US2410102A - Process for hydrobleaching glyceride oils - Google Patents

Description

Patented Oct. 29, 1946 PROCESS FOR HYDROBLEACHING GLYCERIDE OILS William J. Paterson, Newton Highlands, Mass,

assignor to Lever Brothers Company, Cambridge, Mass., a corporation of Maine No Drawing. Application March 31, 1941, Serial No. 386,086

21 Claims.

The present invention relates to the preparation of improved products from glyceride oils which are susceptible to an improvement in stability against rancidity and color or odor, or both. More particularly the invention relates to a novel treatment of glyceride oils with hydrogen in the presence of a catalyst to provide an improved product with respect to color, odor, plasticity and stability.

The crude oils which are made available to the manufacturer of glyceride oil products and which have been prepared in accordance with the usual practice are generally dark in color and contain a substantial amount of undesirable impurities, such as free fatty acids, gums, mucilaginous material, and the like. Moreover, these oils are normally odoriferous and otherwise objectionable, particularly when the object is to use them as edible substances for example, for

culinary purposes.

Heretoiore, the crude oil generally has been subjected to a series of refining, decolorizing, hydrogenating and deodorizing operations to remove objectionable constituents from the oil and to improve its stability, color, odor and flavor. The particular procedure followed and the severity of the treatment depends to a large extent upon the'type and initial purity of the crude oil as well'as the desired characteristics of the final product.

In general, the initial refining of the oil is accomplished by subjecting the oil to a treatment with caustic alkali, which neutralizes and precipitates the free fatty acids as soaps. At the same time, a substantial proportion of the gums, mucilaginous materials-and coloring mat ter is coagulated and removed along with the fatty acid soaps.

T provide an oil of particularly good quality, it is not uncommon to subject the oil to a rerefining operation in which the refined oil is again subjected to the action of caustic alkali, generally in a more dilute solution. A further removal of foots, although smaller in amount, is thus effected which is highly beneficial in im proving the quality of the finished product with respect to color and freefatty'acid content. An inherent disadvantage of the re-refining operation is a substantial further loss of neutral oil by saponification and entrainment, and therefore the use of the re-refining operation is undesirable from an economical standpoint.

Further, in accordance with the art of preparing glyceride'oil products, the refined oil is generally improved in color by a subsequent bleaching treatment With a usual bleaching agent of the carbon or earth type. The bleaching agents, it is believed, effect a decolorizing action by absorbing coloring matter from the oil. Thebleaching agents and the absorbed coloring matter are then removed from the oil by filtration. It has been observed that bleaching agents also absorb a substantial amount of oil, and that factor, in addition to the relatively high cost of,

satisfactory bleaching agents, and the difficulty and expense of filtration, adds greatly to the expense involved in manufacturing glyceride oil products.

When a hardened product for use in shortening, for example, is desired, the refined and decolorized oil is hydrogenated by means of hydrogen gas in the presence of a metallic catalyst such as nickel and generally at elevated temperatures. Incidental to the hardening of the oil, a further improvement in color generally takes place.

The refined and bleached oil, either hydrogenated or unhardened, may then be deodorized by subjecting the oil to a treatment with steam under reduced pressure conditions.

It is an object of the present invention to avoid the multiplicity of processing steps heretofore regarded as essential in the manufacture of good grade products from glyceride oils. In particular, it is possible by the practice of this invention to dispense with the uneconomical steps of rerefining With alkali anddecolorizing by the use of bleaching earths and the like as discussed above. The novel treatment of glyceride oils with hydrogen in accordance with the present invention may be substituted in whole or in part for re-refining, bleaching, and hydrogenation in accordance .with the prior art methods, and when used in conjunction with ordinary refining and subsequent deodorization, for example, with steam, provides glyceride oils products of unexcelled color, odor, plasticity and stability, as discussed more fully hereinafter.

A particular object of the present invention is to provide a method whereby unbleached oils may be bleached and hardened simultaneously, if desired, to at least the degree required in the production of good grade glyceride oil products.

