CA1187511A - Refining of oil and product thereof - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

The present invention provides a refined edible oil which has good oxidative, flavor and cold-test stabili-ties, and which will retain such characteristics in storage without the necessity for stabilizing additives. In addi-tion, the present invention provides a method for the produc-tion of such a refined oil which is characterized both by its ability to refine oils with impurities which had previously prevented acceptable processing by physical refining methods and further by its ability to recover economically valuable impurities and by-products.

Description

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 :, 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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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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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 :

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 ~'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).

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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 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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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 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 ~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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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.

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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 :

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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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 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 5~

Sample C. Physical and chemical properties o Samples C and D are also given in 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.

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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.

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.

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-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 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.

:~87~

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 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 ~

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.

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 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 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 ~3'7~ ~

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 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 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-~ 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.

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~

~'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.

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.

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 '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 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) 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.

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 '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.

~'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 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 ~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.

'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-:

~ ~'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.

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.

'75~g~

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 _ . .

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 '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

'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.

~PI~'75-~

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.

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 ~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.

Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the refining 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 oil obtained in step (a)(iii) by i) combining said oil with a small amount of suitable degumming reagent known to the art to form a mixture, ii) agitating said mixture, iii) combining the mixture with a small amount of water, iv) agitating the 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%) phos-phoric 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 de-rived from the phosphoric acid added in (c) (i), iv) raising the temperature of the mixture of step (c)(iii) under vacuum to a tem-perature suitable for the action of the chosen bleaching agent and maintaining said temperature 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).

2. A process for the refining of crude vegetable oils to provide a product having good oxidative, flavor and cold-test stabilities, comprising steps of:

(a) degumming the crude oil by i) combining 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 phosphoric acid in aqueous solution so as to form a mixture with at least two one-hundredths of a percent (0.02%) phos-phoric 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 (b)(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 acid added in (b)(i), iv) raising the temperature of the mixture of step (b)(iii) under vacuum to a tem-perature 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).

3. A process for the refining of crude vegetable oils to provide a product having good oxidative, flavor and cold-test stabilities, comprising the steps of:

(a) degumming/demetalizing the crude oil 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 the mixture, v) separating the oil from the water and 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 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 tem-perature 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).

4. A process for the refining of crude vegetable oils to provide a product having good oxidative, flavor and cold-test stabilities, comprising the steps of:

(a) bleaching the crude oil 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 (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 phosphorus 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 temperature while agitating 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).

5. The process of claim 1, 2 or 3 in which step (a) is carried out at a temperature between 5°C. and 20°C.

6. The process of claim 1, 2 or 3 in which the bleaching step is carried out at a temperature between 90°C. and 120°C.

7. The process of claim 1, 2 or 3 in which the amount of phosphoric acid added in the bleaching step is sufficient to form a mixture with from two one-hundredths of a percent (0.02%) to two tenths of a percent (0.2%) phosphoric acid by weight.

8. The process of claim 1, 2 or 3 in which the amount of phosphoric acid added in the bleaching step is sufficient to form a mixture with from three one-hundredths of a percent (0.03%) to one tenth of a percent (001%) phosphoric acid by weight.

9. An oil having good oxidative, flavor and cold-test stabilities, produced by the process of claim 1.

10. An oil having good oxidative, flavor and cold-test stabilities, produced by the process of claim 2.

11. An oil having good oxidative, flavor and cold-test stabilities, produced by the process of claim 3.

12. An oil having good oxidative, flavor and cold-test stabilities, produced by the process of claim 4.

13. The process of claim 4 in which the bleaching step is carried out at a temperature between 90°C. and 120°C.

14. The process of claim 4 in which the amount of phosphoric acid added in the bleaching step is sufficient to form a mixture with from two one-hundredths of a percent (0.02%) to two tenths of a percent (0.2%) phosphoric acid by weight.

15. The process of claim 4 in which the amount of phosphoric acid added in the bleaching step is sufficient to form a mixture with from three one hundredths of a percent (0.03%) to one tenth of a percent (0.1%) phosphoric acid by weight.