US2345097A - Process for treating fatty oils - Google Patents

Description

meta Ma 2a, 1944 Loran'O. Buxton, Belleville, N. 1.,

minor-to National Oil Products Company, Harrison, N. 1., ,a corporation of New Jersey No Drawing. Application December 11, 1040,

' Serial N0. 369,552

13 Claims. (01. rev-s1) This invention relates to the recovery of valuable fractions from fatty oils, more particularly to the preparation of concentrated fat-soluble vitamin compositions containing the vitamins predominantly in the ester form.

As. is well known to those skilled in the art, considerable work has been done on the distillation of fat-soluble vitamin-containing oils under a high vacuum to recover valuable vitamin constituents from the oils at temperatures sufilciently low that the vitamins remain substantially un-' destroyed during the distillation. However, the processes thus far developed possess several disadvantages. In the flrst place, it has been found that free fatty acids, nitrogenous compounds, and odoriierous and bad-tasting constituents, which are contained in practically every naturally-occurring fat-soluble vitamin-containing oil, tend to distill over with the fat-soluble vitamins. As a result, the distillates obtained by the proposed processes contain many of the undesirable constituents of the oil concentrated therein, with the inevitable result that in spiteof the increased vitamin potency of these fractions, their odor and taste, as well as their free fatty acid content, have rendered them somewhat undesirable to the trade. 1

It has also been proposed to distill vegetable or animal oils under a high vacuum in order to obtain products of value in the paint and varnish industry. However, in order to suitably obtain such products, the oils usually must be subjected to aqueous alkali treatment to remove break constituents, the presence of which interferes with the distillation; this alkali treatment generally destroys some of the valuable antioxidants present in the oil, thus preventing their utilization.

In carrying out experiments relating to the solvent extraction of fat-soluble vitamin-contaim ing oils, I have made the surprising observation that the treatment of these oils with certain types of organic'solvents yields valuable highly potent extracts containing a portion of the iat=soluble vitamins and the bulk of the antioxidants concentrated therein. Thus I have found that fatsoluble vitamin-containing oils containing at least 2% unsaponiiiable matter may be subjected to extraction with hot methanol or ethanol and the mass then cooled, whereby an alcoholic layer separates containing dissolved therein an oil having a much higher vitamin potency than the original oil; this process is more fully described and claimed in my copending application Serial No. 321,409, filed February 29. 1940. Other experiments carried out by me in collaboration with other workers have shown that highly potent fatsoluble vitamin extracts may also be obtained by contacting a fat-soluble vitamin-containing oil with a suitable solvent at a temperature such that at least the'maior portion oi the oil is mis- 'cible with the solvent and then cooling the mixture, whereby a solvent layer containing the desired extract separates. Among the solvents which were found-to be particularly suitable for use in this latter process are those listed in the table below:

Table I Aliphatic and alicyclic monohydroxy alcohols 7 containing from 3 to 6 carbon atoms.

2. Esters of said alcohols with aliphatic monocarboxylic acids, said esters containing not more than 8 carbon atoms.

3. Aliphatic and alicyclic aldehydes containing not more than 6 carbon atoms.

4. Aliphatic ketones containing not more than 6 carbon atoms.

tures above room temperature and partially immiscible therewith at temperatures substantially below room temperature; experiments in this connection have shown that solvents of this c may be used generally in the process herelnabove described. This process is disclosed and claimed in copending application Serial No. 343,558, filed July 2, 194.0, under the name of Dombrow. l have also found that solvents of the type dis closed in this latter application are capable of removing highly effective antioxidanm and sterois from fatty materials with which they are associated; the process for the recovery of such antioxidants is disclosed in my copending application Serial No. 351,909, filed August 8, 19%.

An object of this invention is to provide a process whereby fatty oils may be treated so to recover the valuable constituents therefrom with the greatest emciency.

