Note: Descriptions are shown in the official language in which they were submitted.
3271
REFINING OF
OIL AND PROD CT THEREOF
SUMMARY OF THE INVENTIQN
The present invention relates to the reining of
crude vegetable oils. In particular, the present invention
relates to the refining of such crude oils containing impuri-
ties to produce an essentially additive free product having
good oxidative, flavor and cold-test stabilities.
BACRGROUND OF THE INVE TION
In the past, edible fats and oils derived from
animal sources were refined for use by physical refining
methods. Vegetable oils however could not be satisfactorily
refined by these methods. The many and varied impurities
vegetable oils might contain would cause undesirable charac-
teristics, such as dark colors or off-flavors or the like~
in the finished oils.
At present, the most common method o refining
vegetable oils is the treatment of crude oils with an alka~i.
Alkali refining removes free fatty acids and other acidic
materlals, some phosphatides, proteinaceus matter, pigments
and trace metals. Until recently, most oils could not be
deodorized satisfactorily unless they had been alkali refined.
However, although alkali refining is suitable for preparation
of oils for fur~her processing steps, such as bleaching and
deodorization, it has some serious disadvantages also~
Alkali refining typically results in a high loss
of the neutral oil components of the crude oil, reducing the
amount of yield of the refined oil product. In addition,
the removal of free ~atty acids by alkali refining results
in the production of soapstock which has to be further pro~
cessed in order to recover the fatty acids as a by-product.
Further, alkali refining typically results in a large amount
of waste water, often causing a serious water pollution prob-
lem. Alkali refined oils are additionally disadvantageous
in that the finished oils require stabilizers, typically
antioxidents or citric acid, or the like, to maintain accept~
able flavor characteristics and prevent harmful oxidation on
storage.
Alkali refining also involves a dewaxing step which
increases the cost of the refined oil. This additional ste~
removes such low temperature insoluble compounds, which are
generally referred to as waxes although these compounds are
not limited to compounds which are classed as waxes in a
strict chemical sense. Without this processing step of
chilling the oil and removing the solids rormed, the finished
oil would not have acceptable cold~test stability, i.e. it
would not retain good clarity during storage at 0C for 24
hours.
Various processes for the physical refining of
vegetable oils have been proposed over the last few decadesO
Some of these have been successful with certain crude oils
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:,
5`~.
containing limited amounts and types of impurities. For
example, U.S. Patent No. 1,744,843 to Taylor, et al, relates
to the process of bleaching animal and vegetable oils and
fats and comprises adding bleaching earth and sulfuric acid.
The bleaching earth is added at least as early in the process
as the acid so that the fat or oil is exposed to the acid
only in the presence of the bleaching earth. The mixture is
agitated and the supernatant oil is drawn off and filtered
through a layer of diatomaceous earth.
UOS. Patent No. 1,964,875 to Freiberg relates to an
alkali-refining process, and discloses a method of removing
impurities from oils and fats in which the oils or fats are
mixed with a small quantity of concentrated phosphoric acid.
The mixture is then heated slowly to about 70C. and stirred,
and a small quantity of cellulose is added. When the action
of the phosphoric acid and the cellulose is complete, the oil
is separated by filtration.
U.S. Patent No. 1,973,790 to Appleton relates to
the method of purifying non-edible vegetable oils to increase
their heat stability for use in paints. The oil is purified
by thoroughly mixing it with an amount of phosphoric acid
which is sufficient to react with the impurities in the oil.
This will cause such impurities to be precipitated and settle
out of the oil in the form of a sludge. The purified oil is
then segregated from the sludge.
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1~3'7~
U.S. Patent No. 2,441,923 to Sullivan, although
itself not relating to physical refining, does disclose that
acid-activated adsorptive material such as Fuller's earth can
be used to remove residual color from alkali refined oil.
U.S. Patent No. 2,510,379 to Christenson relates to
a method of removing lecithin, other phosphatides and color-
ing matter. .~fter the treatment of the oil with an alkali,
the oil is further treated with an equivalent amount of a
strong acid, and resultant salt produced by the alkali and
the acid is removed. Phosphoric acid and other strong acids
are used to neutralize the oil (column 2 lines 35-42). The
reference also shows the use of acid activated bleaching clay
(column 4 lines 10-15).
U.S. Patent No. 2,587,254 to Babayan relates to a
method for reclaiming contaminated refuse palm oil used in
steel fabrication~ According to this method the refuse palm
oil is treated with from 1% to 5% (by weight) of either
phosphoric acid, sulfuric acid or hydrochloric acid in at
least 50~ water (by weight of oil) at some temperature from
0C. to 100C. T~e mixture is allowed to stratify and the
oil layer is separated from the aqueous layer and bleached.
U.S. Patent No. 2,903,434 to Gloss et al relates
not to the refining of oils, but to the preparation of
activated bleaching clay. Montmorillonite clay is treated
with an aqueous solution of a fluorine compound and either
hydrochloric, phosphoric or sulfuric acid.
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~'7~
U.S. Patent No. 2,981,6~7 to Mickelson et al shows
a process for the preparation of an acid-activated decoloriz-
ing clay. An acid-activatable su~bentonite clay is treated
with hydrogen chloride in aqueous solution and then washed
with water until substantially free of chlorides. Then the
washed clay is treated with either sulfuric acid or phosphoric
acid at a temperature below about 50C. to remove the residual
chlorides. Excess acid is removed from the clay, and the clay
is flash-dryed at temperatures below 100C.
U.S. Patent No. 3,284,213 to VanAkkeren discloses
a process ~or treating triglyceride cooking oils to inhibit
breaXdown during heating and to prevent oaming. About 0.05
to 3.5% of concentrated phosphoric acid is added to the oil,
and the oil is heated slowly to a temperature of about 100C.
and stirred slowly to prevent the formation of free acid in
the oil. Bleaching clay is added to the oil when the tempera-
ture has reached about 100C. and the mixture is then heated
to about 120C. for about 15-30 minutes. The oil is first
cooled and filtered to remove the clay and phosphoric acid
material, and then heated to about 220-225C. under reduced
pressure. The reference teaches that it is importan~ to
remove all of the phosphoric acid with the bleaching clay
prior to the final heat treatment. A ratio of phosphoric
acid to clay up to 1:10 can be calculated from the examples.
U.S. Patent No. 3,354,188 to Rock et al shows a
method of refining oil in which a refining agent substan-
'75:L~
tially insoluble in the oil is first combined with an emulsi-
fying agent, and then mixed with the oil to form an emulsion.
A particulate solid, such as Fuller's earth, activated clay
or charcoal is then added to adsorb the refining agent and
the oil i5 separated from the solid. Phosphoric acid is
listed among the refining agents.
U.S. Patent No. 3,590,059 to Velan discloses a
process for the purification of vegetable and animal oils
containing fatty acids and other impurities. The crude or
degummed oil is first washed with about 1 to 5% by weight of
water and the aqueous phase is separated from the resultant
mixture. The washed oil ls then treated with less than 0O3%
by weight of organic acid, such as formic, acetic, o~alic,
lactic, citric, tartaric or succinic acids or the anhydrides
of any of these acids or mixtures of these acids. The
moisture level of the oil is adjusted and the oil is bleached
with a bleaching earth. Following this, the bleached oil
is steam distilled under ~acuum to remove fatty acids. The
use of mineral acids, rather than organic acids, is also
suggested.
Great Britain Patent No. 1,359,186 and U.S. Patent
No. 4,113,752 to Watanabe et al discloses a method of refining
palm-type oils. Essentially, 0.01 to 2.0% by weight of phos-
phoric acid is added to the crude palm-type oil, which is
substantially phosphatide-free and in which any carotinoids
remain substantially in a heat sensitive condition. After
~'75~:~
mixing, activated clay is added and the temperature is
increased to and maintained at about 100C. for about 5 to
30 minutes. Then the clay is separated from the oil and the
oil is refined-deodorized by steam distillation at a tempera-
ture of 200 - 270C. with superheated steam. The calculated
ratio of phosphoric acid to bleaching clay ranges from about
l Ool to 1:60~
U~S. Patent No. 3,895,042 to Taylor relates to a
process for refining crude vegetable oils as well as other
fatty substances. The crude fatty substances are heated to
a temperature of from about 325F. to 500F. under vacuum or
inert atmosphere in the presence of phosphoric acid and acid
activated clay. The resulting product is then filtered.
OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to provide
a process for the refining of crude vegetable oils.
It is a further object of the present invention to
provide a process for the refining of crude vegetable oils
containing such impurities as phospholipids, waxes and trace
metals.
It is a still further object of the present inven-
tion to provide a process for the refining of crude vegetable
oils in which the economically valuable by-products may be
more easily recoveredO
~3'75~1
It is another object of the present invention to
provide a refined oil product having increased stability of
flavor characteristics.
It is another object of the present invention to
provide a refined oil product having increased stability
against oxidation.
It is another object of the present invention to
provide a refined oil product having satisfactory cold-test
stability without the necessity for a separate winteriæing
step
The objects features and advantages of the present
invention will become more apparent in light of the following
detailed description of the preferred embodiment thereof.
According to the present invention, there is
provided a process for the refininy of crude vegetable oils
to provide a product having good oxidative, flavor and cold-
test stabilities, comprising the steps of:
(a) degumming the crude oil by
i) combining such a crude oil with a small
quantity of water to form a mixture,
ii) agitating said mixture, and
iii) separating the oil from the water and
precipitating impurities,
(b) degumming/demetalizing the degummed
:
-- 8 --
l~B'~511
oil obtained in step (a)(iii) by
i) combining said oil with a small amount
of a suitable degumming reagent known
to the art to form a mixture,
ii) agitating the mixture,
iii) combining the mixture with a small
amount of water,
iv) agitating said mixture, and
v)` separating the oil from the residual
impurities~
(c) bleaching the degummed/demetalized oil
obtained in step (b)(v) by
i) combining said oil with an amount of
phosphoric acid in aqueous solution
so as to form a mixture with at least
two one-hundredths of a percent
(0.02%) phosphoric acid by weight,
ii) maintaining the mixture at a suitable
temperature while agitating intensely
to allow reaction,
iii) combining the mixture thus treated
in step (c)(ii) with a bleaching agent
in such proportion as to allow in the
final product a level of up to three
parts per million (3 ppm) residual
phosphorus derived from the phosphoric
_ g _
5~
acid added in (c)(i),
iv) raising the temperature of the mixture
of step (c)(iii) under vacuum to a tempera-
ture suitable for the action of the chosen
bleaching agent and maintaining said tem-
perature while agitating said mixture.
v) cooling the mixture of step (c)(iv) to
a temperature at which the vacuum can be
broken, and
vi) filtering the bleached oil; then
(d) steam refining-deodorizing the bleached
oil obtained in step (c)(vi).
According to another embodiment of the present inven-
tion, there is provided a process for the refining of crude
vegetable oils to provide a product having yood oxidative,
flavor and cold-test stabilities, comprising the steps of:
(a) degu~ming the crude oil by
i) ~ombining said crude oil with a small
amount of water to form a mixture with
said oil,
ii) agitating said mixture,
iii) separating the oil from the water and
precipitating impurities;
(b) bleaching the oil obtained in step (a)(iii) by
i) combining said oil with an amount of
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~'7S~
phosphoric acid in aqeuous solution so
as to form a mixture with at least
two one-hundredths of a percent (0.02~)
phosphoric acid by weight,
ii) maintaining the mixture at a suitable
temperature while agitating intensely
to allow reaction,
iii) combining the mixture thus treated in
step (bj(ii) with a bleaching agent
in such proportion as to allow in the
final product a level of up to three
parts per million (3 ppm) residual phos-
phorus derived from the phosphoric acid
added in (b)(i),
iv) raising the temperature of the mixture
of step (b)(iii) under vacuum to a
temperature suitable for the actlon
of the chosen bleaching agent and
rnaintaining said temperature while
ayitating said mixture.
v) cooling the mixture of step (b)(iv)
to a temperature at which the vacuum
can be broken, and
vi) filtering the bleached oil, then
(c) steam refining-deodorizing the bleached
oil obtained in step (b)(vi).
5~
According to still another embodiment of the
present invention, there is provided a process for the
refining of crude vegetable oils to provide a product having
good oxidative, flavor and cold-test stabilities, comprising
th~. steps of:
(a) degumming/demetalizing the crude oil by
i) combining said oil with a small amount
of suitable degumming reagent known to
the art to form a ~ixture,
ii) agitating the mixture,
iii) combining the mixture with a small amount
of water,
iv) agitating the mixture,
v) separating the oil from the water and
lS precipitating impurities;.
(b) bleaching the oil obtained in step (a)(v) by
i) combining said oil with an amount of
phosphoric acid in aqeuous solution so
as to form a mixture with at least
two one-hundredths of a percent (0.02%)
phosphoric acid by weight,
ii) maintaining the mixture at a suitable
temperature while agitating intensely
to allow reaction,
iii) combining the mixture thus treated in
step (c)(ii) with a bleaching agent in
jt5~
such proportion as to allow in the final
product a level of up to three parts per
million (3 ppm) residual phosphorus
derived from the phosphoric acid added
in (b) (i),
iv) raising the temperature of the mixture
of step (b)(iii) under vacuum to a
temperature suitable for the action
of the chosen bleaching agent and
maintaining said temperature while
agitating said mixture.
v) cooling the mixture of step (b)(iv) to a
temperature at which the vacuum can be
broken, and
vi) filtering the bleached oil; then
(c) steam refining-deodorizing the bleached oil
obtained in step (b)(vi).
According to another embodiment of the present
invention, there is provided a process for the refining of
crude vegetable oils to provide a product having good oxida~
tive, flavor and cold-test stabilities, comprising the steps
of: .
(a~ bleaching the crude oil by
i) combining said oil with an amount of
25 . phosphoric acid in aqueous solution
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1'7'j~
so as to form a mixture with at least
two one-hundredths of a percent (0.02~)
phosphoric acid by weight,
ii) maintaining the mixture at a suitable
temperature while agitating intensely
to allow reaction,
iii) combining the mixture thus treated in
step (a)(ii) with a bleaching agent
in such proportion as to allow in the
final product a level of up to three
parts per million (3 ppm) residual phos-
phorus derived from the phosphoric acid
added in (a)(i~,
iv) raising the temperature of the mixture of
step (a)(iii) under vacuum to a tempera-
ture suitable for the action of the chosen
bleaching agent and maintaining said tem-
perature while agitatiny said mixture.
v) cooling the mixture of step (a)(iv) to
a temperature at which the vacuum can be
broken, and
vi) filtering the bleached oil; then
(b) steam refining-deodorizing the bleached oil
obtained in step (a)(vi).
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~8~'5~
DETAILED DESCRIPTION OF THE PRESE~T INVENTION
It has now been determined that an edible oil
having good flavor, oxidative and cold-test stability charac-
teristics can be obtained from a physical-type refining
process. The present invention provides an oil as a final
product with a level of up to three parts per million (3 ppm~
residual phosphorus derived from phosphoric acid used in the
process.
While the patentee does not wish to be bound to one
particular mechanismr it is presently supposed that the phos-
phoric acid added as a processing aid reacts with minor
components of the oil, such as chlorophyll, phospholipids
and prooxidant metals during processing and may prevent some
deliterious effect the bleaching earth would otherwise have
on the oil if the phosphoric acid were not present. It is
believed that the phosphorus has no further beneficial effect
after the bleaching step and its removal after action of the
bleaching earth would not alter the beneficial characteris-
tics of the oil of the present invention. However, since
the residual level of up to three parts per million (3 ppm)
phosphorus obtained in this manner is substantially lower
than the level permitted and often employed as an additive in
alkali-refined oils, it is believed that complete removal of
the processing aid is unnecessary. A residual level of up to
three parts per million (3 ppm) phosphorus in the finished
oil is undetectible as phosphoric acid by normal acidity
- 15 -
measurements and below the detectable level for phosphorus
using the approved test AOCS Official Method No. Ca 12 55.
