of
air lock 410 from
which the grain material or grain product enters vapor contact extractor 400.
From air lock 410,
the grain material or grain-based food product is deposited onto a moving,
perforated conveyor belt
412. Extraction solvent vapor 414 flows upward through perforated conveyor
belt 412 and through
the grain material or grain-based food product conveyed on the surface
thereof. General solvent
vapors flow toward flue 416 which is used to collect a first solvent/extracted
oil vapor component.
Flue 416 leads to a collection vessel (not shown). Typically a condenser (not
shown) is used in
combination with flue 416 to reduce the volume of the first solvent/extracted
oil vapor component
and to create a partial vacuum within flue 416. The grain material or grain
product on perforated
conveyor belt 412 has on its surface a second, liquid solvent/extracted oil
component which must
be recovered. Various suction techniques or centrifugation can be used to
separate this second,
liquid solvent/extracted oil component from a grain material surface. For
example, suction tubes
418 can be extended just below the surface of a grain material to remove the
second, liquid
solvent/extracted oil component which has migrated toward the upper portion of
the layer of grain
material on perforated conveyor belt 412. In the case of a grain-based food
product such as a chip,
cracker or noodle, such products are more fragile; and, typically partial
vacuum is used in
combination with heat to remove the second, liquid solvent/extracted oil
component from the
surface of such a grain-based food product.
FIG. 4B shows an apparatus for further, continued removal of the second,
liquid
solvent/extracted oil component from the surface of the grain material or
grain-based food product.
12
- 2Z3~~39'3
WO 94/00541 PCT/US93/05599
Oil separation extractor 450 can be a continuation of vapor contact extractor
400 or can be an
auxiliary processing apparatus. In the oil separation extractor 450 shown in
FIG. 4B, grain
material enters air lock 460 and is deposited onto a moving, perforated
conveyor belt 462. The
second liquid solvent/extracted oil component is separated from the grain
material using a partial
vacuum applied beneath perforated conveyor belt 462 by vacuum sources 464.
Gas, either air or
an inert gas such as nitrogen is permitted to enter oil separation extractor
450 through gas intake
means 466, to permit proper operation of the partial vacuum draw upon the
grain material. An
inert gas is used when the presence of oxygen would alter the oil product
obtained or create a risk
of fire or explosion. The grain material exiting from oil separation extractor
450 can be further
processed into food and feed products as previously described.
Oil/solvent components collected from grain materials or from grain-based food
products
using the suction tubes and vacuum collection system, as appropriate, can be
further processed to
provide oil products containing various amounts of saturated and unsaturated
constituents, as
previously described. When the oil is removed from a grain product, this oil
can be separated from
the extraction solvent using known distillation techniques and can be recycled
back into the original
preparation process for the grain product.
The amount of oil to be extracted from a grain material depends on the
products to be
produced from the grain material. Since the extracted grain material, Marc, is
subsequently
processed into food and feed products, it may be desirable to leave a
particular minimum oil
content in the Marc. Applicants have easily reduced the oil content of rice
bran from about 20
percent by weight to less than 1 percent by weight in a laboratory apparatus,
using counter-current
solvent extraction with ethyl acetate vapor. The amount of oil extracted
depends on the contact
time between the grain material surface and the solvent vapor, the
concentration of oil in the vapor
which is in contact with the grain material surface (overall volume of vapor
per volume of grain
material used during the stripping operation), the temperature, and the
pressure during the solvent
extraction operation. Applicants observed, during rice bran processing that a
grain material contact
time (residence time in a stripping apparatus column) with ethyl acetate
vapor, at about 180 °F,
ranging from about 30 seconds to about one minute, at a partial pressure
ranging from atmospheric
at the column base to about 0.1 in. Hg at the top of the stripping apparatus
column, when the
weight of solvent to weight of rice bran utilized is approximately 3 to 1,
reduces the rice bran oil
content from about 21 percent by weight to about I percent by weight. To
preserve the stripping
apparatus column vacuum, air locks were used at the top and the bottom of the
stripping column.
