US2396681A - Process of producing natural antioxidants - Google Patents

Description

Patented Mar. 19, 1946 PROCESS OF PRODUCING NATURAL- ANTIOXIDANTS Loran 0. Buxton, Maplewood, N. J., assignor to National Oil Products Company, Harrison, N. J a corporation of New Jersey No Drawing. Original application February 20,

Serial No. 431,700. Divided and this application December 13, 1944, Serial No. 568,075

8 Claims.

This invention relates to the production of antioxidants and to the stabilization of oxidizable organic Substances, primarily those of an oily or fatty nature.

It is well known in the art that many oxidizable organic substances, e. g., oils, fats and waxes containing fatty acid radicals, as well as soaps thereof, tend to be detrimentally affected by exposure to atmospheric conditions for prolonged periods of time. For example, many oils and fats tend to develop considerable rancidity and undersirable tastes and odors upon prolonged exposure to air. This instability of oils and fats tends to be accentuated by conventional refining processes since in many cases the refining treatment destroys or removes the natural antioxidants contained in such substances. This characteristic instability is particularly undesirable in connection with fatesoluble vitamin-containing oils since theseoils not only show the typical tendency to become rancid upon exposure to air but also tend to lose a considerable portion of their valuable vitamin activity. Other oxidizable organic substances manifest their characteristic instabilities in different fashions but in practically every case their instability is highly undesirable.

As a result of the instability shown by many oxidizable organic substances, many attempts have been made to increase the resistance of ,these substances to the action of oxidizing influences. For example, it has been proposed to stabilize oils and fats by adding certain crude vegetable oils thereto, the theory being that since the crude vegetable oils suggested for use contain natural antioxidants, these antioxidants would serve to stabilizethe oils and fats. This proposal has, however, not met with any particular success because of the fact that since the vegetable oils do not contain very high percentages of the antioxidants, disproportionately large amounts of the oils have to be added to the substances to be stabilized in order to achieve the desired anti- A oxidant effect. Several proposals have been advanced designed to recover valuable fractions from vegetable oilsbut there has been no important success achieved along these lines with regard to the production of effective antioxidants therefrom. As a matter of fact, the art has generally believed-that the vegetable meals, not the. oils expressed therefrom, were the most suitablesource of antioxidants and has turned away from the idea of recovering antioxidants from such oils.

It was been suggested'that solvents, such as ethyl alcohol, would be capable of extracting cfiective antioxidants from oil-free vegetable meals. This proposal has several disadvantages. In the first place, the antioxidants extracted from the meals are generally not completely oil-soluble so that in some cases it is not possible to form completely homogeneous mixtures of these antioxidantsvwith substances such as oils and fats. In the second place, the antioxidants extracted from vegetable meals may have extremely dark colors and unpleasant odors and are generally obtained in very poor yields. The result of these disadvantages has been that the suggested method has not met with any substantial degree of commercial success.

It has also been proposed to recover antioxidants from vegetable oils by saponifying the oils, separating the unsaponifiable portions by successive extractions and fractionations. This proposal has likewise been commercially unsuccessful because it entails the destruction by saponification of the valuable vegetable oils, thereby rendering the process highly ineconomical, and because the saponification destroys the antioxidant properties of certain of the materials contained in the oils; moreover, the necessity for carrying out a number of extraction and fractionation steps is clearly disadvantageous.

Because of the many disadvantages inherent in prior processes for the production of antioxidants there is still a considerable demand in the industry for a simple, economical and efiective method for preparing antioxidants which will accomplish the desired results. Furthermore, because of the tremendous recent development in the production and use of fat-soluble vitamincontaining oils, the need for such antioxidants has become particularly acute due to the well known instability of vitamins contained in such oils.

It is an object of this invention to provide a simple and economical process for the production of highly effective antioxidants.

A specific object of this invention is to provide naturally occurring antioxidants capable of stabilizing fat-soluble vitamin-containing oils.

Other objectsof the invention will in part be obvious and will in part appear hereinafter.

