US2572467A - Concentration and recovery of carotenoid pigments from palm oil - Google Patents

Description

patented ()ct. 23, i951 UNITED STATES PATENT OFFICE 1 I v 2,572,467 v Q CONCENTRATION AND RECOVERY OF CA- ao'rENom PIGMENTS FROM PALM 01L Arthur Ira Gebhartg; Union, N. J., assig'nor to Qolgate-Palmoliv'e-Peet Company, Jersey City,- N. J a corporation of Delaware No Drawing. Application August 4, 1949; Serial N0. 108,649

12 Claims. 1

This invention relates to an improved process for the concentration and recovery of the caroteno-id pigments, and more specifically the'carov tenes or provitamins A from palm oil.

Any means of recovery of the carotenoid content and the like must take into consideration the complex character of the parent palm oil material and of the carotenoid substances contained therein. Palm oil is a mixture of triglycerides of a variety of higher fatty acids and possesses generally significant amounts of free acids in addition to unsaponifiable matter such as the carotenoids, sterols, nitrogenous matter, etc. The carotenoid pigments are present in relatively minute quantities of the order of about 0.05-0.20%; they are heat and air unstable, of high molecular weight, oil soluble and hydrocarbon in character generally. The aggregate of these various factors render the concentration and recovery of the carotenoids diflicult in prior art processes.

Heretofore, a common technique for the recovery of carotenoid pigments has involved usually the saponification of the fatty oil and extraction of the unsaponifiable fraction with a suitable selective solvent. This procedure is limited by the necessity for handling comparatively large volumes of immiscible and frequently emulsifiable liquids and the provitamin A fraction is recovered admixed with other unsaponifiable matter. In another process, crude palm oil may be dissolved in a solvent and a certain portion of the glycerides and the free fatty acids may be separated therefrom by crystallization. Thereafter, the residual fatty acids may be neutralized and a soap phase separated therefrom. The recovery of the "carotenoid pigments is incomplete therein due to an affinity or solubility of the triglycerides for the carotene substances, and to the possible formation of emulsion in the presence of the soap which would interfere with the sharp separation of an aqueous phase.

Another procedure different in character involves the alcoholysis of palm oil and the separation of the provitamins by distillation. This procedure results in fair yields but involves the use of high temperatures and complex and costly operating techniques including high vacuum distillation A simple and economical process has now been developed for-the concentration and recovery of the carotenoid fraction from palm oil. Broadly, the present invention comprises the concentration of the carotenoid pigments from carotenoid-.- c'ontaining fatty mixture derived from the by- 260-2265) 2 drolysis and alcoholysis of palm oil by treatment with an inert selective solvent and crystallization of at least the major portion of the fatty products present in such mixtures therefrom. By means of the application of various splitting processes, the original palm oil may be rendered substantially free of triglycerides and converted simultaneously to compositions comprising essentially free fatty acids or their alkyl esters, which are amenable to solvent crystallization at low temperatures of the fatty constituents such that the desired carotenoid compounds may be recovered in a highly concentrated form and unimpaired condition from the remaining solution.

Accordingly, the present invention contemplates the hydrolysis of the palm oil in any suitable manner such that decomposition of the carotenoid pigments does not occur appreciably. Since the carotenoid substances are heat labile, the conventional types of splitting processes utilizing high temperatures of the order of 250. C. are undesirable herein. A preferred manner of preparing a hydrolyzed palm oil involves the two stage process of saponification of the palm oil at relatively low temperatures and acidification of the resulting soaps to the freeacids.

The palm oil may be saponified in any suitable manner, either by batch, semi-continuous or continuous operations. The saponification is accomplished by the reaction of the palm oil with an alkaline saponifying agent or mixtures of such agents, preferably those having an alkali metal or alkaline earth metal as the cation. Since relatively low temperatures are to be employed, it is preferred to use the caustic alkalies such as sodium and potassium hydroxide. The proportion of alkaline saponifying agent should be sufiicient to insure substantially complete saponification of the fatty acidspresent in both the free state and in combined form as esters in the palm oil. Accordingly, approximately a molar equiv-' alent and preferably an excess (generally up to about a 25% excess) of saponifying agent may be utilized in order to effect saponification. The saponifying agent may be added either as an aqueous solution or. dissolved ina suitable'diluent, particularly an organic solvent such as ethyl alcohol.