Phosphorus present at the time of bleaching in the
form of phospholipids does not produce an oil having the
superior properties of the present invention. It is believed
that such phosphorus compounds have no ability to bind heavy
metals, such as iron and copper which promote o~idation.
To obtain a finished oil with these superior proper-
ties, the process must be carefully controlled to satisfac-
torily remove essentially all of the phosphoric acid withoutpermitting the oil to be exposed to the action of the bleach-
ing agent alone. The parameters for such a controlled
removal of phosphoric acid were determined experimentally.
Treatment of the oil ~ith an excess of bleaching agent would
remove all of the phosphoric acid. It is believed that this
would have the same effect as treatment of the oil with
bleaching agent alone, which would impair the oxidative
stability of the oil. At residual phosphorus levels above
three parts per million (3 ppm) some acidity becomes detect-
able and, although refined oils having a phosphorus levelthis high may have acceptable initial properties, such oils
do not retain these superior properties on storage.
In the present invention, a process is shown in
which an unrefined vegetable oil is first pre-treated to
remove impurities, then steam-refined to produce a finished
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~8'7~
oil having good oxidative, flavor and cold-test stabilities.
Vegetable oils are known to contain many different
types of impurities which must be removed prior to steam
refining. Crude oils may contain any or all of the follow-
ing: free fatty acids, hydratable phospholipids, non-
hydratable phospholipids, low-temperature insolubles
(aenerally referred to as "waxes"), trace metals, pigments,
proteinaceous matter, mucila~enous matter, mycotoxins,
pesticides and oxidation products. With the exception o~
cottonseed oil, which contains a dark red pigment generally
re~erred to as "gossipol" which is considered to be remov-
able only by treatment with alkali, the process of the
present invention can be applied to any of the commercially
available oils~ corn, soybean, peanut, safflower, sunflower,
rapeseed, rice bran, coconut, palm, palm kernel and babassu
oils.
These commercially known oils contain at least
some of the impurities listed above. Some, such as soybean
oil and rapeseed oil, typically contain relatively high
concentrations of hydratable and non-hydratable phospholipids
whereas the concentration o other impurities, such as low
temperature insolubles (waxes) may not present a removal
problem. Other oils, such as corn oil and sunflower oil,
may contain relatively high concentrations of waxes, or
trace metals, whereas phospholipids may not normally present
a removal problem.
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îJ5~
Still other oils, such as palm oil, palm kernel
oil or coconut oil may not have concentrations of impurities
which require removal prior to bleaching and steam refining.
Physical refining methods have previously been applied to
such oils with some success. The present invention, however,
provides for the refining of such oils with the beneficial
properties which could not be obtained with consistency
heretofore.
Most of the impurities referred to above do not
represent useful by-products and no attempt is generally made
to recover them. Free fatty acids and phospholipids can be
useful, however, and it is not unusual to attempt to recover
these. In an alkali refining process, the free fatty acids
removed are only recoverable from the soapstock produced and
are of generally low qualityO In the present invention,
phospholipids as removed are of better quality and can be
utilized for animal feed or the like, or further processed
to recover commercial quality lecithin. Free fatty acids, of
a higher quality than the acid oil obtained from soapstock,
can be obtained directly from the steam distillate in a much
purer form.
It should be noted that the process described here-
in is effective to remove mycotoxins, such as aflatoxin, from
the crude oil. However, where such toxins are present it is
possible that by-products may contain these contaminants.
-18
'75~
Assuming, for the moment, that a certain crude oil
contained relatively high concentrations of low temperature
insolubles (waxes) as well as trace metals and both hydratable
and non-hydratable phospholipids. As a first processing step
the crude oil would be degummed with water. A small amount
of water, typically 1 to 5 percent by weight, would be added
and agitated with the oil. The amount of water should be
sufficient to remove the significant portion of the hydrat-
able compounds~ Afterwards the oil is separated by any
practical means, and centrifuging or settling are common.
~ his step may be carried out at any convenient tem-
perature and robm temperature is often suitable. However,
lower temperatures are useful in order to provide the most
efficient removal of compounds which are not soluble in the
oil at low temperatures, re~erred to generally as "waxes".
It is advantageous therefore where such waxes are present to
complete this step at a slightly lower temperature, and
temperatures in the range of about 5C. to about 20C. are
most suitable.
In order to remove non-hydratable phospholipids and
trace metals such as iron, copper, calcium, magnesium or the
like, an additional pretreatment step is necessary. A small
amount of a suitable degumming reagent, typically less than
one percent (1%) by weight, and water are added to the oil
2~ and agitatedO The reagent may be chosen from many which are
known to the art, such as organic or inorganic acids or their
:
-- 19
anhydrides. Emulsifiers and surfactants are also known to
be useful for this purpose. ~t present, the p~eferred
reagents are maleic, fumaric, citric and phosphoric acia.
The degummed/demetalized oil is then separated from the
heavy phase containing any residual phospholipids and trace
metals.
Oil prepared for bleaching, through the steps set
out above~ or by any other method known to the art, is com-
bined with a small amount of phosphoric acid in aqueous
solution. It is preferred to use a concentrated solution
to reduce the need for later water removal. The amou~t of
phosphoric acid should be enough to form a mixture with at
least two one-hundredths of a percent (0.02%) phosphoric
acid by weight in the oil. Although larger amounts could
lS be used, any concentration higher than about two-tenths of a
percent (0.2~) phosphoric acid would cause a removal problem
and this level therefore represents an upper limit as a
practical matter. The preferred range is from about five
one-hundredths of a percent (0.05~) to about one tenth of a
percent (0.1%) phosphoric acid by weight~
This mixture of oil and phosphoric acid is then
agitated and it is advantageous to raise the temperature
slightly. Temperatures between about 35Co and 40C. are
typically employed advantageously, although at higher temper-
atures, usually above 40C., it is considered necessary tointroduce vacuum to prevent the harmful effects of oxidation
.
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on the oil quality.
At this stage a bleaching agent, such as activated
bleaching earth, Fuller's earth or the like is added in a
suitable amount in order to remove most, but not all, of the
phosphoric acid previously added. The amount of bleaching
agent should be calculated to provide an oil as a final
product with a level of up to three parts per million (3 ppm)
residual phosphorus derived from the phosphoric acid. The
preferred bleaching agent is an activated bleaching clay com-
mercially available under the Tradename Filtrol 105 ~ from
Filtrol Corporation, which has been used advantageously in theExamples which follow. If vacuum has not previously been
introduced, the system should be evacuated prior to heating
the mixture to a temperature suitable for the action of the
chosen bleaching agent and aqitating. Following the action
of the bleaching agent, the bleached oil should be filtered.
To prevent oxidation o~ the oil, the vacuum should not be
broken until the oil has been cooled sufficiently. Alter
natively, the oil could be blanketed with an inert gas such
as nitrogen or carbon dioxide.
The oil bleached in this manner can then be steam
reined/deodorized in a manner known to the art to complete
the proce~sing.
The present invention is shown more clearly in the
following illustrative examples.
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'75~:~
EXAMPLE 1
A high quality corn oil was extracted from corn
germ by the process disclosed in Application No~ 8012909
filed in Great Britain on April 18, 1980, published on
October 28, 1981 as UK Patent Application No. 2,074,1830
The same disclosure recently issued as United States Patent
4,341,713 claiming priority of the British Application. The
corn oil obtained in this manner was uncharacteristically
free of phospholipids and waxes, and was refined by the
process of this invention and by the alkali refining process
of the conventional art for comparison. Certain physical
and chemical properties of this crude oil are listed in
Table 1.
