US3173935A - Separation of fatty mixtures - Google Patents

Description

March 16, 1965 w. A. SINGLE'roN SEPARATION oF TATTT mx'ruass Filed Apn l14, 1961 IN1/EN TOR. WILLIAM SNGLETON BY o f n f b ATTORNEY United States Patent O 3,173,935 v SEPARATIN GF FATEY MIXTURES William A. Singleton, Louisville, Ky., assigner to Chernetron Corporation, hicago, Iii., a corporation of Delaware Filed Apr. 14, 196i, Ser. No. 163,691 12 Claims. (Cl. 26d-M9) This invention relates generally to the separation of fatty mixtures into fractions and more particularly to an improved process which may be employed to separate either mixed fatty acids or mixed triglycerides into fractions.

This application is a continuation-in-part of my copending application Serial No. 817,933, tiled lune 3, 1959, now abandoned.

Natural occurring triglycerides, whether of animal or of vegetable origin, in most instances contain both unsaturated and saturated fatty acid radicals. Accordingly, when such triglycerides are subjected to separating processes to produce free fatty acids, mixtures of saturated and unsaturated fatty acids result. With fatty acids of approximately the same number of carbon atoms in the chain the saturated acids have higher melting points than the unsaturated fatty acids. Because of this difference in melting points and other different properties between unsaturated and saturated acids it is frequently desired to separated unsaturated acids from saturated acid in order :to obtain product fractions of greater utility.

In the past the most commonly used method of sep-A arating unsaturated from saturated acids on a commercial scale was the pressing method. This method consists of cooling a molten mix-ture of acids Without agitation until the mixture is partially solidified. The resulting mass is then` enclosed in a porous bag or other filtering medium and subjected to mechanical pressure to force the liquid fraction through the filter medium. This method, is', at best, relatively inefficient in effecting a sharp separation, and in order to obtain fractions of desired commercial purity it is usually necessary to resort to three such cooling and pressing operati-ons in order to achieve a high purity saturated acid fraction. Hence the expression triple pressed has been applied as the conventional term for identifying stearic or other saturated acids of high purity.` The pressing method, however, is generally unsatisfactory for it is quite messy to carry out and involves considerable manual labor. Accordingly, repeated attempts have been made to effect separationof fatty acids on a continuous basis by selective crystallization from a solvent medium. The generally used solvents have been petroleum hydrocarbons such as propane and hexane or non-hydrocarbon solvents such as 4acetone and methanol. A chief difficulty with the prior solvent fractionation processes is that the orsytals formed when the solvent fatty acid mixture is chilled are very ditlicult to filter. Moreover, these crystals include relatively large lamounts of unsaturated material, and in order .to obtain high purity products successive stages of crystallization must be utilized. Moreover, high ratios of solvent to fatty material must be employed necessitating extensive solvent recovery systems and unless slow chilliug with slow crystal growth isemployed, a poor separation is obtained with the result that very large refrigerated chilling devices have been utilized.

All of the foregoing difficulties are also experienced, perhaps to an even greater degree, when attempting to separate unsaturated and saturated triglycerides such as the separation of natural lard into lard oil and a solid saturated triglyceride fraction.

One object of this invention is Ito provide an improved 3,ll3,%5 Patented Mar. i6, i965 lCe continuous process capable of effecting, in a single crystallization step, a relaitvely sharp separation of saturated from unsaturated fatty material.

lt is a further object to effect such separation utilizing a rapid chilling and extremely low solvent to fatty malterial ratios whereby the size of the equipment needed to carry out the process may be maintained at a minimum.

It is a funther object to provide in a fatty material separation process, a readily filterable crystal of the saturated fatty material which is susceptible of highly efficient deposition and washing upon a filter medium.

Other objects and advantages of the process of this invention will pre-sent themselves to those familiar with the art on reading the following detailed specification in conjunction with the drawing and appended claims.

In the drawing, FIG. 1 is a process flow diagram of a continuous plant for carrying out the process of this invention.