I have discovered that highly active antioxidant compositions may be prepared from fatty materials containing natural antiqxidants by treating such materials with highly polar solvents which are substantially immiscible with the fatty materialslat room temperature or at temperatures above room temperature. I have found, contrarygto all expectations. that although the fatty materials themselves are immiscible with the polar solvents at room temperature or above, the natural antioxidants contained therein, or a substantial portion thereof, are soluble in the solvents. My discovery thus provides a simple, effective means of preparing highly p0.- tent natural antioxidant concentrates since merely by extracting a natural antioxidant-comtaining fatty material at about room temperature (i. e., about C. to 30 C.) with a highly polar solvent immiscible therewith, the natural antioxidants contained in the fatty material become concentrated in the solvent. The fatty material and the solvent are readily separated, e. g., by decantation, centrifugation, etc., and the natural antioxidants easily recovered from the solvent, e. g., by vacuum distillation of the solvent, leaving as'a residue a very active antioxidant fraction. 'My discovery is particularly applicable to the recovery of antioxidants from fatty oils such as vegetable and fish oils since the solvent extraction of such materials with highly polar solvents immiscible therewith yields products containing antioxidants in extremely active condition. I have further found thatthe extracts recovered from fatty materials may be blended with oxidizable organic substances to form mixtures extremely resistant to deteriorative oxidation. This invention is primarily concernedwith the stabilization of oxidizable organic substances of an oily or fatty nature since m antioxidants may be easily blended with such substances to form completely homogeneous, stable mixtures.

A preferred embodiment of my invention involves the stabilization of fat-soluble vitamincontaining oils since the addition of my extracts to such oils not only prevents the development of undesirable rancidity and discoloration but also stabilizes the vitamin content of the oils so that there is relatively little destruction of either the vitamin A or vitamin D contained in the oils even after prolonged exposure to atmospheric conditions. My novel process has the additional advantage that the residual fatty materials from which the antioxidants have been extracted are more valuable than the fattymaterials originally treated since a certain amount of refining takes place due to a substantial removal of color and odor along with constituents responsible for the production of "break. Thus my invention not only yields valuable antioxidants but also produces refined fatty materials suitable for a wide variety of purposes. The yields obtained in accordance with my process are excellent and the solvents employed are all readily available and comparatively inexpensive. As 'a result, this novel process for the preparation of antioxidants is extremely economical.

The fatty materials from which the antioxidants are extracted in accordance with this invention may be any fatty materials containing naturally occurring antioxidants, or mixtures of such fatty materials; preferably, crude oils containing such antioxidants are employed. The term fatty material is used throughout the specification and claims to include oils, fats and waxes containing fatty acid radicals. There are many such materials containing natural antioxidants known to the art. Thus, vegetable oils andpfats such as soybean oil, wheat germ oil,

seed oil, perilla oil alfalfa seed oil, celery seed oil, flax seed oil, hemp seed oil, kapok oil, mustard seed oil, rape seed oil, poppy seed oil, sunfiower seed oil, pumpkin seed oil, melon seed oil, peanut oil, and the like, .may be treated. Another group of fatty materials which may be employed is the fish liver oils such as 'cod liver oil, tuna liver oil, halibut liver oil, shark liver oil, etc., as well as other marine oilssuch as menhaden oil, herring oil and sardine oil. Other oils which may be treated in accordance with the present invention are tomato seed oil, grape seed oil, peach kernel oil, egg oil and whale oil. I prefer to produce my antioxidants from vegetable oils and in the detailed description hereinafter given particular reference will be made to the treatment of such oils; however, it is to be understood that other fatty materials may be used if desired.

The solvents which may be used in carrying out the process'of the invention include methanol and ethanol, either of which may contain any suitable quantity of water or no water at all. Moreover,'a mixture of these two solvents may be used. A solvent sold under the trade-mark Solox by U. S. Industrial Chemicals,'1nc. was found to be quite eificacious in practicing this invention. The natural antioxidants which it is desired to extract from the fatty materials are soluble in methanol and ethanol at room tem-.

perature whereas the fatty materials themselves are immiscible therewith or relatively so.