A more specific object of this invention is to provide a fat-soluble vitamin-containing oil solvent extraction procedure yields oil at a temperature substantially above room temperature with a solvent selected from the group consisting of methanol, ethanol and liquid aliphatic compounds miscible with fatty oils at temperatures above room temperature and partially immiscible with fatty oils at temperatures substantially below room temperature and cooling the mass to a temperature substantially below room temperature as disclosed in the aforesaid patent applications, are of such a nature that they may be subjected to high vacuum distillation so as to obtain highly valuable products containing practically no undesirable constituents. The preferred embodiment of my invention involves contacting a fat-soluble vitamin-containing oil, particularly an 011 containing vitamins A and/or D, with a solvent of the type above set forth at a temperature above room temperature, cooling the mass to a temperature substantially below room temperature, separating the solvent layer from the residual oil, heating'tlie residual oil to remove any remaining solvent therefrom, and then subjecting the residue to high vacuum distillation. The distillates thus obtained contain substantially no free fatty acids or nitrogenous compounds, and, in addition, contain practically none of the odoriferous and bad-tasting constituents which lend the characteristic odor and taste to naturally-occurring fat-soluble vitamin-containing oils; furthermore, the vitamins concentrated in these distillates are practically entirely in the ester form. My process possesses notable advantages over processes heretofore developed for. the recovery of fat-soluble vitamin esters from fat-soluble vitamin-containing oils. In the first place, as hereinabove mentioned, the preliminary a highly potent fat-soluble vitamin extract. In the second place, the residue from this extraction, when distilled in accordance with my invention, furnishes a substantially odorless and tasteless fat-soluble vitamin-containing oil, which product may be employed widely from human or animal consumption. As a result, my process permits the utilization of the fat-soluble vitamins contained in oils of the type of fish liver oils in a most efficient and economical manner. Furthermore, the application of the process of this invention to the treatment of fatty oils of the type of vegetable and animal oils permits the recovery of valuable antioxidants and sterols in the solvent extract and the subsequent production of valuable fractions by high vacuum distillation of the residues, thereby utilizing all the valuable constituents of these oils..

The oils which may be treated in accordance with this invention may be any fatty oil or mixture of fatty oils. I prefer to apply my process to the treatment of fat-soluble vitamin-containing oils, 1. e. oils containing appreciable uantities of vitamins A, D, E or K, particularly oils containing vitamins A and/ or D; as examples of such oils there may be mentioned cod liver oil, shark liver oil, tuna liver oil, halibut liver oil, mackerel liver oil, ling cod liver oil, sole liver oil, spear fish liver oil, sword fish liver oil, palm oil, Wheat germ oil, corn germ oil, rice germ oil, alfalfa seed oil, tomato seed oil, etc. These oils, as is well known, all contain considerable amounts of one or more of the fat-soluble vitamins. In addition, however, these oils generally contain ingredients which lend them a rather unpleasant taste and odor and in many cases also contain considerable proportions of free fatty acids and nitrog enous compounds. However, other fatty 011s which do not contain fat-soluble vitamins may also be treated; thus oils such as soybean oil, wheat bran oil, corn oil, oat oil, rye oil, olive oil, sesame oil, cottonseed oil, palm kernel oil, coconut oil, rice oil, linseed oil, oiticia oil, teaseed oil, perilla oil, celery seed oil, flax seed oil, groundnut oil, hemp seed oil, kapok oil, mustard seed'oil, rape seed oil, poppy seed oil, sunflower seed oil, pumpkin seed oil, melon seed oil, peanut oil, grape seed oil, peach kernel oil, egg oil, whale oil and the like, may be processed by this invention.

The first step of my invention involves contacting the oil to be treated at a temperature above room temperature with a solvent selected from the group consisting of methanol, ethanol and solvents miscible with fatty oils at temperatures above room temperature and partially immiscible therewith at temperatures substantially below room temperature, particularly those of the type listed in Table I above. Thus in addition to methanol and ethanol, solvents such as n-propyl alcohol, isc-propyl alcohol, n-butyl alcohol, namyl alcohol, isoamyl alcohol, secondary amyl alcohol, furfuryl alcohol, allyl alcohol, diacetone alcohol, ,B-hydroxy ethyl acetate, methyl formate, ethyl formate, ethyl acetate, methyl acetate, isopropyl acetate, glycol diformate, glycol diacetate, methyl levulinate, ethyl levulinate, methyl aceto acetate, ethyl aceto acetate, methyl furoate, vinyl acetate, furfural, propionaldehyde, crotonaldehyde, acetone, methyl ethyl ketone, acetonyl acetone and propylene chlorhydrin may be used. I have found that methanol and ethanol may be most effectively used with oils containing more than 2% unsaponifiable matter; the remaining solvents may be employed with advantage with practically any fatty oil, isopropanol being particularly useful by reason of its efficiency, cheapness and ready availability. Mixtures of the above solvents maybe used as well as solvents of the above types diluted with small amounts of water to suitably alter the solubility of certain of the constituents of the oil in the solvent. The ratio of solvent to oil should be greater than one and should preferably be about 4 to 50 of solvent to one of oil.