I have discovered that, if there is added to a mixture of saturated and unsaturated fatty materials dissolved in a solvent fractional percentage amounts of a class of substances which have the effect of promoting or controlling the crystal growth of the saturated fatty material and that the fthus formed solution is then chilled to a temperature slightly below the precipitation temperature of the saturated material in the solvent, a sharp separation of the saturated fatty material which precipitates in the form of readily filterable crystals may be obtained, Moreover, I have discovered that by utilizing this technique the chilling may be effected very rapidly and a relatively low solvent ratio may be utilized.

The crystals formed by the above described procedure appear upon microscopic examination to have a structure much like grains of sand and Iare generally in the form of irregular granular or spherical particles Whereas if the crystal promoting substance is -not added, the crystals which are normally formed exhibit a slimy plate-like structure and are extremely difiicult, if not impossible, to subject to eflicient filtration and washing operations. lt appears that the saturated fatty acid chains of the crystal promoter which extend outward from ,the kernel become associated with molecules of triglyceride or fatty acid, so that each molecule of crystal promoter is associated with several molecules of triglyceride or fatty acid in the solution. crystallization of the triglyceride or fatty acid occurs during this association, with the result that the crsytals which are formed are approximately equidimensional rather than in the form of fiat plates as they normally occ The equidimensio-nal crystal form is particularly desirable because the crystals are easy to filter Aand the suspension of the crystals in solvent is fluid rather than viscous as in the normal situation where crsyt'al promoters are not used.

A variety of different substances have been found to have the desired crystal promoting effect. substances which l have found to have such effect, however, exhibit the following characteristics: They are compounds having at least four to about 700 satura-ted fatty acid radicals, each radical having between sixteen and twenty-two carbon atoms; the fatty acid radicals may diverge either from a central kernel or from an aliphatic chain. lt is preferred that the saturated fatty acidv radical be identical with the radical of the fatty acid or triglyceride which is the desired product to bev crystallized. The ratio by weight of solvent to fatty material can be within the range of l to l and 4 to l. It is' preferred that the ratio by weight of lsolvent to fatty material be within the range of 1 to l and 2 to l.

From the variety of compounds tested, it appears that the size or configuration of the central kernei or nucleus of the molecule has little or no effect upon the effectiveness All of the' of crystal promoters of this type. Rather, it is important only that the kernel or nucleus be capable of attaching branches such as the saturated fatty acid radical chain in such a manner that they extend from the kernel or nucleus in more than one plane.

One of the preferred types of crystal promoter used in this invention comprises polyvinyl esters of fatty acids wherein the fatty acids contain 16 to 22 carbon atoms. For instance, polyvinyl stearate having on the average about 50 ester groups per molecule is an extremely effective crystal promoter. However, polyvinyl stearate of higher molecular weight is also effective. For instance,

polyvinyl stearate of an average molecular weight of 90,-

000 (about 300 ester units per molecule) has been shown to be extremely effective. Another specimen of polyvinyl stearate having an average molecular weight of about 200,000 is effective. This substance has approximately 700 ester linkages per molecule.

Polyvinyl esters of fatty acids, such as oleic and related unsaturated acids also form effective crystal promoters. For instance, a polyvinyl ester of lard fatty acids having approximately 50 ester groups per molecule is as effective as polyvinyl stearate of approximately the same molecular weight. Polyvinyl esters made from soybean oil fatty acids (containing not more than about 15% saturated higher fatty acids) have approximately the same effectiveness as crystal promoters as polyvinyl stearate of the same molecular weight. On the other hand, a polyvinyl ester made from tall oil fatty acids which consist almost entirely of unsaturated acids was ineffective, which seems to indicate that it is necessary to have some saturated fatty acid radicals containing 16 to 22 carbons atoms present, but that the proportion need not be more than or Mixed polyvinyl esters of acetic and fatty acids, such as polyvinyl acetate palmitate and polyvinyl acetate stearate, are effective crystallization promoters even though the higher fatty acid radicals amount to only five or six per molecule.