In carrying out the extraction of the antioxidants from the oils with which they are associated, the oil to be treated is first mixed with the particular solvent to be employed. The relative proportion of oil to solvent may vary widely; the ratio of solvent to oil should be greater than one and, preferably two to fifty parts of solvent to one part of oil. If desired, the solvent-oil mass may corn germ oilfcorn oil, oat oil, wheat bran oil, rye oil, olive oil, sesame oil, cottonseed oil. palm oil, cocoa butter, palmkernel oil, coconut oil, rice bran oil, rice germ oil, linseed oil, oiticia. oil, teabe warmed to a temperature slightly or substantially above room temperature. By so doing, it is sometimes possible to obtain somewhat moreintimate contact of the solvent with the fatty material and thereby obtain a more eflicient and complete extraction of the natural antioxidants. The solvent solution and the fatty material may then be separated from each other at the elevated temperature or th mixture may first be allowed to cool to room temperature before completing this step of the process. The extraction is preferably carried out in an atmosphere of inert gas.

The antioxidant fraction extracted from the oil may be recoveredin any suitable manner. A the solvent and the oil are immiscible at room or at temperatures substantially above room temperature, they may be separated by decantationj centrifugation or any other suitable means. The oil will generally be found to be somewhat lighter in color than originally and in many cases will have lost some of its original characteristic odor. Furthermore, in most cases it will be found that materials responsible for producing break" have been removed from the oil by the extraction. Thus the oil which has been extracted by the process of this invention may be used for a' 1 thesterols may be removed; however, these steps are not essential since the glycerides and sterols do not inhibit the antioxidant properties of the extract. If the extract contains an excessive amount of free fatty acids, these are preferably removed by treatment with alkali in a hydrocarbon or chlorinated hydrocarbon solvent medium or by other suitable methods. The extract ordinarily possesses the characteristic odor and color of the oil from which it is obtained and is generally slightly more viscous than the original oil. Tests carried out on vegetable oil extracts indicate that the iodine values of the extracts are substantially lower than those of the original oils. If a vitamin-containing fish liver oil is employed in H the practice of the present invention, it will be found that the extract contains a considerable Portion of the vitamins concentrated therein.

My novel antioxidants may be employed for the stabilization of all types ofoxidizable organic substances, particularly those of a fatty nature, i. e., fatty oils, fats, waxes, soaps, vitamin concentrates, etc. Thus oils and fats of animal, vegetable or fish origin, such as cod liver oil, tuna liver oil, shark liver oil and other fish liver oils, as well as vitamin concentrates or vitamin-containing fractions obtained from such oils; corn oil, cotton seed oil, soybean oil and other vegetable oils; fats such as butter, margarine, lard, hydrogenated shortenings, palm oil, etc.; soaps of higher fatty acids and compositions containing such fatty materials as essential ingredients, e. g., cookies, cakes, crackers, breakfast cereals, etc., as well a food emulsions such as mayonnaise, may all'be suitably stabilized 'in accordance with this invention. Furthermore, substances such as sulfonated oils and other sulfonated fatty compounds, amides, monoand diglycerides and other fatty substances which tend to become rancid upon exposure to air, may be treated by this invention. Other materials subject to oxidative changes which may be protected wi'th the products of this invention include cosmetics such as face creams, hand lotions, shaving creams, etc.; gasoline, mineral oil, lubricating oils, rubber, etc.

The amount of the extract added to the fatty material to be stabilized may vary considerably, depending upon the activity of the extract and the degree of instability of the fatty material. I have found that oils or fats containing anywhere from about 0.1% to about 20%, preferably from about 0.5% to about of my antioxidant extracts show striking improvements in their stability.

My antioxidants are particularly adapted for the stabilization of fat-soluble vitamin-containing oils or concentrates as well as vitamin-containing fractions recoverable from such products by vacuum distillation, solvent extraction or other processes. This is extremely fortunate for antioxidants capable of tabilizin such products have not as yet been made available on a wide scale. My antioxidants may be added to such materials in any suitable amount without imparting undesirable color, odor, taste or toxicity thereto. Furthermore, the incorporation of'my antioxidants heated to elevated temperatures without substantiaily affecting the activity of the'antioxidants. Moreover, the heating of vitamin-containing oils stabilized by the addition of my extracts does not substantially reduce the vitamin activity of the oils. As a matter of .fact, it was found that by adding the antioxidant extracts of the present invention to substances of a fatty nature havin undesirable tastes and odors and subsequently heating the mixtures to elevated temperatures, e. g., to C., the undesirable tastes and odors of the substances were substantially minimized.