During saponification, any appreciable decomposition of the carotenoid fraction should be avoided to insure maximum recovery of the same. The suitable temperature range should be less than about 150 C., and preferably not more than 100 C. with best results attainable by the use of temperatures not greater than about C. If

desired, reduced pressure may be employed advantageously as a means of limiting temperature and oxidation effects. Saponification with an alcoholic caustic solution is a particularly satisfactory procedure since the reaction may be conducted 'WlthQllt carotenoid decomposition at about the boiling point of the alcohol.

The time of heat treatment is always a factor to be considered and correlated with the particular temperature selected for the reaction. If appreciable decomposition of the carotenoids 'oc curs at the higher temperatures,'the temperature and/or time of treatment should'be reduced aceordingly;

At ordinary temperatures, the carotenoid pigments in palm oil are reasonably stable to air but characteristically are liable to decomposition by oxidation, particularly at elevated temperatures. The presence of air therefore at the temperatures to be employed during the saponification reaction is not .p'erf-erred, though it need not be excluded'necessarily. The use of a closed system, a -vacuum'or'of 'an-inert atmosphere (e. g. nitrogen) may be employed advantageously.

The saponified mass substantially completely free of triglycerides may then be subjected to acidification in any suitable manner to convert the soaps to the free fatty acids. A common procedure involves the addition of a suitable acidic material, -e. g.-a dilute solution of sulphuric, phosphoric "or hydrochloric acids, in an amount sufficient to attain at least about a pH of '7 and preferably about 4 or 5 in the reaction mixture.

Upon acidification and settling, two layers are formed which may be'zseparated preferably. The lower aqueous layer contains the soluble salts, glycerine and excess acid and the upper fatty acid layer'contains the carotenoids. If desired, this upper layer maybe water washed and dried to achieve additional purification before subjecting the mass to the requisite solvent crystallization treatment.

Similarly, the palm oil may be subjected to alcoholysis to form the desired readily crystallizable mixture. et al. U. S. Patent No. 2,383,579; Dreger, U. S. Patent No. 2,383,596; and Trent, U. S. Patents Nos. 2,383,632 .and 2,432,181 are applicable herein.

In such alcoholysis processes, the palm oil is treated at low temperatures with a suitable monohydric alcohol, generally in the presence of an alcoholysis catalyst whereby conversion of the triglycerides to the fatty acid esters of the monohydric alcohols occurs rapidly. The monohydric alcohols arepreferably. the saturated aliphatic 01165701. not more than about 6 carbon atoms, such as-methyL'ethyl, propyl, butyl alcohols, etc.

The rate of the alcoholysis reaction is largely determined by the temperature and the presence or absence of suitable catalysts. If a catalyst is used, an advantageous temperature range is from about 20 to 150 'C. The alcoholysis reaction proceeds'q'uite rapidly even at room temperature in the presence of a catalyst but proceeds even more rapidly at elevated temperatures. Suitable preferred catalysts are the alkaline materials suchas sodium hydroxide, sodium alcoholate, etc. Since the carotenoid compounds are heat unstable, the use of high temperatures tends to promote decomposition of the :same. In order to .prevent substantial decomposition of the carotenoid pigments, the temperature and the time of treatment should be kept to a minimum consistent with substantially complete conversion of the triglycerides to the alkyl esters. Thus the The processes disclosed by Allen treated in any suitable manner to remove unreacted alcohol, glycerine, etc. As a preferred technique, the reaction mixture may be allowed to settle into layers wherein the upper layer contains the alkyl esters, excess alcohol, and unsa'pbnifiables including the carotenoids. and the glycerine is concentrated with some alcohol in the lower layer. The two phases may be separated in any convenient manner such as by decantation. The upper layer may be washed with water or aqueous alcohol to separate residual glycerine and the excess alcohol. Alternative to settling, the entire reaction mass may be washed as-a means of removing the glycerine and excess alcohol or the alcohol could be removed by distillation. The alkyl ester fraction containing the carotenoids may now be subjected to the crystallization procedure. It is preferable however to neutralize the alkaline catalyst, if one has been employed for the alcoholysis reaction, either before the washing or the crystallization treatments 'to remove any .possible soap which has formed in the reaction mixture.