The esters which are effective as crystal promoters have melting points which vary over a fairly wide range without adversely influencing the effectiveness of the materials. For instance, polyvinyl stearate with a melting point of about 44 C. has good effectiveness while polyvinyl stearates containing mixed acids of lard or coconut oil are also effective even though they do not crystallize at temperatures as low as 60 C. The molecular weight of the polyvinyl ester does not seem to have any great influence on the effectiveness of the crystal promoters as shown by the fact that polyvinyl fatty acid esters with molecular weights from about 1500 to about 700,000 are effective without any significant change in effectivness.

Fatty acid esters of polyhydric substances, such as sugars and sugar derivatives, are generally effective as crystal promoters so long as they contain 4 or more fatty acid ester groups wherein the fatty acid contains 16 to 22 carbon atoms. For instance, sucrose with most of its hydroxyl groups esterified with stearic acid is quite effective whereas sucrose dipalmitate is ineffecive at 0.2% concentration. This indicates that the number of fatty acid groups per molecule is important. Methyl glucoside, which contains 5 hydroxyl radicals, produces a moderately effective crystal promoter when fully esterified with stearic acid.

Aluminum salts of fatty acids, such as aluminum stearate, are effective when suspended in oils or fats before being added to the solution to be crystallized, whereas ordinary aluminum stearate without presolution in oils or fats is ineffective. For instance, 9 parts of melted stearic acid are admixed with 1 part of aluminum stearate and the mixture allowed to cool and solidify. This product after being disintegrated into chips is highly effective in inducing crystallization of saturated fatty acids from solutions containing the same. Likewise, the aluminum salt of tallow acids when dissolved in an excess of solidied tallow acids and disintegrated is also effective for crystallization of fatty acids.

Polyamide resins derived from fatty acids and alkylenediamines are effective in promoting crystallization of fatty acids. These resins are condensation polymers of dimerized and trimerized unsaturated fatty acids from vegetable oils, and of aromatic or aliphatic polyamines. For instance, the methyl esters of soybean fatty acids (linoleic and linolenic acids) are suitably polymerized and then condensed with an equivalent amount of ethylenediamine at 15G-225 C. in an inert atmosphere, the reaction being completed under vacuum at 20G-225 C. Similar polyamide resins are produced from linoleic, linolenic and eleostearic acids found in linseed, tung and dehydrated castor oils. Polyamines which are suitable include ethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, propylenediamine and butylenediamine. Such polyamide resins have molecular weights of 300D-5000 and are soluble in common organic solvents, such as isopropyl alcohol, n-butyl alcohol, chloroform, cyclohexanol and pyridine. The preparation and properties of such polyamide resins are described by Cowan et al., Oil and Soap, pp. 760 et seq. (1941); Cowan et al., Oil and Soap, pp. 101-107 (1941); Falkenberg et al., Oil and Soap, pp. 143-147 (1945) and Renfrew et al., Industrial and Engineering Chemistry, Vol. 46, pp. 2226- 2231 (1954).

Substances which have been tested and which clearly do not produce the desired result are as follows: natural waxes, shellac, rosin, various triglycerides, polyethylene, dimerized fatty acids, various amines such as octylamine, ethylene diamine, tetraethylene pentamine, butyl stearate, methoxyethyl stearate, sorbitan tristearate, polyvinyl esters of the following: unhydrogenated soybean oil acids, tall oil fatty acids and lauric acid.

The minimum amount of modifier required depends upon the particular modifier and in most cases appears to be approximately one tenth of one percent by weight of the fatty material. In most instances two tenths of one percent by weight is the preferred amount, particularly when the preferred modifier as described in Example l below is utilized. Some of the materials listed above as being satisfactory are substantially more effective than others, however, and it has been found that as little as 0.02% of a polyvinyl ester made from commercial grade saturated stearic acid is adequate to produce the desired crystal structure. This is the most active promoting material which has been investigated. The maximum amount of promoter which is practical to use is approximately one percent. Over this amount product contamination results and the process is rendered unnecessarily costly. It is, of course, preferred in any operation to utilize as little modier as is required.