One skilled in the art can devise other schemes for contacting the grain
product with the
solvent vapors, to obtain oil extraction. There are numerous kinds of
equipment which can be used
for this purpose. The critical features are: 1) that the grain material,
flaked vegetable matter or
13
WO 94/00541
PCT/US93/05599
grain-based food product provide su~cient extraction surface from which the
oil can be removed;
2) that the proper solvent be used and that at least the initial contact
between grain material and
solvent be made with the solvent in vapor form; 3) that the temperature during
the solvent
extraction be maintained as low as possible (typically less than 210
°F) to avoid degradation of the
oils and proteins within the grain material; 4) that a sufficient amount of
solvent be used that the
concentration of oil in the extraction solvent vapors at the grain material
surface be su~ciently low
to have a driving force for migration of the oil from the grain material into
the solvent vapor
(typically this is assisted by the use of counter-current flow between the
solvent and the grain
material); and, 5) that in view of these factors, the contact time between the
solvent vapors and
the grain material be su~cient to permit the desired amount of extraction of
oil from the grain
material.
The preferred solvent for use in stripping the oil from the grain material is
one which forms
a weak bond with the oil molecules; this weak bond permits separation
processes whereby the oil
is removed from the grain material and whereby a saturated oil/solvent
fraction can be separated
from an unsaturated oil/solvent fraction, but is weak enough that when a
moderate amount of
energy is applied, the solvent can be separated from the oil. Typically this
latter separation is
achieved using a distillation process. Applicants have discovered that
solvents such as an acetate
or an alcohol or similar molecular structure capable of forming a hydrogen
bond with the oil
molecule can perform well as an oil stripping solvent. Preferred solvents are,
for example, methyl
acetate, ethyl acetate, methanol, ethanol, isopropyl alcohol, hexyl alcohol,
dexyl alcohol, or dectyl
alcohol. Such solvents can be used alone or in combination. The most preferred
of these solvents
are those which are already approved by the Food and Drug Administration. One
skilled in the
art can, with minimum experimentation, determine which of these solvents is
optimum for use in
combination with a particular grain material. Applicants have determined that
ethyl acetate works
particularly well with rice bran, for example.
After the oil has been stripped from the grain material, the resulting Marc is
separated from
the solvent, which solvent is then recycled into the stripping process.
Typically the solvent is
removed using a rotary drum dryer operated at a low temperature, preferably
under the assist of
a partial vacuum, which enables solvent removal at a lower temperature. Such
solvent removal
processes are well known within the food processing industry.
The oil/solvent composition obtained from the stripping operation can be
distilled to
separate the various oil constituents from the solvent; however, complete
breakdown to individual
oil constituents is not generally necessary. The oil comprises a variety of
molecular structures
having various degrees of saturation. It is well known that the saturated fats
contained in this oil
fraction have undesirable effects on human health when allowed to accumulate
in the body over an
14
WO 94/00541 ,~~ PCT/US93/05599
extended time span. Therefore, it would be highly desirable to provide an oil
composition from
which a large portion of these saturated fats (oils) have been removed.
Applicants have discovered
an economical method of processing the oil composition obtained from the above-
described
stripping operation to produce an oil fraction substantially reduced in
saturated oil content.
FIG. 5 shows a schematic of a preferred process wherein the oil/solvent
composition
obtained from a grain material oil extraction operation is processed through a
separation apparatus
wherein the lighter oils, comprising principally saturated oils and waxes are
separated from the
heavier oils, comprising principally unsaturated oils and fatty acids. With
reference to FIG. 5, the
extracted grain oil/solvent composition is fed to an apparatus which utilizes
gravity flow of the
composition components combined with variable vacuum in a mufti-chamber
process vessel in step
510, to separate a principally saturated oils and waxes/solvent fraction 512
from a principally
unsaturated oils and fatty acids/solvent fraction 516. The lighter fraction
512, comprising
principally saturated oils, can then be separated in step 514 (typically via
distillation under partial
vacuum) to provide a saturated oil and wax product as well as a fatty acid
product and a solvent
for recycle into the solvent extraction step 112 shown in FIG. 1. The heavier
fraction 516,
comprising principally unsaturated oils and fatty acids, can then be separated
in step 518 (typically
by distillation under partial vacuum) to provide a principally unsaturated
oils product and a fatty
acids/solvent composition. This latter composition can be further separated in
step 520 (via
distillation) to provide a fatty acid product and solvent for recycling to the
oil extraction operation.