A six kilogram (6.0 Kg) quantity of the crude corn
oil maintained under a vacuum of two millimeters mercury
(~mm Rg) absolute pressure at 40Co was treated with four
one-hundredths of a percent (0.04~) by weight phosphoric acid
in an eighty-five percent (85%) concentration in aqueous solu-
tion and agitated intensely for 15 minutes. Then, one percent
~0 ~1.0%) bleaching earth by weight of the oil, commercially avail-
able from Filtrol Corporation under the Trademark Filtrol 10
and two-tenths of a percent (0.2~) filter aid by weight of the
oil, available from the Johns-Manville Corporation under the
trademark Filtercel ~ were added to this evacuated system.
The system was heated to 120C. and intense agitation continued
for an additional 20 minutes, after which the mixture was
- 22 -
cooled to 80C. and the vacuum was broken with nitrogen. The
bleached oil was filtered off in a Buechner funnel and two
portions of two and three-tenths kilogram (2.3 Kg) each were
measured out.
The first such portion was designated Sample A and
was steam refined-deodorlzed for 90 minutes at 240C. under
a vacuum of two-tenths of a millimeter mercury (0.2mm Hg)
absolute pressure using two percent ~2.0%) sparging steam.
A small amount of citric acid, known to be a useful additive
in alkali refined oils, was added to the second portion,
designated Sample B, in a twenty percent (20%) aqueous solu-
tion in order to yield a feedstock for deodorization having
one hundred parts per million (100 ppm) citric acid. The
sample was then steam refined/deodorized under the same con-
ditions as Sample A. Physical and chemical properties of
Sample A and B are also shown in Table 1.
Comparative samples were prepared by conventional
alkali refining methods in the following manner. A six and
one-tenth kilogram (6.1 Kg) quantity of the same crude corn
oil maintained at 40C. was treated with a ~wo and eight-
tenths of a percent (2.8%) of 16 Baume sodium hydroxide
solution and agitated intensely for 15 minutes. The oil was
then heated to 65C. and stirred for an additional 15 minutes.
Following this the oil was centrifuged at fourteen hundred
and thirty-three (1433~ times the gravitational constant
(9.81 m/sec2) at a rate of nine kilograms per hour (9 Kg/hr)
'ô 5;~,~
to separate the precipatated soaps. All centrifugations
in this and the following examples were carried out under
these conditions unless specifically notedO The oil was
then washed by twice adding and mixing hot dis~illed
water in the amount of ten percent (10~) by weight and
centrifuging each time. Subsequently, the oil was dried at
a temperature of 100C. under a vacuum of two millimeters
mercury (2mm Hg) absolute pressure for 3Q minutes.
The oil was bleached by adding one percent (1.0%)
bleaching earth by weight of the oil, commercially available
from Filtrol Corporation under the Trademark Filtrol ~ 105,
together with two-tenths of a percent (0~2%) filter aid by
weight of the oil, commercially available from the Johns-
Manville Corporation under the Trademark Filtercel ~,
heating the mixture to 120C. under a vacuum of two millimeters
mercury (2mm Hg) absolute pressure and agitating for 20 minutes.
After cooling to 80Co ~ the oil was filtered off in a Buechner
funnel and two portions of two and three-tenths kilogram (2~3
Kg) each were measured out. Sample C was deodorized for 90
minutes at 240C. under a vacuum of two--tenths of a millimeter
of mercury (0.2mm Hg) absolute pressure using one and one half
percent (1.5~) sparging steam. A small amount of citric acid
was added to Sample D in a twenty percent (20%) aqueous solu-
tion in order to yield a feedstock ror deodorizat.on having
one hunderd parts per million (100 ppm) citric acid. The
sample was then deodorized under the same conditions as
- 24 -
5~
Sample C. Physical and chemical properties o Samples C and
D are also given in Table 1.
TABLE 1
Phos- Toco-
Free Fatty Color phorus Iron pherols
Sample Acid,% Yellow Red ppm ppm %
Crude Corn Oil 1.2 42 9.1 0.0 1.3 0.164
Sample A 0.015 2 0.5 2.3 0.1 0.109
Sample B 0.015 2 0.5 2.8 0.1 0.083
Sample C 0.010 1 0.1 1.0 0.1 0.094
Sample D 0.010 1 0.1 1.1 0.1 0.100
To assess the stability of the samples produced,
the oils were subjected to color reversion and flavor
stability tests.
The color reversion test consisted of storage in
the dark at ambient temperature with unlimited air space for
eight weeks. Color measurements were performed according to
AOCS Official Method Cd 13b-45. The color reversion data for
each sample are given in Table 2. Since the reversion of
color is believed to be a result of oxidative changes in the
oil, peroxide values were also measured according to the AOCS
Official Method Cd 8-53 at the time of each color determina-
tion. This data is also given in Table 2.
- 25 -
75~
r~ o Lr ~r
o ~ o
Q.
o o
GJ
.,
X ~ ~~D OU~
o~
c~~ ta o ~ ~ ~~
R~
O ~ e
~ a.). . . . .
U~~J p~O O
~0 0
0 ~_
'-I aJ
m x
~ O ~1 . . . .
E~ m~ ~ o o ~ o
P~
a.J . . . O
U~ ~; O O O O O
O O
t_) ~ ~ ~ ~ ~ ~ o
a~
":5
X
o o ~ ,~
a ~ . . . . .
U~ ~;O O O O O
O O
~C X ,Y ~ X
3 3 ~ 3 ~
H r-l ~ ~ 15~ CO
-- 26 --
~'75~:~
Flavor stability tests were conducted as
follows: Samples were stored in the dark at 35C. with ten
percent (10%) air head space and flavor determinations were
made by a trained panel after two (2), five (5) and twelve
(12) months. Each sample was scored for flavor strength on
a scale from 1 to 9 with 1 being completely flavorless and 9
extremely strong. The results of these tests are given in
Table 3.
TABLE 3
Sample A Sample B Sample C Sample D
Storage
Period
Initially 2.0 2.1 1.9 2.1
2 Months2.8 2.8 4.8* 3.8
5 Months2.4 3.4 4.7* 2.8
12 Months4.6 4.3 Unacceptable* 5.5
* Panel judged flavor significantly stronger with a 99%
confidence level.
EXAMPLE 2
Crude, expelled corn oil having appreciable amounts
of impurities such as free fatty acids, phospholipids, waxes,
trace metals and proteinaceous matter was prepared by the
common commercial expelling process. In this process crude
oil is recovered by subjecting dry corn germ, typically con-
- 27 -
5~
taining from forty-three percent (43%) to forty-five percent
(45%) oil and moisture in the amount of one and one-half
percent (1.5~) to two percent (2.0~) by weight, to mechanical
pressure in a screw press. Physical and chemical properties
for this crude oil are given in Table 4.
A thirteen and one-tenth kilogram (13.1 Kg) quan-
tity of the crude corn oil was mixed with three percent
(3.0%) by weight of distilled water and heated to 60C. The
oil was held at this temperature and intensely agitated for
15 minutes. Precipitating gums were separated by centrifuga-
tion.
The degummed oil thus obtained was treated with
two-tenths of one~percent (0.2~) by weight phosphoric acid
in an eighty-five percent (85%) concentration in aqueous
solution. The oil was intensely agitated at a temperature
of 40C. for a period of 15 minutes. Then, three percent
(3.0%) ~y weight distilled water was added and the temperature
was raised to 60C. and agitated ~or 15 minutes. The oil was
then centrifuged to remove the residual yums and metal
complexes.
The first portion of five and two~tenths kilogram
(5.2 Kg) of the degummed, demetalized oil was treated with
one-tenth of one percent (0.1%) phosphoric acid in an eighty-
five percent (85%) concentration in aaueous solution~ The
oil was then stirred for 15 minutes at 40C. under a vacuum
- 28 -
8'i~S~
of two millimeters mercury (2mm Hg) absolute pressure. The
same bleaching earth and filter aid described in Example 1
were then added in the amount of three percent (3.0%)
bleaching earth by weight of the oil and six-tenths of one
percent (0.6~) filter aid by weight of the oil. This mix-
ture was heated to 120C. and aqitated for 20 minutes. The
oil was cooled to 90C., the vacuum was broken with nitroyen
and the oil was filtered off in a Buechner funnel.