The process of this invention will be more clearly understood by reference to the drawing which is a process flow diagram of the system of equipment. The fatty material to be separated is fed to the system from storage 1t) through heater 11. It next passes through a vacuum dryer 12 where moisture is removed through steam ejector 13. The crystal promoter from a source of supply indicated at 13a is mixed with the effluent from the drier and the mixture is cooled in exchanger 14 to a point just above the crystallization temperature of the material. The fatty material is then admixed with solvent Wash entering through line 16 from wash solvent receiver 17. Solvent line 15 is utilized only upon start up of the plant. At this stage the stream consists of mixed fatty material and crystal promoter all dissovled in solvent. This stream passes through line 18 into a scraped surface heat exchanger 20 of the type sold under the trade name Votator. n this heat exchanger the solution is rapidly chilled through a range of approximately F. to a temperature at which the saturated fatty material precipitates in the desired sand-like crystal acids, having an iodine value of 50, and 56 parts of acetone, together with 4 parts of anhydrous methanol was prepared and heated to a temperature of 100 F. to effect complete solution of the tallow fatty acids in the mixed solvent. The ratio of solvent to fatty material was 11/2 to 1. The solution was pumped through a Votator scraped surface heat exchanger at a rate of 75 pounds per hour and Iwas cooled by indirect heat exchange with liquid ammonia to a temperature of 4 F. The rate of cooling was such that the total residence time in the Votator heat exchanger Was approximately 45 seconds. The slurry emerging from the Votator heat exchanger was extremely viscous and slimy in nature. Attempts to separate the solid and liquid phases of the slurry by filtration were not successful.

Example 3 A mixture identical with that described in Example 2 was prepared and heated to 100 F. to effect complete solution. To 100 parts of the solution there was added three tenths part of a mixture consisting of 30% of the crystal modifier, prepared according to Example l, and 70% tallow acids. The added constituents dissolved immediately in the hot solution. The resulting solution was pumped through a Votator heat exchanger at a rate of 75 pounds per hour and was chilled to a temperature of F. during the 45 seconds residence time. The emerging slurry was found to be relatively non-viscous and was readily filterable. The slurry was filtered, and the filter cake was washed with solvent consisting of acetone containing 10% methanol. The filter cake was freed of solvent by evaporation and the resulting saturated fatty acid fraction was found to have an iodine value of 5.2. The filtrate was freed of solvent likewise by evaporation and contained an unsaturated fraction having an iodine value of 99.5.

Example 4 There were continuously supplied to a system of apparatus similar to that shown in the drawing distilled tallow fatty acids having an iodine Value of 72.1. These acids were pumped at a rate of 74 pounds per hour and were admixed continuously with crystal promoter, made in accordance with Example 1, which entered the system of apparatus at a rate of 0.11 pound per hour. The fatty acids and crystal modifier were heated to a temperature of approximately 120 F. and were then contacted with acetone supplied at a rate of 148 pounds per hour. Thus the ratio of solvent to fatty material was 2 to 1, and it was found that the fatty acids and crystal promoter were completely dissolved in the acetone which had a temperature of 55 F. The resulting solution of fatty acids in solvent was found to have a temperature of 77 F. and at this temperature Was introduced into the Votator heat exchanger where it was rapidly cooled to a temperature of about 15 F.

The slurry emerging from the Votator chiller was filtered and washed with acetone upon a rotary drum filter and thereby separated into two fractions. The saturated fraction was found to have an iodine Value of 5.8 and constituted 50.4% of the original tallow acids. The unsaturated fraction was found to have an iodine value of 95.8 and constituted 49.6% of the original acids. The slurry of this example was very uid and readily filterable.