After the oil has been thoroughly contacted with the solvent so as to extract the soluble constituents therefrom, the mass is cooled to a temperature below room temperature, i. e. within the range of 25 C. to '70 C. and preferably to a point withinthe range of 0 C. to -18 C. Upon cooling, two layers form, one comprising a solution of certain constituents of the oil in the solvent and the other comprising the solventinsoluble ingredients of the oil; these layers may then be separated, the residual layer re-extracted, if desired, and the several extracts combined. If a crude fat-soluble vitamin-containing oil is being treated in accordance with the preferred embodiment of this invention, the extract contains dissolved therein a portion of the fatsoluble vitamin present in the original oil, including practically all of those existing in alcohol form, together with the bulk of the free fatty acids, some of the sterols, nitrogenous compounds, odor and taste-forming constituents and antioxidants present in the oil. The extract from a fatty oil containing substantially no fat-soluble vitamins usually comprises the antioxidants and break constituents, if any, of the oil, together with the fatty acids, some of the sterols, nitrogenous compounds, and odor and taste-forming ingredients. The residues from these extractions are substantially devoid of free fatty acids, ni-

trogenous compounds, odor and taste-forming constituents and antioxidants; they contain the majority of the glycerides originally present in the oil and, if a fat-soluble vitamin-containing oil has been extracted, substantial amounts of the fat-soluble vitamin esters originally present in the oil. They usually also contain small amounts of solvent, which is preferably removed by evaporation. Further details with respect to the extraction step of this invention may be found in the copending applications hereinabove referred to.

The residues from the extractions above described may then in accordance. with the process of this invention be subjected to high vacuum distillation. This distillation is preferably carried out by continuously flowing a relatively thin film of the oily material over a heated surface at pressures below about 0.1 mm., preferably in the neighborhood of about 0.001 mm., the heated surface being maintained at a predetermined temperature such that a distillate of the desired characteristics distills from the oil and is condensed; the condensing surface may be anywhere from 1 inch to 4 feet from the surface of the material being distilled. Undesired fractions more volatile than the fractions to be recovered may be removed from the oily material in a stripping column prior to the recovery of the desired distillate; furthermore, it is desirable to thoroughly degas the oily material prior to distillation in order to avoid frothing. In order to achieve a relatively complete and clean-cut'separation of the desired fraction from the oily material, it is generally advisable to adjust the temperature and rate of flow so that relatively small cuts of the desired fraction are recovered; the residues may then be redistilled in the same manner as many times as required to recover the remainder of the desired fractien. However, in

some cases redistillation of the residues may not be necessary.

As hereinabove stated, the preferred embodiment of my invention involves the hignvacuum distillation of the residue obtained by the solvent extraction of a fat-soluble vitamin-containing oil, particularly an oil containing vitamins A and/or D, to obtain a fraction having the fatsoluble vitamin esters concentrated therein. Thus, for example, the residue obtained by the solvent extraction of a fishliver oil as above described is particularly suitable for the purposes of this invention. The vitamin A and D esters present in such residues volatilize from the oil at temperatures between about 140 C. and about 250 (3., provided the pressure is-below about 0.1 mm. Hence distillation of such fish liver oil residues is most suitably carried out by first stripping the residue of the fraction distilling below about 140 C. and then continuously fiow= ing the remainder of the material over a heated surface maintained at'a temperature of about 250 C., the pressure being in the neighborhood of about 0.001 mm. In many cases it will be found-that residues from the solvent extraction of a fish liver 011 do not contain any appreciable quantities of glycerides distilling under 250 C.; in such cases the vitamin esters are practically the only components of the distillate, and since these esters form a relatively small percentage of the total oil being distilled, the volume of distillate is sometimes so small as to prevent eflicient recovery of the desired esters. Hence in such instances it has been found advisable to add to the material being distilled a natural or that the distillate containing the vitamin esters will be of such a volume as to permit emcient recovery. The distillation is most advantageously run byadjusting the temperature of the heating surface, and rate of flow of oil thereover, so that a distillate in an amount equivalent to about 5% to 10% of the oil being distilled is recovered; the residue from this distillation may then be redistilled as many times as required to recover substantially all of the vitamin A and D esters. Because of the relative instability of the vitamin esters at elevated temperatures, apparatus designed to rapidly heat the oil to the desired temperature and then quickly cool the condensate and residue is preferably employed.

If a mixture of the vitamin A and D esters is desired, the temperature at which the distillation is carried out is maintained in the neighborhood of about 250 C. and the distillates thus obtained are condensed and combined. However, if a partial separation of the vitamin A and D esters is desired, the oily material stripped of the fraction distilling below C. is distilled at a temperature in the neighborhood of about 205 C.; the distillates thus obtained will be found to contain a greater proportion of vitamin A ester than the distillates recovered as above described. A fraction rich in vitamin Dester may then be recovered by subjecting the residue from which the vitamin A ester has been removed to distillation at about 250 C.