A further advantage of the fractions which are extracted from crude vegetable. oil is that they have valuable emulsifying properties. For example, when a vitamin concentrate is mixed with the ethanol extract of one of the crude vegetable oils, the resulting solution can be readily dispersed in aqueous media to give stable dispersions and, because of the natural antioxidants contained in the extract, the vitamin potency in the alcohol solution is very stable. In dispersing vitamin concentrates in aqueous media for human consumption, it is preferred to use an ethanol solution of an antioxidant fraction and a vitamin concentrate. In some cases it may be desirable to extract the antioxidant fraction from the natural antioxidant-containing fatty material with some solvent other than ethanol. When this is done it is preferable to remove the solvent from the antioxidant fraction and then redissolve the fraction in ethanol before using the fraction to help disperse a vitamin concentrate in an aqueous medium.

A modification or the process hereinabove described which I have found to be particularly successful involves extracting a mixture of a fish liver oil and a vegetable oil containin natural antioxidants with one of the above solvents. As pointed out above, the extraction of a fish liver oil effects a concentration of the vitamins con tained therein in the solvent. Furthermore, the antioxidants of the vegetable oil are also concentrated in the extract so that a highly potent, extremely stable extract is recovered. A similar extraction of a mixture of a vegetable oil and a fat-soluble vitamin concentrate yields an extremely stable extract constituted chiefly of the concentrate and the natural antioxidants and emulsifying agents of the vegetable oil. Furthermore, the vitamin concentrate which is recovered,

particularly when the original concentrate was,

composed of the unsaponifiable fraction of a fish liver oil, is much improved in color, taste and odor over the original concentrate and also generally has a considerably higher potency than the original concentrate.

While the present invention is primarily concerned with the stabilization of oxidizable organic substances of a fatty nature, other oxidizable organic substances such as nonfatty substances containing vitamin C, pyrethrum, essential oils and other materials known to the art may be sta-' bilized by treatment with my novel extracts.

The following examples are illustrative of the method of producing the extracts of this invention; amounts are given in parts by weight:

' EXAMPLE I 200 parts of freshly prepared unrefined wheat germ oil were mixed with 800 parts of 100% methanol and the mixture warmed to about 50 C. in the presence of N2 gas and then thoroughly agitated for 10 minutes. After allowing the mixtujre to cool to room'temperature, the clear su-.

pernatant solvent layer was decanted and the residual oil layer treated twice more exactly as before with fresh batches of methanol. The combined methanol extracts were'then freed of solvent at a low temperature under reduced pressure and in the presence of N2 gas. The resulting extract had an iodine value of l13'as compared to 124 for the original oil and exhibited very strong antioxidant properties.

EXAMPLE II 500 parts of virgin soybean oil were thoroughly agitated with 2000 parts of 100% methanol while maintaing in an atmosphere of N2 gas. The mix- The extract fraction had an iodine value of 116.

as compared to 123 for the crude oil and possessed very strong antioxidant properties.

. The residual oil layer after being freed of solvent was substantially free of break constituents.

EXAMPLE III 200 parts of crude corn oil were treated with 95% aqueous ethanol essentially as in Example I; The extract fraction, exhibited strong antioxidant properties. The iodine value was 109 as compared to 121 for the original oil.

EXAMPLE IV the extracts of this invention. These tests were conducted by maintaining the samples at a constant temperature of 34.5 C. in the presence of air for the indicated number of days and mease uring the percentage of the vitamin A destroyed.