Alternative to alcoholysis as a means of .pre: paring the monoesters, there may be employed direct esterification of the free fatty acids derived by hydrolysis, with :a suitable alcohol by heating a concentrated mixture of the reactants, generally in the presence of an esterification catalyst.

Broadly, solvent crystallization as a means of purification of a desired constituent is an old procedure. In the fractional crystallization "of any complexsystem, such as the mixtures specifiedherein, there are involved a numberof factors. Such a system exhibits the solubility of the individualcomponents in the particular solvent, and also the mutual solubility of the substances upon one another. While the former factor can be determined by actual solubilityexperiments upon the pure individual .substances, the vlatter factor is more complex and involves such considerations as mixed crystal formation, association between the components themselves or between the components and the solvent, etc.

If .palm oil itself were crystallized, sharp separation of the carotenoid content therefrom would be difficu lt and incomplete since the carotenoid compounds exhibit a marked aflinity for the trigly'cerides, and the triglycerides tend to assume the average characteristics of the fatty acids as generally two or three different acids of diverse nature and properties maybe combined within a single triglyceride molecule. By the'conversion of the triglycerides to the free fatty acids or their simple .alkyl esters, these latter considerations are-markedly reduced and eliminated for practical purposes.

Thus, it has been found that the carotenoidcontaining mixtures composed principally of the free :fatty acids or the alkyl esters and derived by hydrolysis .or alcoholysis respectively of the parent palm oil may Jae subjected to solvent crystallizationto attain an unusually sharp separae alcohols, esters, the hydrocarbons, halogenated hydrocarbons, ethers, etc. More specific examples of fatty solvents suitable for fractional crystallization herein are acetone, diethyl ketone, propane, butane, hexane, heptane, petroleum ether, trichloroethylene, propylene dichloride, chloroform, methyl alcohol, ethyl alcohol, carbon disulphide, methyl acetate, ethyl acetate, isopropyl acetate, monoethyl ether of diethylene glycol, etc. The solvents may be strongly or weakly polar, or non-polar in character. It is preferred however to use the normally liquid solvents such as acetone, methyl and ethyl acetate, etc. and

preferably those having a boiling point of not more than about 100 C.

The amount of inert solvent used to dissolve the fatty acid or fatty acid monoester composition may vary somewhat depending upon the particular selective solvent. The use of a concentration of the composition in the solvent of as low as about 2% is operable but a concentration of about 10% to about is preferred, withparticularly satisfactory results being attained within the range from about 10% to about 20% concentration.

After dissolving the mixture derived from palm oil in the solvent, the solution may be cooled to predetermined temperatures such that substantially all the fatty acids or fatty acid monoesters present therein are precipitated as a solid phase. The mixture may be separated by any means suitable for solid-liquid phase separation, including gravity, filtering, centrifugal force etc. The liquid or filtrate may again be cooled to the same or lower temperatures and additional solidified fractions may be separated therefrom.

Any number of cooling stages may be employed; however it is preferred to carry out at least two or three separation procedures. The separated matter if desired, may be further purified by dissolving it in fresh and/or a different solvent and reprecipitating the solid matter from solution by cooling. In addition, the separated matter may be washed one or more times with solvent at suitable temperatures.

In order to obtain a highly concentrated ca.- rotenoid fraction, the solution should generally be cooled to at least about 40 C., and preferably about -50 C. At these temperatures, substantially all the undesired constituents have been precipitated and separated thereby from the carotenoids in solution. Much unsaponifiable mat ter, substantially all the saturated fatty acids such as myristic, palmitic, and stearic, and a considerable percentage of the unsaturated fatty acids have crystallized out of solution at these temperatures.