FIG. 6 shows two preferred embodiments of an apparatus which can be used to
achieve the
separation of extracted oil/solvent components as shown at 118 in FIG. 1. With
reference to FIG.
6, separation is achieved in process vessel 600 having five chambers in which
various steps of the
separation process take place. The extracted oil/solvent composition enters
through a feed line 602
into a central feed inlet chamber 604 of vessel 600. Feed inlet chamber 604
may be simply an
open housing or may contain baffles (not shown) to direct the flow of the
extracted oil/solvent
composition feed. The feed rate into feed inlet chamber 604 can be constant or
can be pulsed, that
is periodic. The feed may enter through a spray nozzle (not shown), through a
control valve (not
shown) or simply through a pipeline. The pulsed feed can be achieved using a
pump or a control
valve set to produce a periodic supply of the feed, or can be achieved by
periodic application of
the vacuum source used to create the desired vacuum profile within the
apparatus. A pulsed feed
rate to feed inlet chamber 604 has been shown to provide significantly
improved separation over
the separation obtained using a constant feed flow.
The lighter oillsolvent fraction of the extracted oil/solvent composition
feed, drawn by a
partial vacuum applied at the top 624 of vessel 600 moves upward past retainer
screen 616A (used
to retain packing 612) into chamber 606 which is filled with a packing 612.
Packing 612 can be
i~~
WO 94/00541 PCT/US93/05599
any inert packing known within the chemical industry. One inert packing which
has been observed
to work particularly well is a ceramic interlock saddle type of packing.
The lighter oil/solvent fraction, which comprises principally saturated oil
and waxes in
combination with solvent, then passes through retainer screen 616B, and enters
chamber 628 which
is typically open, but which can contain baffles (not shown) to direct the
flow of the lighter
oil/solvent fraction. The lighter oil/solvent fraction, principally comprising
saturated oils and
waxes in combination with solvent, can then processed (apparatus not shown) to
separate the oils
and waxes from the solvent, as previously described.
The heavier oil/solvent fraction, which comprises principally unsaturated oil
and fatty acids
in combination with solvent, is pulled via gravity from central feed inlet
chamber 604 downward
through packing retaining screen 618A into chamber 608 which is also filled
with a packing 614,
further downward through retainer screen 618B, through typically open area
630, and exits at the
bottom 626 of vessel 600. Packing 614 can be any inert packing of the kind
used in the chemical
industry to accomplish separations. Packing 614 can be the same as or
different from packing 612.
The heavier oil/solvent fraction having passed through retainer screen 618B
enters chamber
630 which is typically open, but which can contain baffles (not shown) to
direct the flow of the
heavier oil/solvent fraction to the vessel exit 626. The heavier oil/solvent
fraction, principally
comprising unsaturated oils and fatty acids in combination with solvent can
then be further
processed as previously described.
Not all of the separation of the light oillsolvent fraction from the heavy
oil/solvent fraction
occurs in fed inlet chamber 604. There is a migration of a portion of heavy
oil/solvent fraction
into chamber 606 and a migration of a portion of light oil/solvent fraction
into chamber 608.
These packed chambers are used to further accomplish separation, with the
lighter oil components
eventually working their way toward the top of vessel 600 and exiting at the
top 624 through a take
off line (not shown) and the heavier oil components eventually working their
way toward the
bottom of vessel 600 and exiting at 626. However, a surprising amount of
separation of the
fraction comprising the light oil from the fraction comprising the heavy oil
occurs in centrally
located feed inlet chamber 604. The extracted oil/solvent composition feed
enters feed inlet
chamber 604 as a vapor or is converted to a vapor immediately upon entrance to
feed inlet chamber
604 due to the partial vacuum applied to the upper portion of chamber 628
through the top 624 of
vessel 600. Presence of a relatively open compartment 604 in the central area
of vessel 600
permits a free exchange of vapor and prevents condensation of the vapor which
could otherwise
occur due to back pressures developed within other portions of vessel 600.