The treatment of a prime cottonseed oil for the manufacture of edible oil products by the methods described above may be taken as typical and. involves the problem of color removal. A representative crude cottonseed oil ranges from dark reddish-brown to almost black in color when expressed from the seed. Upon being refined with alkali, ,a representative oil exhibits a color of approximately 5.0 red/35.0 yellow. All color values referred to herein are in Lovibond units and have been measured with a Lovibond tintometer provided with a 5 /4 inch column. A subsequent bleach in accordance with the standard procedure approved by the American Oil Chemists Society using 6% of the official fullers earth and employing a temperature of 120 C. improves the color to approximately 2.0 red/20.0 yellow. Upon hydrogenation to shortening consistency, such an oil usually exhibits acolor of 1.0 red/10.0 yellow A cottonseed oil which has .been re-refined with, alkali in addition to being subjected to the treatmerit outlined above, may sometimes, when choice, oils are used, exhibit after bleaching a color of 1.5 red/15.0 yellow and after hydrogenation a color of 0.7 red/7 .0 yellow. With respect to. edible. cottonseed oil, a color reduction below approximately 0.5 red previously has not been believed to be economically or practically possible by; the prior methods of the industry even when the highest grade raw oil is treated.

Hydrogenated cottonseed oil is utilized principally as. the major ingredient of shortening products In this connection, it is to be observed that most commercial shortenings average about 2.0 red/29.0 yellow and seldom. are below 1.5 red/15.0 yellow, I i

It is known in the art that special methods, such as distillation andheat treatment at high temperature, will effect a high degree of color reduction in oils, but these methods, as a rule, aretoo severe as well as complex and expensive r: ene l us e p c ally n. h v e ara Q edible oilproducts.

Therefore, it is an, object of the present; invenion o provide a me h d f r ec l l ns lycerfavorably affect the odor and flavo products made therewith;

The readily available supply of soybean oil r of the food makes its utilization attractive to the manufacturer, Nevertheless, the use of soybean oil has been, greatly limited, particularly in high grade edible products, inasmuch as it has been impossible to'avoi'd. the undesirable characteristics of soybean oil, particularly with respect to deep frying, unless the oil is hydrogenated to the relatively hightitre of 51 0.. which corresponds to an iodine value of about 50, and consequently I hardened to such an extent that it can be used only in restricted amounts. In general, an iodine value in the range of, 70 to 80 and a penetration of 220' to 25.0 is desired in'a hardened soybean oil when the object isto utilize the'oil in shorten ing. Even with the use of the most effective hydrogenation methods of the prior art, a satisfactory shortening capable of'meeting' the high present-day commercial standards cannot be prepared having morethan about 10 to of hydrogenated'soybean oil. a

A particular object of this. invention is to provide a method of decolorizing glyceride oils such as soybean oil which imparts stability against his oil o asr at r deereethanfhas. e n p b e heretofore without adversely affectingthe desire...- ble characteristics of theoil. with respect to its use, for example, for edible. purpose i i A particular object of. this invention isto provide a method for decolorizing cottonseed oil to. form anedible product which is. characterized by an improved water-white appearance;

Another object of the invention istoeffect an improved decolorization of glyceride. oils in a. manner which permits thecontrol of thehardena ing of the oil whereby an edible oil product of improved color and. odor maybeproduced in aliquid stateor having any desired plasticity characteristics. 7 1 1 Theproblem of odor reversion in edible oils may be. easily appreciated by a reference, for example, to soybean oil. The characteristics of soybean-oil in this connection are discussed in some detail in the Epstein, et a1. Patent-No. 2,140,794,.issued December 20,1938. a

It is well' known' that soybeanoil refined--byprior methods and evenafter the usual hydro genaticn to a lard-like consistency; undergoes a type of spoilagewhich is characterized as reversion'," particularly-when exposed to light and air and temperature conditions,'- such as 385" R, usually encountered when the shorteningis used for deep; frying. The reversion of soybean oil isv characterized by the development of various oiT i flavors and lodorsknown as a bean'yif flavor" or odor and sometimes described as fishy, which subsequently often becomealtered with the production of othenundesi-rable flavors classified" as oleoand grassy.

