US2673868A

US2673868A - Color stabilization of fatty materials

Info

Publication number: US2673868A
Application number: US232869A
Authority: US
Inventors: Robert J Hlavacek
Original assignee: Swift and Co Inc
Current assignee: JBS USA LLC
Priority date: 1951-06-21
Filing date: 1951-06-21
Publication date: 1954-03-30
Anticipated expiration: 1971-03-30

Description

Patented Mar. 30, 1954 UNITED STATES TENT OFFICE COLOR STABILIZATION F FATTY MATERIALS Illinois No Drawing. Application June 21, 1951, Serial No. 232,869

7 Claims. (Cl. 260-398.5)

The present invention relates in general to a method of preventing color reversion in fatty materials, and more particularly to a method for stabilizing fatty materials, decolcrized by treatment with a liquefied normally gaseous hydrocarbon, so as to prevent subsequent color reversion of the decolorized fatty material.

The use of propane or other liquefied, normally aseous hydrocarbons, such as ethane, butane or mixtures thereof, to remove colored impurities from fats and fatty acids is known to the prior art and has been described in U. S. Patents 2,118,454; 2,219,652; 2,383,535; and 2,367,671. Essentially, the process comprises dissolving the fatty material under pressure in several volumes of a liquefied, normally gaseous hydrocarbon maintained at elevated temperatures and pressures whereby two phases are formed--the lighter phase containing the decolorized fatty material and the heavier or lower phase containing color bodies and tarry impurities. The upper phase is removed and the hydrocarbon separated from the fatty material by means of distillation to produce a decolorized product. Preferably, the process is carried out as a continuous countercurrent process for most efficient results.

It has been found that when a fat such as an inedible tallow or the like is decolorized by treatment with a liquefied, normally gaseous hydrocarbon, it has a pronounced tendency to darken or color-revert appreciably when kept hot and exposed to air. Normal fat antioxidants added to the fatty material after decolorization do not materially improve the color reversion situation. A major reason for the ineffectiveness of antioxidants in general as color stabilizers is due to the fact that oxidation is but a small part of color reversion. Antioxidants, in general, are of little value as color stabilizers, and the stabilization against color reversion of low-grade fats which have been, or are to be, propane-decolorized presents a much more dimcult problem than the stabilization of a high-grade fat to oxidation.

It is, therefore, an object of the present invention to provide a method for stabilizing fatty material against color reversion.

It is another object of the invention to provide a method for pretreating inedible fatty stock to be decolorized by treatment with a liquefied, normally gaseous hydrocarbon to prevent subsequent color reversion of the decolorized fatty material.

It is a further object of the invention to provide a method for stabilizing inedible fatty materials, which have been propane-decolorized, against color reversion.

Additional objects, if not specifically set forth herein, will be readily apparent to one skilled 2 in the art from the following detailed description of the invention.

The present invention in general is based on the discovery that hypophosphorous acid will effectively stabilize the color reversion of fatty materials which have been decolorized by treatment with a liquefied, normally gaseous hydrocarbon. I'he hypophosphorous acid may be added to the fatty material after decolorization or preferably to the fatty stock prior to decolorization. This latter preferred method produces a decolorized product which is far more stable than a'product which has been decolorized without pretreatment.

When used for pretreating the fatty stock, the hypophosphorous acid should be added in an amount around 1 per cent by weight or more of the fatty stock, and the treated stock held for preferably about 4. hours at an elevated temperature before decolorizing. This holding period has been found to provide substantial improvement to the color-stability of oils containing the hypophosphorous acid. The time of holding may vary depending on the temperature of holding and on the amount of hypophosphorous acid employed. A holding period of at least 1 hour at around. 200 F. is required, and preferably as indicated above, a 4-hour holding period is employed. The holding temperature may vary from about 180 F. to about 268 F. The hypophosphorous acid may be added to the stock in the form of a 50 per cent aqueous solution desired. Preferably, the treated stock is then held overnight at about 149 F. to settle, the foots drawn off, and the acid-washed oil decolorized.