The residual solution or filtrate is generally orange in color and contains substantially all the carotenoids in an unimpaired condition admixed with minor amounts of unsaturated acids. The unsaturates comprise chiefly linoleic acid and a minor amount of oleic acid. ..If"..desired, this solution may be recooled at lower temperaturesof'the orderxof about =50 C. and 70. C. whereupon yellow to orange-colored crystals are precipitated from solution. These crystals are converted to an orange colored oil at room temperature. This orange colored oil contains the carotene isomers as its chief constituents, the largest proportion being beta carotene, then alpha carotene and small amounts only of gamma carotene and other carotenoid pigments. 'Minor'amounts of unsaturatedfatty acids'comprising chiefly linoleic associated with a small proportion of oleic acid may be identified in the oil. Upon standing, the color of the orange oil is rapidly bleached by exposure to air and light to a very light greenish-yellow color. I

The solvent may be removed from the concentrate in any suitable manner. Where carotenoid crystals have been precipitated from solution, it is obvious that any conventional solid-liquid phase separationjmeans maybe employed as indicated supra. Where the carotenoid pigments are in solution, the solvent may be removed by evaporation. The solution may be heated under vacuum and preferably while passing in an inert gas to prevent injury to the'carotenoid sub-- stances during distillationof the solvent.

If desired, the various carotenoid substances in the concentrate may be isolated in any suitable manner. Fractional adsorption on alumi' num oxide or fullers earth may be used'satisfac torily. Chromatographic adsorption on calcium hydroxide or magnesium hydroxide from a solution of the carotenoids in a suitable solvent after I removal of any fatty acids are additional methods of purification. I

The following are additional specific examples designed to be illustrative to the nature of the invention:

1 Example I Red palm oil is saponified by the addition o f 'a 10% excess of potassium hydroxide, added as a 20% solution of KOI-I in ethyl alcohol, at 75-80? C.'in an atm-osphereof nitrogen. The saponification reaction mixture is acidified with dilute jsulphuric acid to convert the palm oil soaps to the corresponding free acids. After allowing the reaction mixture to settle, the aqueous phase/containing the excess sulphuric acid, glycerinefand alcohol is removed and the fatty acid phase is recovered for treatment.

50 grams of the palm oil acids are dissolved in two liters of acetone and cooled to *I0 C. for 20 minutes whereupon a light colored fractionprecipitates from solution. Themixture is then filtered to remove the solids, which are Washed with ml. of acetone previously cooled to -10 C. The washed solids are then almost white in color and comprise principally the more saturated fatty acids present in the original palm oil. The acids are washed with ether and weigh 17.0

grams. 7

The filtrate possessing the original orange color is recooled to 55 C. and the. precipitated fatty acids are separated by filtration. After washing with two 150 ml. portions of acetoneat 50 C, the solidified fatty acids are dried and weigh 22.0

grams. r

The crystallizataion procedure is repeated again on the filtrate at a temperature of -70 C. A small crop of yellow colored crystals separates which upon purification weighs 3.0 grams and is converted to an orange colored oil at room temperature. Upon standing, the col-or bleaches rapidly to a very light greenish-yellow color. Analysis of a. sample of the orange colored oil 7 discloss'th carotene isomers to'b the chief constituents (the largest proportion'being beta caro ten'e, then .alpha carotene and small-amounts only of gammacarotene) Minor amounts of unsaturated fatty acids comprising chiefly linoleic .acid associated with a smallproportion of oleic .acid may be identified in the concentrate.

Example II Red palm oil issaponified with a 10% excess of 50 .Baum aqueoussodium hydroxide solution at 80 C. under a reduced pressure-of fifteen inches of mercury in an atmosphere of nitrogen. The saponification reaction mixture is acidified with dilute sulphuric acid-and the resulting fatty acid phase containing the carotenoids is separated as indicated in Example I. i

The fatty acid layer is dissol-ved in sumcient petroleum ether to form a 10% solution. The solvent solution is cooledslowly to -C. and a solidified fraction which separates out-isremoved by filtration. The procedure is repeated upon the filtrateat C., and at C. The final filtrate has a deep-orange color and-the-petroleum ether solvent is-removed by evaporation. A sample of' the orange coloredsolvent-free liquid is subjected to chromatographic adsorption and indicates that the carotenoid content consists chiefly of the :alpha and'beta carotene isomers, with. minor amounts of other carotenoid pigments. 1 V

. ExampleIII "Palm oil is subjected to alcoholysis at 45 C. with inethanol --using 15 moles of .methanol per mole of palm oil in the presence of sodium hydroxide as a catalys't. At the completion of the reaction, "the alkaline catalyst is neutralized by the addition of dilute sulphuric acid. The reaction mixture is allowed to separate into two layers with .the-upperelayer containing the alkyl esters, alcohol, and the .unsaponifiablesincluding the carotenoids, and the lower layer comprising the glycerine and alcohol. The lower layer is removed and-the upper ester layer is washed and dissolved in sufficient petroleum ether to forma 20% solution.