One of-the-mainobjections to the use, for exarnple; of hydrogenated soybean oil in shortenand odors,

ings isthe reversion 'toa characteristic but undesirable odor of the oil at the elevated temperaturesemployedfordeep frying, *In the commercial practice of; deep' frying, the fat may be maintained atatemperature of about-385 F. for

several days, any loss from; the fat body; being i replaced byadditions of further shortening. The

objectionable odors and flavors which develop are not-only undesirable during frying but also unreversion and good" deep-fry characteristics to the oils. Another object of thi invention'is to provide a methcdof forming asoybean' oil product; stable against reversion under deep-frying; conditions and which is sufficiently plastic to be used in' unlimited proportionsin shortenings. 7

It i well known in the chemistry ofoils and fats that the glycerol esters of fatty acids, which are the principal constituents of glyceride-oils and fats tend to become rancid due to the formaa tion of various aldehydes' and lower fatty acids with possibly ketones which are all very unpleasantly odoriferoussubstances. Before these substances are'formed; however, the fat must go through a preliminary stage'of oxidation (usually atmospheric) withthe formation of. organic peroxide; further oxidation resulting in the rupture, of the fatty acid chains with theformation of low molecular weight products responsible for the off'flavors and rancidity. The process of oxidation and development of rancidity rendersthe oil unsuitable for mostfus'es, particularly Wherethe object is to'use the oil for edible purposes. The tendency of the oil to turn rancid as j the result of oxidation -may' be minimized [by saturating the unsaturated fatty acid-components present in; the oils with hydrogen. The stability of the oil, in general-{increases proportionately with the decrease'iniodine'value of-the oil. It is understood, however that complete saturation 7 characterized bythe formation of a hard, brittle solid-is undesirable; for example, when the object isto-use theoi-l'fored-ible purposes; In general, it is customary to 'hydrogenate the glyceride oil to a degreewhich gives a product of lard-like consistency at room temperatures} Inasmuch as the usual types of glyceridefoils are not; completely saturated at 'thi'sconsistency, theoil will development of rancidity.- a W It is anobject of-the-present-invention to pro,- vid'e a method-of hardeningglyceride oils and fats whereby the oilsexhi'bita greater stability against oxidation. and the development of ranbe susceptible to undesirable oxidation and the .cidity' as-.compared with oils hardened" tothe same iodine value-or consistency in accordance.

with theprior art practice;

The present process which, for convenience,

is designated as hydr'obleaching is not to .be'

with respect to flavor, color, and in the case of oils such as for example, soybean oil, freedpm from reversion, particularly under deep-frying conditions. Hardening of the oil so treated may or may not result, dependent upon the characteristicsdesired'in the final product. The degree of hardening of the oil effected by the practice of the invention may be controlled 'within wide limits by a careful selection of the particular catalyst used and by regulating the-conditions of operation, as set forth more fully hereinafter.

Vegetable oil products of reduced iodine value resulting from the present process may be readily used in the production of all-purpose shortenings and are found to have the desirable plasticity over a relatively wide range of temperatures, as well as color, odor and stability. ing the preferred use in the process of elevated temperatures and of relatively high pressures as compared with the pressures normally used in hydrogenating vegetable oil in thepresence of a nickel catalyst, it has been fOllnd that thereis littletendency to form the hard, brittle products resulting when similar conditions are used with nickel catalyst.