Sample E and Sample F, each containing two and
three-tenths kilogram (2.3 Kg) were measured out from the
bleached oil obtained in this manner. As in Example 1,
citric acid in twenty percent (20~) aqueous solution was
added to Sample~F to provide one hundred parts per million
(100 ppm) citric acid in the feedstock for deodorization.
Both samples were then steam refined-deodorized for 90
minutes at 240C. under a vacuum of two-tenths of a milli-
meter of mercury (0.2mm Hg) absolute pressure using two
percent (2.0%) sparging steam. Physical and chemical proper-
ties for ~these samples are given in Table 4.
The second portion of six and t~o-tenths kilogram
(6.2 Kg) of the degummed, demetalized oil was reacted with
a five and four-tenths of one percent (5.4%) of 16 ~aume
sodium hydroxide solution and agitated intensely at 40C.
for 15 minutes~ The oil was then heated to 65C. and
stirred for 15 minutes. Soapstock produced was separated
from the oil by centrifugation. The oil was then washed by
:
- 2~ -
twice adding and mixing hot distilled water in the a~ount of
ten percent (10~) by weight and centrifuging each time.
Subsequently, the oil was dried at a temperature of 100C.
under a vacuum of two millimeters mercury (2mm Hg) abso-
lute pressure for 30 minutes.
The oil was bleached by adding two percent (2.0%)
bleaching earth by weight of the oil, and four-tenths of one
percent (0.4%) of the filter aid, by weight of the oil, used
in Example 1. The mixture was heated to 120C. under a vacuum
of two millimeters of mercury (2mm Hg) absolute pressure and
agitated for 20 minutes. The mixture was then cooled to 90C.,
the vacuum was broken with nitrogen and the oil was filtered
off with a Buechner funnel. Sample G and Sample H, each con-
taining two and three-tenths kilogram (2.3 Kg), were measured
out from the oil obtained in this manner. As in Example 1,
citric acid in a twenty percent (20%) aqueous solution was
added to Sample H to provide one hundred parts per million
(100 ppm) citric acid in the feedstock for deodorization.
Both samples were then deodorized for 90 minutes at 240C.
under a vacuum of two-tenths of a millimeter of mercury
(0.2mm Hg) absolute pressure using two percent (2.0~) sparging
steam. Physical and chemical properties for these samples
are given in Table 4.
- 30 -
:~87~
TABLE 4
Sample Free Fatty Color Phosphorus Iron Tocopherols
Acid,% Yellow Redppm ppm %
Crude
Corn Oil 1.8 440.0 1.4 0.144
Sample E 0.020 6 1.0 1.9 0.1 - 0.070
Sample F 00023 6 1DO 2~3 Oal 00096
Sample G 0.010 3 0.5 1.6 0.1 0.098
Sample H 0.010 3 0.5 1.0 0.0 0.091
Following the methods used in Example 1, the
samples produced were subjected to color reversion and flavor
stability tests. The resulting data are shown in Table 5 and
Table 6.
'7~
~1 a
x ~ o
:Co
s~ ,a I o o ~ o
P~
~ ~ c~ o
o o o o o o
O O
C~ ~1
X 3
O ~ 1 1 o o
a
aJP~
U~o C~; O o ,i ~1 ~ o
O ~
O oln ~r ~o
U~
a~
~3
~ ~ a
m x 3 1
F~ O r~
O O O O
P~
O o
Q~. . .
O
~1 3
C)
~O ~ I` 00
a~
X ~ I ~ ~ O
0~
CL1 h ~a O O ~1
Pl
a~ ~ o c~ r~ o ~D
3 ~ s=, o ~ ,_~
O O
~o co r~
~ ~ ~ x x ~y
,~ a) a) aJ a~ a~
~: 3 ~ ~Z 3
H ~1 ~ 1~ ifl ~
-- 32
TABLE 6
Sample ESample FSample G Sample H
Storage
Period
Initially 2.1 2.2 2~8 2.6
2 Months 4.4 3.2 5.7* 3.7
5 Months 3.9 4.2 5~6* 4.1
12 Months 5.1 4.3 Unacceptable* 5.0
*Panel judged flavor signiicantly stronger with a 99
confidence level.
EXAMPLE 3
A two thousand two hundred and sixty kilogram
(2260 Kg) quantity of regular production crude expelled
corn oil was placed into 2 stainless steel kettle equipped
with a two-propeller stirrer. One hundred and thirteen
kilograms (113 Kg) water, amounting to five percent (5.0~)
by weight, was added to the oil and the mixture was agitated
at two hundred and fifty revolutions per minute (250 rpm)
at ambient temperature (approximately 27C.) for 30 minutes.
~ The precipating gums were separated in a Westphalia ~
centrifuge operating at seventy-eight hundred revolutions
per minute (7800 rpm) t with an oil flow rate of four and
one-half kilograms per minute (4.5 Kg/ minute). The de-
gummed oil obtained was deaerated and dried under a vacuum
of eighty millimeters or mercury ~80mm Hg) absolute
- 33 -
5~
pressure at a temperature of 40C. with intense agitation
for 70 minutes.
To this oil, two and six one-hundredths kilogram
(2.06 Kg) food grade phosphoric acid, amounting to one tenth
of one percent (0.1~) by weight, in an eighty-five percent
(85%) concentration in aqueous solution was added and the
mixture was further agitated under vacuum for another 30
minutes. A two hundred and fifty liter (250~,) portion of
the oil was pumped lnto a slurrv kettle where it was mixed
with sixty two kilograms (62 Kg), representing three percent
(3.0~) by weight of the total oil, bleaching earth (Filtrol
105 as described in Example l) and twelve and one-half ]cilo-
gram (12.5 Kg)~ representing six-tenths of a percent (0.6~)
by weight of the total oil, filter aid commercially available
from the Johns-Manville Corporation under the Trademark Hyflo
Super-Cel ~. The mixture in the slurry kettle was agitated
intensely for 5 minutes, and was then reintroduced into the
original kettle, still under vacuum. The mixture was heated to
120C. and agitated at one hundred revolutions per minute (100
rpm) for 30 minutes. The mixture was then cooled to 60C. and
held under reduced pressure of one hundred millimeters of
mercury (lOOmm Hg) absolute pressure until filtration was
completed. The filter press was then blown with nitrogen to
recover excess oil.
2, To produce samples which were both citrated and
non-citrated, citric acid in the form of a twenty percent
- 34 -
5~
(20~) aqueous solution was introduced into a quantity of
the oil, designated as Sample J. Citric acid was 2dded into
the final deodorization stage at the rate of one l~illiliter
per minute tl ml/min) representing a proportion of citric
acid to the oil of fifty parts per million (50 ppm)O The
remaining oil was not treated with citric acid and was
designated as Sample R.
Both samples were steam refined-deodorized ln a
continuous pilot plant deodorizer unit at an oil flow rate
of two hundred and seventy-four kilograms per hour
(274 Kg/hr) at a temperature of 227C. under a vacuum of one
to two millimeters of mercury tl-2mm Hg) absolute pressure
using three percent (3.0~) sparging steam~
Physical and chemical characteristics of the
citrated and non-citrated oils are given in Table 7. Color
reversion and peroxide value data for the oils obtained in
the same manner as described in Example l are given in Table
8, and flavor stability data are given in Table 5.