Example 5 There was continuously supplied to a system of apparatus similar to that shown in the drawing a natural lard having an idoine value of 70. This lard was pumped at a rate of 72.5 pounds per hour and was admixed with 0.2% of crystal promoter, made in accordance with Example 1, introducedat a rate of 0.14 pound per hour. The mixture of lard and modifier was heated to a temperature of 100 F. and was admixed with acetone at a temperature of 75 F. and supplied at a rate of 128 pounds per hour. The ratio of the solvent 'to lard feed was 1.75 to 1, and the resulting solvent-lard solution had a temperature of 84 F. This solution was pumped through the chiller and emerged at a temperature of 28 F. From the chiller the resulting slurry Was conducted to a filter, but the filter cake was not washed as in the previous examples. The filter cake was removed from the filter at a rate of 52.5 (on a solvent-free basis) pounds per hour and constituted 72.4% of the feed. The iodine value of the filter cake was 62. The filtrate was collected at a rate of 20 pounds per hour (on a solventfree basis) and constituted 27.6% of the feed. The iodine value of lthis relatively unsaturated fraction was found to be 82. Solvent was removed from both the filter cake and the filtrate in the same manner as in the preceding example. To determine the suitability of the unsaturated filtrate fraction for use as a salad oil it was subjected to a cold test at 32 F. and failed to demonstrate clouding or precipitation for 2% hours.

Example 6 One kilo of -stearic acid yfrom hydrogenated soybean oil was dissolved in 2 liters of a mixture of acetone and anhydrous methanol (9 volumes to 1 volume). Two grams of polyvinyl steanat-e was dissolved in the solution. The polyvinyl stearate had been produced by ester interchange between polyvinyl acetate and methoxyethyl stearate and contained about 700 ester units per molecule. The polyvinyl stearate contained approximately 60 moles of stearic acid to 40 molles of acetic acid after the ester interchange. The fatty acid used in producing the ester was approximately 88% stearic acid, 10% palmitic acid, 1% arachidic acid and 1% oleic acid.

The resulting solution was heated to 60 C. to insure complete solution, then cooled to 50 C. in the air, fol- -lowed by cooling with stirring in a water bath kept at 15 C. After the mixture reached 25 C. it Was chilled in an ice bath until the temperature reached 5 C. At 19.2 C. the solution became cloudy and crystallization occurred. The grainy precipitate of stearic acid was collected on a filter, pressed and allowed to dry in the air. The mixture was more fluid and grainy than when the polyvinyl stearate had not been added. Without the additive the mixture was a Ithick slurry with a Achar-acteristic pearly sheen.

Example 7 One kilo of commercial saturated fatty acid dissolved in 2 liters of a mixture of acetone (9 volumes) and anhydrous methanol (l volume) was treated with 0.2 lgram (0.02%) of .polyvinyl palttnitate stearate made by acidolysis of polyvinyl acetate by commercial fatty acid containing 52% palmitic acid, 47% stearic acid and 1% oleic acid. Approximately 68% of the acetate radicals of the polyvinyl acetate were replaced by fatty acid radical-s during the acidolysis to produce the polyvinyl palmitate stearate. The solution was heated to 60 C. to obtain complete solution, then cooled to 50 C. in the air. The mixture was stirred and cooled in a Water bath maintained at 15 C. until the .temperature of the solution reached 25 C. The mixture was then chilled with ice Water until the `temperature of the mixture reached 5 C. A clouding temperature of 17.6 C. was observed and a granular precipitate of saturated fatty acids was obtained which was easy to remove from the iiuid mixture by filtration and pressing. Without the additive the mixture was very viscous and formed a soapy slurry having a characteristic pearly sheen.

The polyvinyl acetate used .in this experiment was of low viscosity having an average of between 50 and 60 repeating vinyl units per molecule and the product of mixed polyvinyl fatty acid 4esters had an average molecular weight of approximately 15,000.

Example 8 A mixture of 9 parts by Weight of commercial triple 9 pressed stearic acid and l part by weight of polyvinyl stearato (approximate molecular weight 200,000) was melted, thoroughly rnixed .and chilled. The solid product was converted into iiakes for use as la crystal promoting additive.