The catalysts which may be employed satisfactorily in accordance with this invention comprise oxides which, for convenience, may be described as the type XY-O in which X is at least one metal selected from the minor sub-groups of groups I and II, and Y is at least one metal se-' lected from the minor sub-groups of groups V and VI, of the periodic classification. O, of course, represents oxygen; that is, the metals are in the form of oxides. The minor sub-groups of groups I, II, V and VI of the periodic classification comprise divisions of the main, groups as shown, for example, in the periodic chart appearing at page 46 of volume I of International. Critical Tables. The minor sub-group of group I comprises copper, silver and gold. The minor sub-group of group II comprises zinc, cadmium and mercury. The minor sub-group of group V comprise vanadium, .colu mbium, tantalum and protoactinium. The minor sub-group of group VI comprises chromium, molybdenum, tungsten and uranium.

It will be apparent that a great number of combinations or mixtures of combinations ofthe above designated metals are possible in accordance with this invention. It is to be expected that the activities of the several species of catalysts will vary over a-wide range and, in general, it is preferred to utilize those metals from the groups designated above which, in general, exhibit the greatest activity under the preferred conditions of effecting the hydrobleaching of the oils. It is to be understood, however, that the scope of this invention is not to be limited to the use of the particular metals so selected.

In general, copper and silver comprise the preferred metals of the group designated by X while chromium, tungsten, vanadium and uranium are preferably selected from the group designated by Y; Typical combinations of the, selected metals, by way of example comprise copper-chromium oxide, silver-chromium oxide, copp er- Notwithstandtungsten-oxide, copper-uranium-oxide and copper-vanadium-oxide.

The proportion of metals indicated by X and Y is not regarded as critical and may be varied over a wide. range depending upon the particular metals selected and the conditions of operationv under. which the same is to be used. In general, a substantially atomic ratio of X and Y is preferred'for effecting desirable resultsin accordance with theinvention.

In general, it is preferred to stabilize thecatalyst. by the presence of an alkaline earth metal oxide, such as barium oxide or calcium oxide, al-- though this is not essential. Substantially an atomic ratio of X and Y and m of a mole of alkaline earth metal has generally been found to 'be preferable, but the proportions may be varied as desired and depending upon the particular metals selected as well as upon the conditions under which the same is to be used.

The exact form of the metals or the oxygen in the catalyst is difiicult to determine, and it is not intended that the invention shall be limited to any particular chemical or physical combination. It is-possible that the catalyst maybe a simple mixtureof the separate oxides of the two metals present in the catalyst, but it is equally possible that the two metalsand the oxygen may be combined .to form a distinct and separate chemical compound. It is intended-that the scope of the invention shall includethe use oftwo or more metals of the type describedin combination with oxygen, regardless of the exact chemical or physical structure of the composition. It is possible that even asto those oxide catalysts which, at the present time, do not appear to have a preferred activity, a modification may be made in their physical form or structure which'may make their use desirable. p

The methods utilized in preparing the oxide catalysts described above will have, in-general, an appreciable effect upon their relative effectiveness and properties. A number ofvariedmethods may be employedyit is possible, for example, to prepare-a catalyst having the desired composition by simply grinding together a mixture of the, selected oxides and subsequently heating the mixtureto an elevated temperature. It is preferred, however, to utilize one of the following methods.

v hods 300 ml. of a solution containing 8'7 g. of

hydrated .copper nitrate (Cu(NO3)2.3I-I2O) and 6.6g. of calcium nitrate (Ca(NO3)2) are added to 240 ml. of a solution (25-30) containing 50.4 g. of ammonium dichrornate and 150 ml. of 28% am monium hydroxide... vThe precipitate 'is'filte'red, dried-at 75-802 pulverized, and decomposed at elevated-temperatures. r

' j MethodBfa '10 grams (T 0- m.) chromium trioxide (CrOs); 24.2 I g. (1- m.) of hydrated copper nitrate (CufNOz) 23H2O) and.2.6 grams m.) barium nitrate j(Ba(NOs)z) are dissolved in cc. water and 20 cc. m.) 28% aqueous ammonia is added with constant stirring. The precipitate is filtered, dried at 100 C. and decomposed at 350 C.