Once the oil/solvent
composition vapor enters feed inlet chamber 604, the vapor cam move up or down
or sit at
equilibrium. Gravity forces the heavier molecules to fall downward and either
heat or pressure or
16
WO 94/00541 PCT/US93/05599
a combination thereof forces the lighter molecules to move upward in vessel
600. Use of the
pulsed flow of the extracted oil/solvent composition feed to feed inlet
chamber 604 permits the
molecules to sort out better by permitting the vacuum in feed inlet chamber
604 to build up,
assisting in the gravimetric separation by avoiding creation of a back
pressure in chamber 606. The
longer the pulse interval, the more saturated oils will exit 624 at the top of
vessel 600. The shorter
the pulse interval, the more saturated oils will exit 626 at the bottom of
vessel 600. The pulse
length can be adjusted with minimal experimentation to provide the desired
product stream at exits
624 and 626.
Additional solvent (preferably the same solvent as that used in the solvent
extraction process
described with reference to FIG. 1) can be introduced into vessel 600 to
further facilitate the
separation process. This additional solvent is typically added in vapor form
near the bottom of
vessel 600 to further facilitate the separation process. This additional
solvent is typically added in
vapor form near the bottom of vessel 600 at inlet 610 into chamber 630. This
solvent addition can
be at a constant rate or can be pulsed in the manner described for the
extracted oil/solvent feed
stream.
FIG. 6B illustrates a less preferred embodiment of the separation apparatus,
wherein the
central open chamber is not expanded as it is in FIG. 6A. The extracted
oil/solvent feed enters
separation vessel 650 through entry 652 to central feed inlet chamber 654
which may contain
baffles (not shown) for directing the feed, as previously described with
reference to FIG. 6A. The
lighter oil/solvent components of the feed tend to migrate upward through
retaining screen 666A,
and through chamber 656 which contains packing 662. Due to the partial vacuum
applied through
the top 674 of chamber 678, the lighter oil/solvent fraction continues in
upward travel through
retaining screen 666B, through relatively open chamber 678 (which may contain
baffles, as
previously described), and out the top 674. The heavier oil/solvent components
of the feed tend
to migrate downward through retaining screen 668A, and through chamber 658
which contains
packing 664. Due to gravitational forces, the heavier oillsolvent fraction
progresses downward
through retaining screen 668B into relatively open chamber 680 (which may
contain baffles) and
exits through the bottom 676 of chamber 680.
The temperature and pressure conditions which are utilized within the
separation chamber,
the kind of packing, and the length of feed pulse (or vacuum pulse) will
depend on the composition
of the feed stream to be separated.
As previously described with reference to FIG. 6A, additional solvent can be
added through
inlet 660 into relatively open area 680. Open area 680 may contain solvent
vapor directing baffles
if desired. One skilled in the art, with in view of the disclosure provided
herein, can develop the
conditions which provide optimum processing of the extracted oil/solvent feed
with minimal effort.
17
WO 94/00541 ~~.~~'~PCT/US93/05599
Example 1 below provides a detailed description of the separation of an
extracted
oil/solvent composition feed obtained from rice bran into a principally
saturated oils and waxes
fraction and a principally unsaturated oils and fatty acids fraction.
EXAMPLE 1
This example discloses a preferred embodiment of the method of separating an
extracted
rice bran oil/ethyl acetate solvent composition into a principally saturated
oil fraction, a principally
unsaturated oil fraction, a fatty acids fraction and an ethyl acetate
fraction.
An extracted oil/solvent composition in liquid form comprising about 25
percent extracted
rice bran oil and about 75 percent ethyl acetate was continually fed to a
separation apparatus using
a pulsed flow rate. The overall flow rate was about 250 g. per minute. The
pulsed feed was
obtained using a control valve which permitted flow of composition to the
separation apparatus for
a period of about 10 seconds, followed by absence of flow for about 2 minutes,
with this cycle
repeating during operation of the separation apparatus. The separation
apparatus consisted of a
glass tube and valve assembly having an inside diameter of about 2 inches,
which was about 27 1/2
inches long. The feed composition entered a valve into a central first
volumetric area about 1-1/2
inches in length which was essentially open (unpacked). This central volume
area was under a
vacuum such that an absolute pressure ranging from about 3 in. Hg to about 25
in. Hg was present
therein. The entering liquid feed, at a temperature of about 190°F.,
volatilized upon entry into the
open valve area. The volatilized oil/solvent feed composition immediately
began to separate.