When used as an additive to fatty materials after decolorization by treatment with a liquefied, normally gaseous hydrocarbon, the concentration of hypophosphorous acid should be about 0.5 per cent by weight of the fatty material. In practice, the hypophosphorou acid may be added manually to the decolorized fatty materials and thoroughly mixed therewith, or preferably added through a proportioning pump or the like into the decolorized product as it leaves the decolorizing operation. The fatty material to which the hypophosphorous acid is added must be about 1030 F. above the temperature at which it is completely liquid (about -175 F. depending on the particular fatty material being treated). Decolorized oils, after processing, are kept at these temperatures, 1. e. 10-30 F. above the point at which they are fluid, only long enough to accumulate an amount sufiiciently large to pump to an empty tank car or storage tank, after which the oils are allowed to cool and solidify. This means that in plant operations, such fatty materials will ordinarily be held at l40-175 F. from 24 to 48 hours. Laboratory testing was carried out at aggravated temperature conditions in order to accelerate any reversion tendencies of the fatty materials treated in accordance with the present invention. The concentration of hypophosphorous acid may vary from about 0.3 per cent up to about 1.0 per cent depending on the fatty material treated. Storage at 140 F., as illustrated in Example If and simulating plant holding conditions, resulted in an initial reversion of one FAC color unit, followed by a return to the original color. Storage at higher temperatures (200 F.) in closed containers to provide accelerated reversion conditions resulted in a direct bleach of from 1 to 3 FAG color units. Samples were stored in e-ounce oil sample bottles, stoppered and unstoppered. Stabilized sample containing less than 90 per cent f. f. a. were stored with a small piece of black iron wire to simulate plant conditions wherein decolorized fats are stored in iron tanks.

The percentage of hypophosphorous acid required is relatively large, ranging from about 6.3 per cent to about 1.0 per cent by weight of the fatty material when used as an additive after decolorization. When used in pretreating the fatty materials to be decolorized at least about 1.0 per cent by weight is desirable although larger or smaller amounts are beneficial, the larger amount usually being limited by economic considerations.

It has been found that hypopiiosphorous acid alone and not the salts thereof will function to inhibit color reversion. It functions equally well under an air or inert gas atmosphere, thus indicating that it is not a deoxygenating process.

The following examples, utilizing propane as the liquefied, normally gaseous hydrocarbon, are furnished for the purpose of illustration only:

Example I Acidulated soybean foots were pretreated with hypophosphorous acid by agitating the foots with 1.0 per cent hypophosphorous acid for 4 hours at HEW-200 F. The stock was allowed to settle overnight at about 140 F. and the foots drawn off. This material was then subjected to counter-current propane decolorizing at 200 R, 679 p. s. i. g. and a 25:1 propane to fat ratio. The overhead product recovered had an FAG color of 9-11A.

Erample If Samples of decolorized fatty materials from. the propane decolorizing operation were treated with varying percentages of hypophosohorous acid and held at 145? F. until signs of color reversion appeared. The following table shows the results of this treatment:

Percent 31 llecolorized Fatty Material tarot flfitfi Added. (days) 0. 1 54 1. 0 2 54 0. 3 3 Yellow grease 0. 5 29 butane or mixtures thereof. The term "fatty maerials as used in the appended claims is intended to cover animal fats, particularly inedible greases and tallows; fatty acids, such as tallow fatty acids, stearic acid, and soybean foots fatty acids; and vegetable fats and oils, for example, soybean and cottonseed oils, soybean and cottonseed foots, and the like.

Although the invention has been described in connection with the treatment of fatty materials decolorized or to be decolorized with normally gaseous hydrocarbons, it is also applicable to treatment of fatty materials subject to decolorization with other decolorizing solvents as, for example, acetone, methyl ethyl ketone and lower aliphatic liquid hydrocarbons, such as butane or isobutane, etc.

Obviously, many modifications and variations of the invention hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A method for inhibiting color reversion in fatty materials which have been decolorized by treatment with a liquefied normally, gaseous hydrocarbon which comprises incorporating in said fatty materials while in the liquid state a small amount of hypophosphorous acid.

2. A method as in claim 1 wherein the hypophosphorous acid is present in from about 0.3 per cut to about 1.0 per cent by weight of the fatty material.

3. A method for inhibiting color reversion in fatty materials which are to be decolorized by treatment with a liquefied, normally gaseous hydrocarbon comprising incorporating with said fatty materials prior to decolorization a small amount of hypophosphorous acid, maintaining said fatty materials so treated at an elevated temperature for at least 1 hour, and thereafter subjecting said fatty materials containing said hypophosphorous acid to a decolorization treatment with a liquefied, normally gaseous hydrocarbon.

4. A method as in claim 3, wherein the hypophosphorous acid is present in about 1.0 per cent by weight of the fatty material.

5. A method for inhibiting color reversion in fatty materials, which comprises incorporating with said fatty materials a small amount of hypophosphorous acid, maintaining said fatty material containing said acid at about l200 F. for at least 1 hour, and thereafter subjecting said fatty material containing said acid to a countercurrent decolorizing operation with a liquefied, normally gaseous hydrocarbon.

6. The improvement in the liquefied, normally gaseous hydrocarbon decolorization and stabilization to color reversion of fatty materials, which comprises treating sai fatty materials with a small amount of hypophosp-horous acid.

7. A method for inhibiting color reversion in fatty materials which have been decolorized by treatment with liquefied normally gaseous propane which comprises incorporating in said fatty materials while in the liquid state a small amount of hypophosphorous acid.

ROBERT J. I-ILAVACEK.

Name Date Heuser Aug. 18, 1925 Number