MethodC' v 40 grams m.) chromium nitrate I (Cr(NO3)39H20) I v V 24.2 grams-(T 6 m .)'copper nitrate;

' (Cu(NO3)2.3I-I2O)..

and 2, ms (not m. b ium nae (Barron;

similar conditions, i. e., with. 0.2% catalyst/for thirty minutes at 200 C; and. over 2000 lbs.. per" sq. in. pressure.

Methodtfr prepara' Catalyst 7231 122 I v Red Yellow Method A, Cu-Cr-CIi-O IO-16' O. 1 1. O d- 2 O. 7 7.0. Method B Cu-Or-Ba-O 4. 0.3 3.0 Method 0 d0 21 0:2 2.0

It'will be observed that theactivity of the cat-1 alyst prepared in accordance with the above methods vary relatively both with respectto their color-removing properties and their ability to hydrogenate orlower the iodine value of the oil. The results efiected by Method A, however, are not uniform and are difficult to reproduce. It will be apparent that themethod of preparing the catalyst may be selected on the basis of whether decolorizing'with or without substantial harden ing is desired.

In general, special treatment of the oxide catalyst prepared in accordance with this invention, such as reduction with hydrogen or leaching with acid, will have no appreciable beneficial effects upon the activity of. the catalysts. 1 I

It is difficult to determine why catalysts of substantially the same chemical composition will vary in their relative merits depending upon the method utilized in preparing the same. It'is-believed that the variance may be due to the difference in physical properties, possibly as-the result of the difference in decomposition conditions: In general, a precipitate decomposition which takes place spontaneously at low temperaturesis more difhcult to control and there-forethe results obtained thereby are more difficult to reproduce. Catalysts prepared by spontaneous decomposie tion, moreover, tend to exhibit less activity for hardening purposes.

Olxide catalysts, of the kind disclosed; above, have been used heretofore in the hydrogenation of various organic compounds to. produce alcohols, hydrocarbons, and; similar unsaponifiable matter. In particular, in accordance with. the prior art, the hydrogenation of-glyceride oils using a mixed oxide catalyst would result in the formation of unsaponifiable matter comprising higher ketones, such as. palmitone-and stearone; alcohols, such. as .dis'teanyl carbinol;- hydrocar-i bons, such as pentatriacontane; aswell as corresponding fatty. acids, which are very objection-v able inasmuch. as. they cannot. be removed by. ordinary deodorization. processes. Unsaponifiable matter is, objectionable, for example, in..ed ible food products, because it is not fat. Inaccordance with accepted standards, a good grade shortening will havexlessthansonepercent of unsaponifiable matter. v

Accordingly, in addition. to providing for the hydrobleaching of glyceride .oils. to eifect an improvement in color or stability 'or both, having the advantages and ramifications discussed above, this invention further provides an opera tion during the hydrobleaeh-ing process to; effectively retard the formation. of unsaponifiable matter. By this process, a. decolorized and hardened product suitable after filtering, deodorizing, texturizing and like finishing operations for use. as a shortening is obtainable. 'In addition,

even with oils such as, for example, soybean oil,

a product is obtained which-is stable against reversion. These products have unsaponifiablev components, but only inamounts comparable with that. ordinarily present in good grade com mercial shortenings. In fact, With this process,

1.0%. unsaponifiable components. I V I 1 In general, the desired! hydrobleaching o glyceride oils may be accomplishedin accordance with this invention by disposing an oil, preferably already alkali. refined, in a suitable closed vessel, and preferably under elevated. temperatures and pressures. The .oil is maintained in contact with: a. relatively smallamount of the preferred oxide catalyst of the type described above.