Distillation of residues obtained by the solvent extraction of oils containing substantially no fat-soluble vitamins in accordance with this invention possesses the important advantage that the solvent extraction step removes antioxidants and break constituents, thereby eliminating from the oils those constituents which would normally cause difficulties during the course of the high vacuum distillation. As hereinabove pointed out, the antioxidant fraction removed possesses great utility, so that this invention aifrom the oil without destroying their valuable properties. My invention thus permits the most efiicient and economical utilization of all the valuable ingredients of these oils.

As will be appreciated by those skilled in the art, certain modifications in the vacuum distillation step of my invention may be made. For example, various indicators having the properties of distilling at temperatures approximating those of the desired fractions may be included in the oil, so that the presence of the desired fractions in the distillate may be distinguishable and the distillation regulated accordingly. Inert oils may be flowed over the condensing surface in order to remove therefrom small quantities of the desired fractions condensing thereon. Furthermore, since the solvent extraction steps hereinabove referred to remove the natural antioxidants contained in fat-soluble vitamin-containing oils, it maybe desirable,when distilling residues obtained by the extraction of fat-soluble vitamin-containing oils, to .add thereto oil-soluble antioxidants, particularly those distilling within the same range as the fat-soluble vitamin esters; I have found that the antioxidants extracted from vegetable oils or mixtures thereof by the process described in application Serial No. 351,909 and from which the phosphatides have been removed by crystallization from acetone, are particularly suitable for addition to the vitamin oils being distilled in accordance with this invention, since the antioxidants contained therein distill over with the desired vitamin esters. Other modifications may also be introduced without departing from the scope of this invention.

The fat-soluble vitamins contained in the distillates obtained by the practice of the preferred embodiment of this inventionexist practically entirely in the ester form; these dlstillates are substantially odorless and tasteless and contain no free fatty acids or nitrogenous compounds. Furthermore, these distillates contain practically none of the highly unsaturated glycerides originally present in the fat-soluble vitamin-containing oil, since the solvent extraction step removes the bulk of these compounds; hence my distillates tend to be more stable to oxidation than similar distillates heretofore produced which usually contained considerable amounts of such glycerides. Thus it will be evident my distillates are particularly suitable for human or animal consumption.

It will be evident from the above description that my invention provides a process capable of utilizing valuable constituents contained in the oils of the type above mentioned to the utmost advantage. Because of the many advantages inherent in my process, it will undoubtedly be of great interest to those engaged in the treatment of fatty oils of all types.

Since certain changes in carrying out the above process and certain modifications in the compositions which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A process for treating fatty oils to recover valuable constituents therefrom, which comprises contacting a fatty oil at a temperature above room temperature with a solvent selected from the group consisting of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms, esters of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms with aliphatic monocarboxylic acids, said esters containing from 2 to 8 carbon atoms, aliphatic and alicyclic aldehydes containing from 3 to 6 carbon atoms and aliphatic ketones containing from 3 to 6 carbon atoms, cooling the mass to form two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. to recover valuable constituents therefrom.

2. A process for treating fat-soluble vitamincontaining oils to recover valuable constituents therefrom, which comprises contacting a fatsoluble vitamin-containing oil at a temperature above room temperature with a solvent selected from the group consisting of aliphatic and ali-,

cyclic monohydroxy alcohols pontaining from 1 to 6 carbon atoms, esters of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms with aliphatic monocarboxylic acids, said esters containing from 2 to 8 carbon atoms, aliphatic and alicyclic aldehydes containing from 3 to 6 carbon atoms and aliphatic ketones containing from 3 to 6 carbon atoms, cooling the mass to form two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. to recover a fraction rich in fat-soluble vitamin esters.

3. A processs for treating lat-soluble vitamincontaining oils to recover valuable constituents therefrom, which comprises contacting a fish liver oil at a temperature above room temperature with a solvent selected from the group consisting of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms, esters of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms with allphatic monocarboxylic acids, said esters containing from 2 to 8 carbon atoms, aliphatic and alicyclic aldehydes containing from 3 to 6 carbon atoms and aliphatic ketones containing from 3 to 6 carbon atoms, cooling the mass to form two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. to recover a fraction rich in fat-soluble vitamin esters.