The petroleum ether solution issubjeted to fractional crystallization at 10 C., 20 -C., an'd C. in the manner indicated in Example 1 whereby the saturated "fatty acidmonoesters-and the vast proportion of the unsaturated fatty acid monoesters are removed .by filtration. The solvent filtrate remaining after removing the fraction at minus 50 0. possesses an .orange color and is al'iighly concentrated carotenoid lfraction con- "taining minor amounts of methyl esters of unsaturatedfatty acid. The solvent'is evaporated under vacuum'andthe carotenoid concentrate is quickly placed in .a containerin an atmosphere of'nitrogen to prevent oxidationa'ndloss of caroterm. A sample of the concentrate is subjected to adsorption upon alumina whereby the carotene content .is substantially separated fromtheresidual" fatty acid monoesters, and 'dis'clo'singthereby in addition thepresence of comparatively "large amountsof alpha and betacarotenes.

Example IV The ethyl esters of :palm oil acids =arejpre- ;pared in the 'manner indicated -in Example .11 1 "using a 15 ;to 1 molar ratiozof .alcohol toijpalm -oil.- Upon completion of :the reaction ;and-'set- -tling, approximately .4 .molesof ethanol .per;m ole .of ethyl esters remain inrthe-upper layer of the reaction mixture.

The upper layer containing .the ethyl esters, the carotenoids and excess :a'lcohol :is subjected tofractional crystallization at -l0 -25" and 45" C. using the excess :ethyl alcohol as a solvent and diluent. The major proportion of the ethyl esters areprecipitated therebyizisolid ified form. After separating the precipitate. by filtration,- a final solidified orange-red fraction is crystallized from the filtrate at C. and comprises chiefly the desired carotenoid constituents admixture with a minor amount of unsaturated fatty acid ethyl esters.

Since certain changeszmay beimadein carryi out the above process without departing from the scope of the invention, it is intended that all :matter contained in the above description shall .be interpreted as illustrative and not in a limiting sense.

It is also to 'be understood that the following claims .are intended to cover all the eneric and specific features of the invention .herein described, and all statements of the SCODBOfqthB invention, which as a matter of language might be said to fall therebetween.

Having described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. The process of recovering a carotenoidaconcentrate from .a carotenoid-containing composition comprising chiefly .a fatty material of 'the group consisting of palm oil fatty acids and fatty acid monoesters of lower monohydric alcohols substantially free of triglycerides derived from the hydrolysis and alcoholysis of "palm .oil respectively, which comprises dissolvingsaidcomposition in an inert organic solvent, .coolingthe resultant solution to precipitate therefrom at least the major portion of the fatty material, separating the precipitated fraction vandrecovering .a carotenoid concentrate.

2. The process for preparing a carotenoid concentrate from a carotenoid-containing fatty composition of the group consisting of fatty acid mixtures and lower alkyl fatty acidmonoester mixtures derived from the hydrolysis and a1 coholysis of palm oil respectively, which ,comprises cooling a solution of .thesame in an inert organic solvent to at leastabout 40 C..to crystallize the majorpor-tion of the'fatty constituents therefrom, and separating the crystallized material "from the remainingcarotenoid-containing solution.

3. The process of claim 2 wherein the solvent is a normally liquid organic solvent.

4. The process of concentratingthe carotenoid content of palm oil which comprises ."convert ing said palm oil to a ,fatty material containing principally afatty constituent of the. group ,consisting of fatty acids :by hydrolysis and lower alkyl fatty :acid monoesters .by alcoholysis respectively admixed with the carotenoid c onstituents and substantially free of triglycerides dissolving :said fattymaterial in anzinert organic :solvent to form a solution, :lowering the temperature-of the resulting solution to crystallize at leastxarmajorportion of the-fattyconstituents therefrom, separating saidcrystallizedzfattyaconstituents and recovering a carotenoid .aconcentrate from fthe residual solution.