Preferably relatively high pressures are utilized, the hydrogen, being charged at pressures prefer.- ably in the neighborhood of 100 atmospheres. or more. The oil is maintained in a heated condition. and for a sufficient period of time, generally not less than 10 minutes, for the'desired hydrobleaching to go to; completion. After hydrobleaching isco-mpleted, the oil may be treated in the conventional manner, such as filtering, deodorizing, chilling, aerating, texturizing or otherwise finishing. It isdesirable, of course, to minimize its contact withair at least until cooled. The preferred temperatures which may. be used.

in carrying out the inventionwill generally range from 130 C. to 250 C. Below 130 C; the rate off reaction is reducedlso that the eifective decolfall below the. standards required, for example, in

the production of edible oil products. At temperatures above 200 C- there is a tendency toward the formation of unsaponifiable matter such as ketones; alcohols, hydrocarbons, and the'higher acids, which are usually considered undesirable in high grade products as discussed above, although in certain cases this may not be critical. In"gen-' eral, it is desired not toexceed a temperature of 5 250 C. at which point decompositionofglyceride oilsbegins to take'place.

The amount ofcatalyst which is used is preferably approximately 02% based on the weight of the oil, although'this may be varied Within reasonable limits. It has been found that when the amount of catalyst; exceedssubstantially 0.5

there is formed an increasing amount of un'-" In general, the catalyst.

saponifiable material. should Ice-present in an amount of at least"0:1%

inasmuch as when smaller amounts are used the ct desirable results is greatly time requiredto eife increased.

To effect decolor-ization and stabilization to the I greatest extent, it is preferred to carry out-the process under relatively high pressures such as inthe neighborhood 'ofat; least. 1500- lb -per square inch, but this ,isznotregarded asessentialfor desirable results; Forexamplej'pressures as low as atmospheric may be used if desired. In

7 general; a moreeffective decolorization and stabilization is accomplished at higher pressures;

' It is generallydesirable to avoidj'unduly; pro

longing the operation- 'to 'avoid the formation or undesirable by-products] particularly unsaponi fiable material; However, ifa"-subs'tantially uni-form products mayxbemade with less than;

orization and stabilization in general appears to 9 water-white oil is desired-the time of hydrobleachingshould tend toward a maximum preferably with an increase in pressure conditions and amount of catalyst employed. In general, it is not desirable to exceed a hydrobleaching period in the neighborhood of 60 minutes.

The process has been disclosed in the specific examples as a batch operation, as by so doing simple and easily understood standard pressure equipment may be used. However, it will be apparent that the process may be carried out in a continuous manner. For example, the oil may be heated and subjected to hydrogen pressure for a desired period of time in an elongated restricted passageway through which the oil may be passed continuously or semi-continuously with or over a catalyst. The oil may then be continuously filtered if desired and treated in any of the conventional ways.

To illustrate the eifective stabilization against reversion accomplished by the process, reference may be had to the following specific example of an operation applied to dry, refined, unbleached soybean oil.

A high pressure bomb was charged with 270 grams of dry refined (unbleached) soybean oil and .27 gram (.1%) of the Cu-Cr-Ca-O catalyst. Air was displaced from the bomb with hydrogen, and hydrogen introduced at a pressure of 1900 lbs. per square inch. The bomb was agitated and heated to 225 C., at which temperature it was maintained for one hour. The bomb was then cooled, the oil removed and filtered to free it of metallic oxide. The oil was still liquid at ordinary temperature, being only about 10 iodine values more saturated than the original oil. The color, however, was very close to water-white, being less than .1 red/1.0 yellow Lovibond in color in a inch column. The oil was then hydrogenated to 70 iodine value with .10% nickel catalyst at almost atmospheric pressure and 150 C., filtered, treated with a small amount of fullers earth, and deodorized.

The oil was tested and compared with a sample of the same oil which had not received any special treatment except that it had been hydrogenated to the same consistency as the sample treated at high pressure with the oxide catalyst and deodorized. The comparative test consisted in maintaining 50-gram samples of each of the fats at 160 C. and noting any changes. The samples were in 50 mm. x 70 mm. crystallizin dishes placed on the surface of a thermostatically-controlled hot plate. A thin layer of Woods metal was used to make a good thermal contact between the hot plate and dishes. The odor and color of the samples were noted and compared at intervals over a period of two to three hours, the test being intended to simulate the conditions of deep-fat frying in household and bakeshop practice. The untreated sample rapidly acquired the characteristic undesirable odor of hydrogenated soybean oil and darkened rapidly in color, but the treated sample was so greatly improved that only the faintest residual odor of been oil became apparent and the reversion of color was considerably retarded.