One kilo of mixed acids obtained from a mixture of hydrogenated and unhydrogenated soybean oils was dissolved in 2 liters of a mixture of acetone (9 volumes) and .anhydrous methanol (1 volume). To the solution was .added 20 grams of flakes of polyvinyl stearato dissolved in stearic acid. The solution was then heated to 60 C., allowed to cool at 50 C. at room temperature, then chil-led with agitation in a water bath at 15 C. The mixture became cloudy at 17.7 C. It was then placed in an ice bat-h and cooled to 5 C. 'I'he crystalline granular precipitate of stearic acid was removed by filtration, pressed and dried. A similar run without the additive of polyvinyl steara-te .gave a highly viscous slurry from which the stearic acid was very difficult to remove by filtration.

Example 9 (A) A mixture of 1 p-alrt of polyvinyl stearate in 9 parts of saturated cottonsecd oil was melted, agitated until homogeneous and chilled. This product was convert-ed into flakes which were effective as crystallization promoters for saturated fatty acids.

(B) One part of aluminum steara-te admixed with 19 parts of commercial triple pressed stearic acid ywas melted, agitated until homogeneous, chilled and converted into flakes. These flakes were effective as crystallization promoters in solid fatty racids.

Example 10 To a solution of one kilo of tallow fatty acids dissolved in two liters of a mixture of acetone and anhydrous methanol (9 volumes: 1 voume) was added 2 grams of a polyamide resin produced from dimerized `and trimerized methyl esters of linseed oil fatty acids with an @equivalent amount of ethylenediamine. This polyamide resin was produced by the method of Cowan et all., Oil and Soap, April 1944, pp. 101-107. The resulting solution was heated to 60 C. to insure complete solution, then cooled to 50 C. in the air followed by cooling with stirring in a water bath kept at C. After the solution reached C., yit was chilled in an ice bath until the temperature reached about 5 C. At 19.2 C., the solution became cloudy and crystallization began. A grainy precipitate of stea-ric acid was leasily filtered on a filter press and dried in the air.

The same procedure with the same quantities of materials but without the polyamide resin led to a slimy precipitate of stealric `acid in a viscous suspension which wasl very difficult to filter and afforded low purity stearic aci From the foregoing detailed description it will be readily apparent that a lgreatly improved fatty material separation process has been provided. Various changes and modifications in the process of this invention, such as will present themselves to those who are familiar with the art, may be made without departing from the spirit of this invent-ion.

What is claimed as new and is desired to be obtained by Letters Patent of the United States is:

l. The process of separating fatty material selected from the group consisting of (l) mixtures of saturated and unsaturated fatty acids and (2) mixtures of relatively saturated and unsaturated triglycerides into saturated and unsaturated fractions by crystallization, said process comprising forming a solution of said fatty material in a solvent for same, said solution also containing between about 0.01% and 1% of a crystal promoter, said crystal promoter being a compound selected from the group consisting of polyvinyl fatty acid esters, fatty acid esters of polyhydric alcohols containing at least four hydroxyl radicals, polyamide resins and aluminum salts of fatty acids in fibrous mycelle structure, said aluminum salts being Suspended in an oil selected from the group consisting of fatty acids and fatty acid triglycerides, said promotor containing between 4 and 700 saturated fatty acid radical chains extending in more than one plane, each of said chains having between 16 and 22 carbon atoms, said cry"- tal promoter in the amount utilized being soluble in the solvent-fatty material solution, chilling the composite solution of fatty material and crystal promoter to a temperature sufficiently low that the more saturated fatty components of said fatty material mixture are precipitated in the form of discrete non-slimy, readily iilterable, sandlike crystals, separating the thus-formed crystals from the mother liquor, and removing solvent from said mother liquor to obtain an unsaturated fatty material fraction separate from the thus-crystallized more saturated fatty material fraction.

2. The process of claim l in which the fatty material consists of a mixture of fatty acids.

3. The process of claim 1 in which the fatty material is a naturally occurring triglyceride.

4. The process of claim 1 in which the ratio by Weight of solvent to fatty material is Within the range of 1 to l and 2 to 1.

5. The process of claim 1 in which the step of chilling the composite solution to effect precipitation of the more saturated fatty material is effected in less than one minute.