'5. *The process -.of claims wherein the solvent is a normally liquid organicisolvent.

i6. Thepro'c'ess of :re'coveringa carotenoid fraction 'from palm oil which comprises :subjecting said palm oil to alcoholysiswith=ailowerzmonohydric' .alcohol "to. produce '23, creactionza-mixture containing chiefiy fatty acid esters of said monohydric alcohol admixed with the carotenoid substances, dissolving said fatty acid monoe'sters and carotenoids in an inert organic solvent, lowering the temperature of the resulting solution to a predetermined point to cause solidification of at least the major portion of said fatty acid monoesters, separating the solidified fraction from the remaining solution, and recovering a highly concentrated carotenoid fraction.

7. The process of recovering a carotenoid concentrate from palm oil which comprises subjecting said palm oil to alcoholysis with a lower monohydric alcohol to produce a reaction mixture containing chiefly fatty acid esters of said monohydric alcohol admixed with the carotenoid substances and substantially free of triglycerides, dissolving said fatty acid monoesters and carotenoids in an inert organic solvent, lowering the temperature to at least minus 40 C. to precipitate a solidified fraction, separating the solidified fraction, and recovering a highly concentrated carotenoid fraction from the remaining solution.

8. A method for the recovery of a carotenoid concentrate from palm oil comprising alcoholizing said palm oil with a lower monohydric alcohol to produce a reaction mixture containing principally fatty acid monoesters admixed with the carotenoids, subjecting said mixture to fractional crystallization with an inert organic solvent to remove the major portion of the fatty acid monoesters, and recovering a carotenoid concentrate.

9. A method for the recovery of a carotenoid concentrate from palm oil comprising hydrolyzing said palm oil, to produce a reaction mixture containing principally fatty acids admixed with the carotenoids, subjecting said mixture to fractional crystallization with an inert organic solvent to separate the major portion of the fatty acids from the carotenoids and recovering a carotenoid concentrate thereby.

10. A method for the recovery of a carotenoid concentrate from palm oil comprising hydrolyzing said palm oil by saponification and acidification to produce a reaction mixture containing principally fatty acids admixed with the carotenoids, subjecting said mixture to fractional crystallization with an inert organic solvent to separate the major portion of the fatty acids from the carotenoids, and recovering a carotenoid concentrate.

11. A process for recovering a carotenoid concentrate from palm oil which comprises saponi fying said palm oil with an alkaline saponifying agent at a temperature of less than about C. to convert triglycerides of palm oil to soaps, acidifying said soaps to free fatty acids containing carotenoid pigments of palm oil in admixture therewith, dissolving the resulting fatty acidcarotenoid mixture in an inert organic solvent, lowering the temperature of said mixture to crystallize at least a major portion of the fatty acids therefrom, separating said crystallized fatty acids and recovering a carotenoid concentrate.

12. The process of claim 11 wherein fatty acids are crystallized at temperatures of at least -40 C.

ARTHUR IRA GEBHART.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,318,747 Buxton May 11, 1943 2,460,796 Eckey Feb. 1, 1949 FOREIGN PATENTS Number Country Date 433,930 Great Britain Aug. 22, 1935

Claims (1)

11. A PROCESS FOR RECOVERING A CAROTENOID CONCENTRATE FROM PALM OIL WHICH COMPRISES SAPONIFYING SAID PALM OIL WITH AN ALKALINE SAPONIFYING AGENT AT A TEMPERATURE OF LESS THAN ABOUT 150* C. TO CONVERT TRIGLYCERIDES OF PALM OIL TO SOAPS, ACIDIFYING SAID SOAPS TO FREE FATTY ACIDS CONTAINING CAROTENOID PIGMENTS OF PALM OIL IN ADMIXTURE THEREWITH, DISSOLVING THE RESULTING FATTY ACIDCAROTENOID MIXTURE IN AN INERT ORGANIC SOLVENT, LOWERING THE TEMPERATURTE OF SAID MIXTURE TO CRYSTALLIZE AT LEAST A MAJOR PORTION OF THE FATTY ACIDS THEREFROM, SEPARATING SAID CRYSTALLIZED FATTY ACIDS AND RECOVERING A CAROTENOID CONCENTRATE.