The novel results obtained with respect to color are further illustrated in the following table showing the improvement of color of selected representative prime cottonseed oils eifected by treatment in accordance with the prior art and compared with a treatment by hydrobleaching using a Cu-Cr-Ba-O catalyst in accordance with this invention.

Color of oil Treatment Sample 1 Sample 2 Sample 3 R Y R Y R Y Alkali refined 4.8 35 4.7 35 6.6 60 Bleached with 6% earth for 5 minutes at C i. l. 6 16 2.0 20 2.8 28 Hydrogenated to 70 I. V. at C.

Wlth .l% nickel .9 9 1.5 15 2.2 25 Hydrogenated at 200 C. and 2,000

lbs. sq. in. Hz pressure for 30 minutes with .2% copper-chromium- 1 oxide .1 l .1 l .5 5 Iodine values lowered (during hydroblcaching) 10 16 8 It is apparent that the color obtained by treatment with a small amount of oxide catalyst, for example, a Cu-Cr-Ba-O catalyst, in accordance with this invention, represents a decided improvement over that which can be obtained by fullers earth bleaching or hydrogenation with nickel or both.

To illustrate the improved stability against rancidity obtained by hydrobleaching with an oxide catalyst, as compared with hydrogenating in accordance with the prior art utilizing a nickel catalyst, reference may be had to the following tableof results obtained by hardening identical samples of the same cottonseed oil to the same degree of saturation in accordance with the two methods being compared. Hydrobleaching was carried out in accordance with the invention under a pressure of about 2500 lbs. per sq. in. and a temperature of 200 C. utilizing a copperchromium-oxide catalyst. Hydrogenation was effected at the same temperature, i. e., 200 C. and under atmospheric pressure using a selective nickel catalyst prepared in accordance with the method disclosed in the patent to Paterson No. 2,123,342, issued July 12, 1938. The quality tests were carried out under carefully standardized conditions. The measurements comprised maintaining the samples of oil at a temperature of 130 C. (:01" C.) and bubbling clean air throu h the oil at a rate of 10 liters per hour, for a period of 4 hours, and thereafter determining the amount of peroxide by well known methods of analysis. The quality of the sample or its potential stability against oxidation rancidity is expressed in terms of mini-equivalents of oxygen per kilogram of oil formed under these conditions. As has been explained heretofore, among the first products formed in the oxygen process are peroxides, and a determination of the peroxide contents of an oil or fat has been accepted by the art as a particularly suitable and standard means for calibrating or comparing the extent of oxidation or decomposition in an oil or fat.

Percent Quality t 1 t Iodine linolein oven Test 0a a 375 value (2 double bonds) Test Test Days 69. 8 10. 0 16. 7 39 67. 5 8. 2 12. 6 66- 1 7. 1 10. 1 d0 63.3 5.0 5.2 111 Copper-chromium-oxide 70. 9 10. 1 9. 6 76 (lO 67.5 7.1 6.7 63. 6 3. 7 3. 3 180 It will be noted by comparing Test No. 2 utilizing a nickel catalyst with Test No. 6 utilizing a hydrogenated with oxide-catalyst at an elevated I although they Jmaiy' not achieve under 'the same pressure .to the same degree of saturation, i. e., 67.5 iodine value, reacts with oxygen at only about half the rate of the oil hardened in accordance with the prior art. This difference may be explained in part by the more selective hardening accomplished with the oxide catalyst, but it is found-that an oil hydrogenated :in the pres.- ence of nickel catalyst having thesame linolein content (Test No. 3) has an iodine value of 66.1 and .a quality test of 10.1, which is substantially higher than that of the oil hardened. with the oxide catalyst (Test No. 6). e

The above quality tests were confirmed by subjecting Nos. 1, 4, 5, and '7 to a controlled oven test in which 50 gram samples were incubated at 63 C. (:0.5 C.) in 100 ccfbeakers covered with a watch glass. The samples were smelled daily until they became rancid and the quality of the samples is expressed as the number of days during which they remained fresh. Samples 1 and 4 which were hydrogenated to 69.81. V. and 63.3 I. V. respectively in the usual way with nickel had an oven test of 39 'and 111 days, respectively while Samples 5 and '7 which were hydrobleached to 70.9 I.'V. and 63.6 I. V. respectively had an oven test of '76 days and more than 180 days, respectively.