A principally saturated oil/solvent fraction progressed upward toward a second
volumetric
area of the glass tube which was filled with 3/8 in. stainless steel porous
saddles as packing. This
second volumetric area was about 12 inches in length and at an absolute
pressure ranging between
about 3 in. Hg and about 25 in. Hg. At the top of the packed second volumetric
area was a fourth
volumetric area which was open (about 1 in. in length). The volatilized
saturated oil/solvent
fraction was removed from this open area and subsequently condensed.
A principally unsaturated oil/solvent fraction progressed downward into a
third volumetric
area of the glass tube which was also filled with 3/8 in. stainless steel
porous saddles as packing.
This third volumetric area was also about 12 inches in length. The absolute
pressure in the upper
portion of this third volumetric area ranged between about 5 in. Hg and about
25 in. Hg increasing
to atmospheric pressure at the bottom of the third volumetric area. At the
bottom of the packed
third volumetric area was a fifth volumetric area which was open (about 1 in.
in length). The
volatilized unsaturated oil/solvent component was removed from this open area
and subsequently
condensed.
No heat was added to the separation apparatus other than the heat from the
extracted rice
bran oil/solvent composition.
18
238393
WO 94/00541 PCT/US93/05599
Approximately 20 percent by weight of the original extracted rice bran
oil/solvent
composition feed was collected from the top of the apparatus as principally
saturated oil/ethyl
acetate fraction and approximately 80 percent by weight of the feed
composition was collected from
the bottom of the apparatus as principally unsaturated oil/ethyl acetate
fraction.
S Each fraction collected was subsequently condensed and stored for future
processing.
The condensed components were then heated in a rotating evaporator operated at
an
absolute pressure of about 0.5 in. Hg. The rotating evaporator was heated by
an oil bath. The
ethyl acetate solvent was thereby removed from the saturated or unsaturated
oil (desolventizing).
EXAMPLE 2
This example discloses a preferred embodiment of the method of extracting the
oil
contained in rice bran, using an ethyl acetate solvent which is in vapor form
at the time it initially
contacts the rice bran.
Rice bran, 24 hrs. after milling, was processed through an oil stripping
apparatus. The
composition of the rice bran was as follows:
Rice Bran Starting Material
Component Weight Percent
Carbohydrates 46.0
Moisture 9.1
Protein 10.1
Fat 12.3
Fiber 16.6
Ash 5.7
The rice bran sieve was such that about 81 % of the bran remained on top of a
U.S.S. #80
mesh screen, with about 19 % passing through the screen. Approximately 400 g.
of the rice bran,
at room temperature, was placed in a 500 ml. glass separatory vacuum funnel
having a valued
bypass loop. About 750 ml. of ethyl acetate stripping solvent vapor at a
temperature of about
175 °F. was pulled upward through the rice bran using a vacuum. The
flow rate of the ethyl
acetate through the rice bran was approximately 20 ml. per minute. The ethyl
acetate formed a
weak bond with oil contained in the rice bran and this oil was carried out of
the vacuum funnel
with the ethyl acetate vapors passing through the rice bran.
The vacuum source used to pull the ethyl acetate vapor through the rice bran
was a 2 gallon
mechanical aspirator manufactured by Cole-Parmer. This vacuum source was
attached to a 200
ml. Liebig condenser which was attached to a 1,000 ml. flask into which the
extracted oil/ethyl
acetate composition was collected after exiting the S00 ml. glass separatory
vacuum funnel.
Typically the amount of vacuum applied was such that the absolute pressure at
the top of the 500
ml. glass separatory vacuum funnel was about 3 in. Hg. The dew point of the
extracted oil/ethyl
acetate composition was 67°F. and the condenser was operated at a
temperature of about 40° F.
19
WO 94/00541
2.38393 PCT/US93/05599
,:
No heat other than the heat from the 175 °F. ethyl acetate stripping
solvent vapor was added
to the extraction process.