~LE 7
_
Total
Free Fatty Color Phosphoms Iron W~ Test (GLC)
Acid,% Yellcw Red ppm ppm ~ hrs. ppm
Sample J 0o028 6 0.9 0.9 0.1 5.0 74 215
Sample K 0O034 6 0.9 0.9 0.1 8.0 74 4.7
- 35 -
~3'7~ ~
TABLE 8
Sample J Sample K
Color Peroxide Color Peroxide
Yellow Red Value Yellow RedValue
Initially 60.9 -- 6 0.9
2 Weeks 7 0.2~0.5 9 0.5 0.5
4 Weeks 9 1.20.5 11 1.6 0.9
6 Weeks12 1.02.0 15 1~1 3.3
8 Weeks12 1.11.2 17 1.2 2.2
10 Weeks13 1.20.9 16 2.U 1.4
TABLE 9
Storage
Period Sample J Sample K
Initially 4.0 4.1
2 Months 3.7 3.2
5 Months 4.5 5.1
8 Months 5.4 5.4
FXAMPLE 4
Samples of typical crude soybean oil were refined
by the process of this invention and by the alkali refining
process of the conventional art for comparison. Certain
physical and chemical properties of the oill at each stage
of both refining processes are given in Table 10.
~ fourteen kilogram (14 Kg) quantity of crude soy-
bean oil was heated to 40C. in a glass container, then three
~ 36 -
75~
percent (3.0~) by weight of distilled water was added and the
oil was agitated intensely for 20 minutes. The temperature
was raised to 60C. and a slower agitation continued for
another 20 minutes. The oil was then centrifuyed to
separate the hydrated phosphatides.
The oil thus obtained was treated with two-tenths
of a percent ~0.2~) phosphoric acid in an eighty~~ive per-
cent (85~) concentration in aqueous solution and agitated
intensely for 15 minutes at a temperature 40C. under a
lQ nitrogen atmosphere. Distilled water, in the amount of
three percent (3.0%) by weight, was then added to the oil.
The temperature was increased to 60C. and a slower agita-
tion continued for another 20 minutes. The oil was then
centrifuged under the same conditions as above to separa~e
the oil from residual phospllatides and gums.
A five and three-tenths kilogram (5.3 Kg) portion
of the twice degummed oil was treated with three one-
hundredths of a percent (0.03%) phosphoric acid in an eighty-
five percent (85~) concentration in aqueous solution and
stirred at 40C. under a vacuum of two millimeters of mercury
(2mm Hg) absolute pressure for lS minutes.
Then, one percent (1.0~) bleaching earth, by weight
of the oil, commercially available from Filtrol Corporation
under the Trademark Filtrol 10 ~ , and two~tenths of a
percent (0.2%) filter aid, by weight of the oil, commercially
available from the Johns-Manville Corporation under the Trade-
- 37 -
~ 8~
mark Filtercel ~ were added and the mixture, while still
under vacuum, was heated to 120C~ and intensely agitated.
After twenty minutes of such continued treatment, the mix-
- ture was cooled to 80C., the vacuum was broken with nitrogen
and the oil was filtered off in a Buechner ~unnel.
A small amount of citric acid in a fifteen percent
(15~) a~ueous solution was added to yield one hundred parts
per million (100 ppm) citric acid in the bleached oil, and
the oil was then steam refined-deodorized for 90 minutes
~t 240C. under a vacuum of two-tenths of a millimeter of
mercury (0.2mm Hg) absolute pressure using one and seven~
tenths percent (1.7%) sparging steam. The oil obtained in
this manner was designated Sample L.
A comparative sample was prepared by conventional
alkali refining methods in the following manner. A six and
four-tenths kilogram (6.4 Kg) quantity of the same twice
deyummed oil maintained at 40C. was treated with four and
fifty-six one-hundreths of a percent (4.56~) of 16 Baume
sQdium hydroxide solution and was agitated intensely under
a nitrogen atmosphere for 15 minutesO The temperature was
increased to 65C. and a slower stirring continued for another
15 minutes. The oil was then centrifuged to separate the
precipitated soaps. ~ollowing this, the oil was washed by
twice adding and mixing hot distilled water in the amount
~5 of ten percent (10%) by weight and centri~uging each timeO
Subsequently, the oil was dried at a temperature or 105C.
~ 38 -
~ '3~
under a vacuum of two millimeters of mercury (2~n Hg) absolute
pressure for 30 minutes~
The oil was bleached by adding one percent (1~0%) by
weight of the same bleaching earth and two-tenths of a percent
(0.2%) by weight of the same filter aid employed above, heating
the mixture to 120C. under a vacuum of two millimeters mercury
(2mm Hg) absolute pressure and agitating or 20 minutes.
After cooling to 80C., the oil was filtered off in a Buechner
funnel. A small amount of citric acid in a fiEteen percent
(15~) aqueous solution was added to yield one hundred parts
per million (100 ppm) citric acid in the bleached oil. The
oil was then deodorized or 90 minutes at 250C. under a
vacuum of two-tenths of a millimeter of mercury (0.2mm Hg)
absolute pressure using one and one-half percent (1.5%)
sparging steam. The oil obtained in this manner was desig~
nated Sample M.
- 39 -
TABLE 10
Color Free Fatty Phosphorus Iron
Processing Yellow Red Acids, ~ppm ppm
Stage
5Initial Steps
Crude Oil 7816.1 0.54380.0 108
Water
Degummed Oil 7510.8 0.158 .53O4 0.5
Acid Redegummed
Oil 76lOoO 0~15520~0 0~2
Physical Process
Bleached Oil 151~7 0~18 2.3 0.1
Steam-Refined
Deodorized
(Sample L) 10.3 0.0152.3 0.1
Alkali Process
Alkali Treated 40 10.0 0.01
Alkali Treated
- ~leached 101.0 0.05 0.4 0.1
Alkali Treated
- Deodorized
(Sample M) 1 0.1 0.010 O~A 0.l
The samples obtained in the above manner were then
tested for flavor stability. The samples were sealed in
clear eight ounce (8 oz.) glass bottles with ten percent
(10%) air headspace, and aged under irradiation and dark
storage conditions. The samples subjected to irradiation
were stored for three (3) weeks in a light cabinet having a
continuous light exposure equivalent to sixty-five (65) foot
candles at a constant temperature of 35C. The samples
subjected to dark storage were kept in a light-proof cabine~
40 -
~'7S~
for six (6) months at a constant temperature of 35C.
Following the method described in Example 1, ~lavor evalua-
tions on a scale of 1 to 9 were made by a trained panel. The
results are reported in Table 11.
TABLE 11
Sample L Sample M
Initial 2.3 2.6
Light Storage
1 Week 4.6 4.8
2 Weeks 4.9 ~ 4.8
3 WeeXs 5.1 5.1
Dark Storage
2 Months 2O7 3.6*
4 Months 3.2 3.5
6 Months 4.1 4.7
*Panel judged flavor significantly stronger with a 99
confidence level.
E XAMP LE 5
Commercial Canadian rapeseed oil is produced from
rapeseed varieties which are typically low in erucic acid and
glucosinolate. This oil is commercially available as a water-
degummed crude which contains a maximum of two hundred parts
per million (200 ppm) residual phosphorus and no more than
five percent (5.0~) erucic acid. As described below, a
- 41 -
'i'5~
sample of this oil was refined in the laboratory according to
the process of the present invention. An additional sample
was prepared by the alkali refining process of the conven-
tional art for comparison. Certain physical and chemical
properties of this commercially available oil are listed in
Table 12.
A ten kilogram (10 Kg) sample-of this Canadian com-
mercial grade crude rapeseed oil was placed in a metal con-
tainer. With the temperature held constant at 25C., maleic
acid in aqueous solution in the amoun~ of two-hundredths of
a percent (0.02~) by weight of the oil was added and the
mixture was stirred for ten minutes. Distilled water, in the
amount of three percent (3.0~) by weight or the oil, was
added and the mixture was agitated for an additional twenty
(20) minutes. The mixture was then centrifuged to separate
the oil from the hydrated phospholipids.
A three and three-tenths kilogram (3.3 Kg) portion
of the rapeseed oil degummed in this manne~ was bleached ac-
cording to the further teachings of the present invention.