Table Percent vitamin A destroyed Sample 6 days 14 days 20 days Crude shark liver oil v 6. 3 l8. 1 30. 6 Refined shark liver oil 26. 64. 0 Refined shark liver oil containing wheat germ oil extract prepared as in Example I 2.4 12. 8 8 Refined shark liver oil containing 5% wheat germ oil extract prev pared as in Example II 3. 5 13.7 24.0 Refined shark liver oil containing 5% soybean oil extract prepared 7 as in Example III. 3.9 12. 3 20.3

Refined shark liver oil containing I 5% corn oil extract prepared as in Example IV 2.8 12.1 24.3

The above table clearly demonstrates the superiority of vitamin-containing oils stabilized by the addition of my novel antioxidants. It will be noted that the stabilized refined oils of this invention are even more stable than crude shark liver oil so that it is evident that-this invention permits the production-of vitamin oils having no undesirable color, odor or taste and which are neverthelessexceedingly stable to oxidizing influences. v

From the above description it will be evident that this invention provides a new and highly useful method for the recovery ofnaturally'occurring antioxidants from fatty materials with which they are associated. This invention provides a process which is highly economical and which furnishes completely oil-soluble antioxidants. Furthermore, since the present process does notinvolve subjecting the fatty material being treated to saponification or. any other chemical change, the residual material is particularly valuable for a wide variety of purposes after the removal of the antioxidants therefrom.

'Further, th s invention provides a highly useful process for the stabilization of fat-soluble vitamin-containing oils and thus satisfies the demand of the industry for such products. The

present process accomplishes the separation of antioxidants from materials which were thought to contain only a relatively small quantity of these antioxidants, thereby enhancing the value of the fatty materials by permittingathe production vof other valuable by-products therefrom. Because of these factors, it will be evident that this invention will be extremely useful to all those engaged in the production and stabilization of fatty materials. The word crude as used in association with the expressions fatty material and vegetable oil in the appended claims connotes the character and condition of these materials, i. e., that they are in their virgin and unrefined state.

This application is a division of application Serial No. 431,700, filed on February 20, 1942.

Since certain changes in carrying out the above process and certain modifications in the compositions which embody the invention may be madewithout 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. v

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

l. A process for obtaining antioxidants from fatty materials with which they are associated, which comprises contacting a crude fatty material containing'natural antioxidants with a solvent selected from the group consisting of methanol and ethanol, separating a solution containing a. highly active antioxidant extract from the remainder of the fatty material and recovering the antioxidant extract from the solvent solution thereof, said antioxidant extract having an iodine value lower than that of the original fatty material.

2. A process for obtaining antioxidants from vegetable oils with which they are associated,

which comprises contacting a crude vegetable oil which comprises contacting a crude fatty material containing natural antioxidants at a temperature substantially above room temperature with a solvent selected from the group of methanol and ethanol, separating a solution containing a highly active antioxidant extract from the remainder oi the fatty material and recovering the antioxidant extract from the solvent solution thereof, said antioxidant extract having an iodine value lower than that oi the original fatty material. 4

4. A process for obtaining antioxidants from vegetable oils with which they are which comprises contacting a crude v oil containing natural antioxidants at a temperature substantially above room temperature with a solvent selected from the group consisting of methanol and ethanol, separating a solution can a highly active antioxidant extract from the remainder or the vegetable oil and recovering the antioxidant extract from the solvent solution thereof, said antioxidant extract having an iodine value lower than that of the original vegetable o 5. A process for obtaining antioxidants from vegetable oils with which they are ted, which comprises contacting a crude vegetable oil containing natural antioxidants with methanol, the ratio of methanol to oil being than one, and separating the methanol containing a highly active antioxidant utract item the remainder of the oil. said extract having an iodine value lower than that of the original oil.

6. A process for obtaining antioxidants from vegetable oils with which they are associated, which comprises contacting a crude vegetable oil containing natural antioxidants with ethanol, the ratio of ethanol to oil being greater than one, and separating the ethanol solution containing a highly active antioxidant extract from the remainder of the oil, said extract having an iodine value lower than that of the original oil.

7. A process for obtaining antioxidants irom vegetable oils with which they are associated, which comprises contacting a crude vegetable oil containing natural antioxidants with methanol, separating the methanol solution containing a highly active antioxidant extract and recovering the antioxidant extract from the methanol solution thereof, said extract having an iodine value lower than that of the original oil.

8. A process for obtaining antioxidants from vegetable oils with which they are associated. which comprises contacting a crude vegetable oil containing natural antioxidants with ethanol, separating the ethanol solution containing a highly active antioxidant extract and recovering the antioxidant extract from the ethanol solution thereof, said extract having an iodine value lower than that of the original oil.

LORAN O. BUXTON.