6. The process of claim S in which the ratio by weight of solvent to fatty material is Within the range of 1 to 1 and 2 to l.

7. The process of claim 1 in which the crystal promoter is a polyvinyl ester of a saturated fatty acid containing 16 to 22 carbon atoms.

8. The process of claim 1 in which the crystal promoter is methyl glucoside stearate.

9. The process of claim 1 in which the crystal promoter is a palmitic ester of a polyalcohol containing at least four hydroxyl radicals.

10. The process of claim 1 in which the crystal promoter is aluminum stearate in an oil suspension.

1l. The process of claim 1 in which the crystal promoter is a sucrose ester of a saturated fatty acid containing 16 to 22 carbon atoms,

12. The process of claim l in which the crystal promoter is a polymerized triglyceride composition obtained by heating said triglyceride to a temperature in the range of about 260 to 280 C. in the presence of air.

References Cited in the tile of this patent UNITED STATES PATENTS 2,266,544 Freuler Nov. 1S, 1938 2,608,563 Griffin Aug. 26, 1952 2,759,923 Gibbons a- Aug. 2l, 1956 2,884,430 Baumgartner Apr. 28, 1959 2,889,338 Dazzi June 2, 1959 2,997,492 Martin Aug. 22, 196-1

Claims (1)

1. THE PROCESS OF SEPARATING FATTY MATERIAL SELECTED FROM THE GROUP CONSISTING OF (1) MIXTURES OF SATURATED AND UNSATURATED FATTY ACIDS AND (2) MIXTURES OF RELATIVELY SATURATED AND UNSATURATED TRIGLYCERIDES INTO SATURATED AND UNSATURATED FRACTIONS BY CRYSTALLIZATION, SAID PROCESS COMPRISING FORMING A SOLUTION OF SAID FATTY MATERIAL IN A SOLVENT FOR SAME, SAID SOLUTION ALSO CONTAINING BETWEEN ABOUT 0.01% ANG 1% OF A CRYSTAL PROMOTER, SAID CRYSTAL PROMOTER BEING A COMPOUND SELECTED FROM THE GROUP CONSISTING OF POLYVINYL FATTY ACID ESTERS, FATTY ACID ESTERS OF POLYHYDRIC ALCOHOLS CONTAINING AT LEAST FOUR HYDROXYL RADICALS, POLYAMIDE RESINS AND ALUMINUM SALTS OF FATTY ACIDS IN FIBROUS MYCELLE STRUCTURE, SAID ALUMINUM SALTS BEING SUSPENDED IN AN OIL SELECTED FROM THE GROUP CONSISTING OF FATTY ACIDS AND FATTY ACID TRIGLYCERIDES, SAID PROMOTOR CONTAINING BETWEEN 4 AND 700 SATURATED FATTY ACID RADICAL CHAINS EXTENDING IN MORE THAN ONE PLANE, EACH OF SAID CHAINS HAVING BETWEEN 16 AND 22 CARBON ATOMS, SAID CRYSTAL PROMOTER IN THE AMOUNT UTILIZED BEING SOLUBLE IN THE SOLVENT-FATTY MATERIAL SOLUTION, CHILLING THE COMPOSITE SOLUTION OF FATTY MATERIAL AND CRYSTAL PROMOTER TO A TEMPERATURE SUFFICIENTLY LOW THAT THE MORE SATURATED FATTY COMPONENTS OF SAID FATTY MATERIAL MIXTURE ARE PRECIPITATED IN THE FORM OF DISCRETE NON-SLIMY, READILY FILTERABLE, SANDLIKE CRYSTALS, SEPARATING THE THUS-FORMED CRYSTALS FROM THE MOTHER LIQUOR, AND REMOVING SOLVENT FROM SAID MOTHER LIQUOR TO OBTAIN AN UNSATURATED FATTY MATERIAL FRACTION SEPARATE FROM THE THUS-CRYSTALLIZED MORE SATURATED FATTY MATERIAL FRACTION.

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