The oil was maintained under a vacuum of two millimeters of
mercury (2mm Hg) absolute pressure at ~0C. and was treated
with one-tenth of one percent (0.1~) phosphoric acid by
weight of the oil in an eighty-five percent (85%) concenira-
tion in aqueous solution and agitated intensely for 10 minutes.
Then, three percent (3~0~) bleaching earth, by weight of ~he
oil, commercially available from Filtrol Corporation under the
- ~2 -
8~75~L~
Trademark Filtrol 10 ~ , and six-tenths of a percent (0.6%)
filter aid, by weight of the oil, commercially available from
~ohns-Manville Corporation under the Trademark Filtercel ~,
were added to this evacuated system. The system was heated to
120C. with intense agitation. After 20 minutes at this tem-
perature, the mixture was cooled to 80C., agitation ~as
discontinued and the vacuum was broken with nitrogen. The
bleached oil was then filtered off in a ~uechner funnel.
A two and four-tenths kilogram (2.4 Kg) portion
of the bleached oil thus obtained was then steam refined-
deodorized. The bleached oil was ~irst treated with fift~
parts per million (50 ppm) citric acid, added in a twenty
percent (20%) aqueous solution. Subsequently, the oil was
steam refined-deodorized in a five liter (5~ flask for 90
lS minutes at 2~0C. under a vacuum of two-tenths of a millimeter
of mercury (0.2mm Hg) absolute pressure, using two percent
(2.0%) sparging steam. The rapeseed oil physically refined
in this manner was designated Sample N. Certain physical and
chemical properties of this oil, at various process stages,
are shown in Table 12.
A comparative sample was processed by the conven-
tional alkali refining method in the following manner. A five
and seven-tenths kilogram quantity ~5.7 Kg) of the rapeseed
oil degumnted with maleic acid as described above was treated
with one and three-tenths percent (1.3~) of 14 Baume sodium
hydroxide solution and agitated intensely at 25C. for 15
- 43 -
5~
minutes. Next, the temperature was raised to 65C. and the oil
was stirred slowly for an additional 15 minutes. Afterwards,
the precipitating soaps were separated from the oil by centri-
fugation. The oil was then washed twice by adding and mixing
hot water in the amount of ten percent (10%) by weight and
separating the water each time by centrifugation. Following
thls, the oil was dried at a temperature of 60C. under a
vacuum of two millimeters mercury (2mm Hg) absolute pressure
for 15 minutes.
A three and six-tenths kilogram (3.6 Kg) quantity
of the oil refined with alkali in this manner was bleached by
adding two perc`ent (2.0~) bleaching earth, by weight of the
oil, commercially available from the Filtrol Corporation
under the Trademark Filtrol ~ 105, together with four-tenths
of a percent (0.~) filter aid, by weight of the oil, commer-
cially available from Johns~Manville Corporation under the
Trademark Filterce ~ . The mixture was then heated to
120C. under a vacuum o~ two millimeters mercury (2mm Hg)
absolute pressure and agitated for 20 minutes. The mixture
was then cooled to 80C., the vacuum was broken with nitrogen
and the oil was filtered in a Buechner funnel.
A sample o~ two and four-tenths kilogram (2.~ Kg) of
this oil was measured out and fifty parts per million (50 ppm)
citric acid in a twenty percent (20~) aqueous solution was
added. The oil was deodorized for 90 minutes at 2~0C. un~er
a vacuum of two-tenths of a millimeter of mercury (0~2mm Hg)
- 44 -
t~
absolute pressure using one and five-tenths percent (1.5~)
sparging steam. The finished alkali refined oil produced in
this manner was designated Sample 0. Certain physical and
chemical properties and properties of this oil, at various
process stages are also shown in Table 12.
TABLE 12
Color
(1" Cell) Free Fatty Phosphorous Iron
Processing Stage Yellow Red Acid, % ppm ppm
Initial Steps
Startinq commercial 73 5.7 0.57 163 1.6
crude oil,
Oil degummed with36 `5.8 0.49 6 0.3
maleic acid and
water
Physical Process
Bleached oil 7 Q.5 0.50 0.0 0.0
Steam refined- 3* 0.2* 0.01 - 0.0
deodorized oil
~Sample N)
Alkali Process
Alkali refined oil 53 4.5 0.02 5.2 0.0
Bleached oil 9 0.8 0.10 0.9 0.0
Deodorized oil 2* 0.3* 0.01 - 0.0
(Sample 0)
*Color measured in 5 1/4 inch cell
- 45 -
'751~
To assess the stability of the finished rapeseed
oils produced, Samples N and 0 were subjected to flavor
stability tests. The oils were sealed in clear eight ounce
(8 oz.) glass bottles with ten percent (10%) air headspace
and aged under irradiation and dark storage conditions. The
irradiated samples were stored for three ~3) weeks in a light
cabinet having a continuous light exposure equivalent to sixty
five (65) foot candles at a constant temperature of 35C. The
samples subjected to dark storage were kept in a light-proof
cabinet for eight (8) weeks at a constant temperature of 30C.
Flavor evaluations were performed by a trained panel. Each
sample was scored for flavor strength on a scale from one (1)
to nine (9) with one (1) being completely flavorless and nine
(9) extremely strong. The results are shown in Table 13.
- 46 -
~'7~
. TABLE 13
Storage PeriodSample N Sample O
Initial 2.6 2.9
Light Storage
. 1 week 4.6 3.g
2 weeks 4.6 5.2
3 weeks 5.1 4.9
Dark Storage
2 weeks 2.5 2.9
4 weeks 3.0 3.2
6 weeks 2.9 3.9*
8 weeks 3.7 3.7
* Panel judged flavor significantly stronger with
a 99% confidence level
EXAMPLE 6
A sample of commercially available crude peanut oil
was divided into two portions, one of which was refined by
the process of this invention and the other by conventional
alkali refining for comparison. Certain physical and
zo chemical properties of the crude oil and samples obtained at
various stages of each refining process are listed in Table
14.
A ten kilogram (10 Kg) sample of crude peanut oil
was mixed with two percent (2.0~) distilled water, by weight of
- 47 -
~8~
the oil, and agitated intensel~ for 30 minutes at a temperature
o 25C. The oil was then centrifuged to separate the hydrated
phospholipids.
Two and eight-tenths kilograms (2.8 Kg) of the
peanut oil de~ummed in this manner was treated with two-
hundredths of a percent (0.02~) phosphoric acid~ by weight
of the oil, in an eighty-five percent (85~) concentration in
aqueous solution and agitated intensely for 15 minutes at a
temperature of 40C. under atmospheric pressure. Then, five-
tenths of a percent (0.5~) Filtrol 10 ~ bleaching earth,by weight of the oil, and one-tenth of a percent (0.1~) Fil-
tercel ~ filter aid, by weight of the oil, both described in
previous examples, were added and the mi~ture was agitated
under a vacuum of two millimeters of mercury (2mm Hg) absolute
pressure while the temperature was raised to 110C. After 20
minutes of intense agitation under these conditions the mix-
ture was cooled to 90C., the vacuum was broken with nitrogen
and the oil was filtered off in a Buechner funnel.
A two and four-tenths kilogram (2.4 Ky) sample of the
bleached oil was treated with thirty parts per million (30 ppm)
citric acid in a twenty percent (20~) a~ueous solution and the
oil was then steam refined-deodorized for 90 minutes at 240C.
under a vacuum of two-tenths of a millimeter of mercury
(0.2mm Hg) absolute pressure using two percent (2.0~) sparging
steam. The oil obtained in this manner was designated Sample P.