4. A process for treating fat-soluble vitamincontaining oils to recover valuable constituents therefrom, which comprises contacting a fish liver oil 'at a temperature abov room temperature with a solvent selected from the group consisting of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms, esters of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms with aliphatic monocarboxylic acids, said esters containing from 2 to 8 carbon atoms, aliphatic and alicyclic aldehydes containing from 3 to 6 carbon atoms and aliphatic ketones containing from 3 to 6 carbon atoms, cooling the mass to form two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. and within the temperature range of 140 C. to 250 C. to recover a fraction rich in fat-soluble vitamin esters.

5. A process for treating fat-soluble vitamincontaining oils to recover valuable constituents therefrom, which comprises contacting a vitamin A and D containing oil at a temperature above room temperature with a solvent selected from the group consisting of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms, esters of aliphatic and alicyclic monohydroxy alcohols containing from 1 to 6 carbon atoms with aliphatic monocarboxylic acids, said esters containing from 2 to 8 carbon atoms, aliphatic and alicyclic aldehydes containing from 3 to 6 carbon atoms and aliphaticketones containing from 3 to 6 carbon atoms, cooling the mass to form'two layers, separating the 'solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. and collecting one fraction distilling between 140 C. and 205 C. and another distilling between 205 C. and 250 C.

6. A process of treating fat-soluble vitamincontaining oils, which comprises admixing a fatsoluble vitamin-containing oil with a solvent comprising chiefly isopropanol, heating the mass to effect substantially complete miscibility of the oil in the solvent, cooling the mass to produce two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. to recover a fraction rich in fat-soluble vitamin esters.

7. A process of treating fat-soluble vitamincontaining oils, which comprises admixing a fatsoluble vitamin-containing oil with a solvent comprising chiefly isopropanol, heating the mass to effect substantially complete miscibility oi the the temperature range of 140 C. to 250 C. to

recover a fraction rich in fat-soluble vitamin esters.

8. A process 01 treating fish liver oils, which comprises admixing a flsh liver oil with a solventcomprising chiefly isopropanol, heating the mass to eflect substantially complete miscibility of the oil in the solvent, cooling the mass to produce two layers, separating the solvent layer from the oil layer and subjecting the'oil layer to distillation at a pressure below 0.1 mm. and within the temperature range of 140 C. to 250 C. to recover a fraction rich in fat-soluble vitamin esters.

9. A process of treating fat-soluble vitamincontaining oils, which comprises admixing a fatsoluble vitamin-containing Oil with a solvent comprising chiefly isopropanol,'heating the mass to eflect substantially complete miscibility oi the oil in the solvent, cooling the mass to a temperature within the range 0 C. to -l8 C. to produce two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. and within the temperature range of 140 C. to 250 C. to recover a fraction rich in tat-soluble vitamin esters. 10. A process of treating vitamin A and D containing oils, which comprises admixing a vitamin A and D containing oil with a solvent comprising chiefly isopropanol, heating the mass to eflect substantially complete miscibility or the oil in the solvent. cooling the'mass to a temperature within the range of 0 C. to -l8 C. to produce two layersfiseparating the solvent layer from the oil layer and subjecting the oil and within the temperature range of 140 C. to 250 C. to recover a fraction rich in rat-soluble vitamin esters.

11. A. process of treating vitamin A and D 5 containing oils, which comprises admixing a vitamin A and D containing oil with a solvent comprising chiefly isopropanol, heating the mass to eflect substantially complete miscibility oi the oil in the solvent, cooling the mass to a temperature within the range of 0 C. to -l8 C. to produce two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. and collecting one fraction distilling between 140 C. and 205 C. and another distilling between 205 C. and 250 C.

a 12. A process of treating fat-soluble vitamincontaining oils, which comprises admixing a fatsoluble vitamin-containing oil with a solvent comprising chiefly methanoLheating the mass to effect partial miscibility or the oil in the solvent, ,cooling the massto produce two layers,

separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. and within the temperature range of 140 C. to 250 C. to recover a fraction rich in fat-soluble vitamin esters.

13. A process of treating rat-soluble vitamincontaining oils, which comprises admixing a fatsoluble vitamin-containing oil with a solvent comprising chiefly diacetone alcohol, heating the mass to effect substantially complete miscibility of the oil in the solvent, cooling the mass to produce two layers, separating the solvent layer from the oil layer and subjecting the oil layer to distillation at a pressure below 0.1 mm. and within the temperature range of C. to 250 C. to recover a fraction rich in'tat-sol'uble vitamin esters.

4o LORAN O. BUXTON.

layer to distillation at a pressure below 0.1 mm.