The extracted oil/ethyl acetate composition contained about 14 % by weight
extracted rice
bran oil, with the rice oil having the following composition:
Carbons in Molecule: Fatty Acid Weight
Double Bonds Present Name Percent Form
C10 Cupric 0.0 Saturated
C 11 Undecanoic 0.0 Saturated
C12 Lauric 0.0 Saturated
C14 Myristic 0.93 Saturated
C 14:1 Myristoleic 0.0 Saturated
C15 Pentadecanoic0.0 Monounsaturated
C16 Palmitic 17.32 Saturated
C16:1 Palmitoleic 0.0 Monounsaturated
C18 Stearic 2.45 Saturated
C18:1 Oleic 44.74 Monounsaturated
C18:2 Linoleic 30.07 Polyunsaturated
C18:3 Linolenic 0.98 Polyunsaturated
C19 Nonadecanoic0.68 Saturated
C20 Arachidic 0.44 Saturated
Carbons in Molecule:Fatty Acid Weight
Double Bonds PresentName Percent Form
C20:1 Gadoleic 0.67 Monounsaturated
C21 Heneicosanoic0.0 Saturated
C22 Behnic 0.0 Saturated
C24 Lignoceric 1.73 Saturated
Total Saturated: 23.55
Total Monounsaturated: 45.41
Total Polyunsaturated: 31.04
By comparison, rice
oil extracted from the
same rice bran starting
material, but
extracted using liquid in a soxhlet
hexane extractor
had the following
composition:
Carbons in Molecule: Fatty Acid Weight
Double Bonds Present Name Percent Form
C14 Myristic 0.289 Saturated
C16 Palmitic 16.713 Saturated
C18 Stearic 1.823 Saturated
C18:1 Oleic 42.183 Monounsaturated
C18:2 Linoleic 36.739 Polyunsaturated
C18:3 Linolenic 1.379 Polyunsaturated
C19 Nonadecanoic 0.28 Saturated
C20 Arachidic 0.595 Saturated
C21 Gadoleic 0.0 Saturated
C24 Lignoceric 0.0 Saturated
WO 94/00541 ~ . ~ .~ A t- PCT/US93/05599
~~~a~
A comparison of the rice oil extracted by the method of the present invention
with the
rice oil extracted using liquid hexane as the extraction solvent shows that
the overall extraction
of saturated oils is slightly higher (possibly within experimental error) for
the ethyl acetate
vapor extraction than for extraction using liquid hexane as the solvent.
The composition of the Extracted Rice Bran after oil extraction using ethyl
acetate vapor
as the extraction solvent was as follows:
Component Weight Percent
Carbohydrates 43.2
Moisture 9.0
Protein 14.5
Fat 2.7
Fiber 22.5
Ash 8.0
EXAMPLE 3
This example discloses a preferred embodiment of the method of increasing the
porosity
of rice bran in preparation for the extraction of oil therefrom.
Approximately 400 g. of rice bran previously described, less than 24 hrs.
after milling,
was placed in a plastic container and covered with water and allowed to stand
at room
temperature for about 12 hrs. The rice bran became saturated with water such
that the moisture
content was about 17 percent by weight.
This saturated rice bran was placed in a 500 ml. glass separatory vacuum
funnel
wrapped with electric heating tape. The funnel was heated until the
temperature of the rice
bran was raised to about 215 °F. under the pressure generated
internally (that is, the funnel was
closed to ambient atmosphere).
The 215 °F. rice bran was then dropped through a valve at the bottom of
the 500 ml.
separatory vacuum funnel into a 1,000 ml. glass retort which was at an
absolute pressure of
about 3 in. Hg. The retort was maintained at this partial vacuum using a 2
gal. mechanical
aspirator pump manufactured by Cole-Parmer.
The rice bran expanded upon entering the glass retort such that the volume of
the rice
bran increased at least twice. This expansion produced porosity which enabled
subsequent
extraction of the oil contained in the rice bran.
The preferred embodiments of the present invention, as described above and
shown in
the Figures are not intended to limit the scope of the present invention, as
demonstrated by the
claims which follow, since one skilled in the art can) with minimal
experimentation, extend the
scope of the embodiments to match that of the claims.
21