- 48 -
'7S.L~
A comparitive sample was prepared by the conven-
tional alkali refining method in the following manner. A two
and eight-tenths kilogram (2.8 Kg) quantity of oil which had
previously been degummed with water was treated with one and
two-tenths of a percent (1.2%) 1~ Baume sodium hydroxide
solution, by weight of the oil, and agitated intensely at 25C.
for 15 minutesO The temperature was then raised to 65C~ and
the oil was stirred slowly for an additional 15 minutes. The
oil was centrifuged to separate the precipitated soaps. This
was followed by twice washing the oil with hot distilled water
in the amount of ten percent (10%) by weight and centrifuging
each time. Finally, the oil was dried at a temperature of
60C. under a vacuum of two millimeters of mercury (2mm Hg)
absolute pressure for 15 minu~es.
Bleaching of the oil was performed by adding five-
tenths of a percent (0.5%) of Filtrol 10 ~ bleaching earth
together with one-tenth o a percent (0.1%) of Filtercel ~
type filter aid, heating the mixture to 110C. under a vacuum
of two millimeters mercury (2mm Hg) absolute pressure and
agitating for 20 minutes. After cooling the mixture to 90C.,
the vacuum was broken with nitrogen and the oil was filtered
in a Buechner funnel.
A two and four-tenths kilogram ~2.4 Kg) sample of
the bleached oil was treated with thirty parts per million (30
ppm) citric acid in a twenty precent (20~) aqueous solution,
and deodorized for 60 minutes at 240C. under a vacuum of two-
:
- 49 -
~ ~'7S~
tenths of a millimeter of mercury (0.2mm Hg) absolute pressure
using one and one-half percent (1.5%) sparging steam. The oil
obtained in this manner was designated Sample R.
TABLE 14
Color
(S 1/4" Cell) Free Fatty Phosphorus Iron
Processing Stage Yellow Red Acid, ~ ppm ppm
Initial Step
Starting crude oil 50 3.5 0.35 246 0.5
Water degummed oil 50 3.5 0.08 - -
Physical Process
Bleached oil 2.9 0.5 0.063 2 0.0
Steam Refined- 0.7 0.2 0.017 2 -
Deodorized oil
(Sample P)
Alkali Process
Bleached oil 0.8 0.1 0.015 0.3 0.0
Deodorized oil 0.7 0.1 0.010 0
(Sample R)
~oth samples were tested for color reversion and de-
velopment of peroxides. The color reversion test consisted
of storage in the dark at 25C. with unlimited air headspace
for 6 weeks. Color and peroxide measurements were performed
according to AOCS Official Methods, Cd 13b 45 and Cd 8-53
respectively, The results are given in Table 15.
- 50 -
'75~g~
TABLE 15
Sample P Sample R
Color Peroxide Color Peroxide
Yellow Red Value Yellow Red Value
S Initially 0.1 ~.2 0.0 0.7 0.1 0.0
2 Weeks 1.3 0 3 0.7 2.1 0.5 1.5
4 Weeks 1.9 0~4 1.0 2.5 0.6 4.0
6 Weeks 208 0.8 0.8 3.1 0.8 7.8
EXAMPLE 7
_ . .
Crude, "non-break" safflowçr oil, which is available
commercially, typically has already been degummed with water.
The residual level of phospholipids in such oil is sufficiently
low that the oil may be refined by the process of the present
invention without any additional pretreatment. Cer~ain
physical and chemical characteristics of this crude safflower
oil and samples obtained at various stages of each reflning
process are listed in Table 16. A sample of such commercially
available oil was divided into two portions, one of which was
refined by the process of this invention and the other by
conventional alkali refining for comparison.
A three kilogram (3 Kg) sample of crude safflower
oil was treated with eight one-hundredths of a percent (0.08~)
phosphoric acid in an eighty-five percent (85%) concentration
in aqueous solution and stirred at 25C~ under air for 10
mlnutes. Then, two percent (2.0%) Filtrol 105TM bleaching
- 51 -
'75~L~
earth, by weight of the oil, and fo~r-tenths of a percent
(0.4~) Filtercel ~ filter aid, by weight of the oil, both
described previously, were added and the mixture was heated
to 110C. with intense ayitation under a vacuum of two milli-
meters of mercury (2mm Hg) absolute pressure. After 20
minutes of such treatment, the mixture was cooled to ~0C.,
the vacuum was broken with nitrogen and the oil was filtered
in a Buechner funnel.
~ sample of two and four-tenths kilogram (2.4 Kg) of
the bleached oil was measured out and treated with thirty parts
per million (30 ppm) of citric acid in a twenty percent (20~)
aqueous solution. Following this, the oil was steam refined-
deodorized for 90 minutes at 240C. under a vacuum of two-tenths
of a millimeter of mercury (0.2mm Hg) absolute pressure using
two percent (2.0%) sparging steamO The oil obtained in this
manner was designated Sample S.
A comparative sample was prepared by the conventional
alkali refining method in the following manner~ A four and
seven-tenths kilogram (4.7 Rg) quantity of crude safflower oil
was treated with four percent (4.0~) of 14 Baume sodium hydro-
xide solution and was agitated intensely at 25C. for 15
minutes. Then, the temperature was increased to 65C. and a
slower stirring was continued for another 15 minutes. The oil
was then centrifuged to remove soaps. This was followed by
twice washing the oil with hot distilled water in the amount
of ten percent (10%) by weight and centrifuging each timeO
- S2 -
'7~
After the second washina, the oil was dried Lor 15 minutes
at a temperature of 60C. under a vacuum of two millimeters
of mercury (2mm Hg) absolute pressure.
Bleaching of the oil was performed by adding one
and one-half percent (105~) Filtrol 10 ~ bleaching earth,
by weight of the oil, and three-tenths of a percent (0.3%)
Filtercel ~ filter aid, by weight of the oil, and heating the
mixture to 110C. under a vacuum of 20 minutes. After cooling
the mixture t~o 80C., the vacuum was broken with nitrogen and
the oil was flltered in a Buechner funnel.
A small amount of citric acid in a twenty percent
(20%) aqueous solution was added to yield thirty parts per
million (30 ppm) citric acid in the bleached oil. Ne~t, a two
and four-tenths kilogram (2.4 ~g) sample of the oil was deodor-
ized for 60 minutes at 240C~ under a vacuum of two-tenths of a
millimeter of mercury (0.2mm Hg) absolute pressure using one
and one-half percent (1.5%) sparging steam. The oil obtained
in this manner was designated Sample T.
- 53 -
~PI~'75-~
TABLE 16
Color
(5 1/4" Cell) Free Fatty Phosphorus Iron
_ ocessin~ Stage Yellow Red Acid, ~ ppm ppm
Crude, "non- 35 4.1 0.30 53 0.1
break" commer-
cial Safflower
oil
Physical Process
Bleached oil 4.1 0.6 0.29 3.0 0.1
Steam Refined- l o 9 0 ~ 2 0.015 3.0
Deodorized oil
(Sample S)
Alkali Process
.
Alkali Refined 2.2 0.3 0.022 1.0 0.2
and Bleached oil
Deodorized oil 0.9 0.1 0.010 1.0
(Sample T~
Both samples were then subjected to color reversion
test and peroxides measurements by the methods previously
described. The results are listed in Table 17.
TABLE 17
Sample S Sample T
Color Peroxide Color Peroxide
. Yellow Red Value Yellow Red Value
Initially 1.9 0.2 0.0 0.9 0.1 0.0
2 Weeks 2.4 0.4 2.4 1.3 002 2.4
4 Weeks 2.4 0.4 7.6 1.9 0.2 7.8
6 Weeks 2~2 0.318.0 1.7 0.2 17.8
8 Weeks 2.0 0.325~8 1~6 0~2 25~9
- 54 -
~3'75~
Other features, advantages and specific embodi-
ments of this invention will become readily apparent to
those exercising ordinary skill in the art after reading
the foregoing disclosures. These specific embodiments are
within the scope of the claimed subject matter unless other-
wise expressly indicated to the contrary. Moreover, while
specific embodiments o this invention have been described
in considerable detail, variations and modifications of
these embodiments can be effected without departing from
the spirit and scope of this invention as disclosed and
claimed.
8/20/82
RCB/SV/9A-3