It is not intended that the novel result obtained by this process is to be limited to any theory of operation, but apparently the hydro- -bleaching process either destroys or converts existing pro-oxygens in the oil or forms additional anti-oxygens.

In order that the variations and scope of the invention may be more readily understood, reference may be had to the following table of test results showing the efiect of varying the type and amount of catalyst, pressure, temperature conditions the most .efiective color "reduction and hardening accomplished with a Cu-'Cr Ba-'O"ty.pe :of loxide catalyst. It .has been observedth'at the color, reduction effected by the use of a catalyst containing vanadium -.or tungsten undensome f conditions may not 'be stable, but this may be remedied by treating the oil with causticiimm'ediately after hydrobleaching, whereupon the oil is 'foundto besatisfactory in every respect. t

It will be apparent that in accordance with this invention the process .of decolorizing :and hardening vegetable oils maybe accomplished by the'use of various "techniques,. as desired. For example, the oil may be "simultaneously decolorized and hardened by the use of a preferred oxide catalyst under such conditions of operation that sufficient hardening takes place during hydrobleaching. The oil may be decolcrized, and

in thecase of soybean oil, for-example, stabilized against reversion in one operation and, if 'de sired, may be hardened in a separate operation. If the amount of hardening accomplished by the use of an oxide catalyst is not sufficient for the purposes for which the oil is to be used, it is possible to harden the oil either prior or subsequently to hydrobl'ea'ching, by the use of an'oxide catalyst having more suitable hardening characteristics, or under more effective hardening conditions. I

It is to be understood that the hydrobleaching of oils in accordance with this invention may be carried out by using any of the variations set forth above and all of these variations are intended to be included within the scope of the invention. V g

In the examples given above, it Will be note that the reduction in color and the hardening which takes place increases with an increase in and time. 40 the pressure under which the process is carried Test Amount T e of oi1 1 Pressure Temper- Time Hardening Fma] color Catalyst alkah ure I. V. N ,0. Catalyst refined) lbs. sq. in. o O mm. 1

per cent uwered Red Yellow 0.2 Cottonseed 2,000 200 30 21 0.2 2.0 0.2 do 2,000 200 30 1 0.2 2.0 0.2 '2, 000 200 30 None 1. 4 14. 0 .0. 2 2, 000 200 30 None 1. 5 15. 0 0.2 1 d0 2, 000 200 30 5 0.4 4.0 0. 2 Soybean- 2, 000 200 30 10 0. 1 l. 0 0. 2 1 1do 2, 000 200 30 1. 5 0. 2, 2:0 0. 2 .do 2, 000 200 30 None 0. 5 5.0 1. 0 Cottonseed.- 2. 000 250 30 35 Water-white O. 2 do tm. 200 60 None 1. 'l 11. 0 0.5 do 2,700 200 .60 0.1 1.0

will be observed that the amount of decolorization and hardening which takes place depends to a large extent upon the type of catalyst employed. In general, sufficient hardening, that is to an iodine value of approximately 70 and simultaneous decolorization to a substantially water-white oil may be obtained by the use of 1.0% of CIu-C'r-Ba-O catalyst, for example, under relatively high pressures for approximately thirty minutes. .(Test No. 9.) The use of the process under these conditions, however, may not be desirable because of the formation of unsaponifiable matter in the oil, particularly if it is used for edible purposes. Therefore, it may be desirable in some cases to use a smaller amount of catalyst and a lower temperature, as shown in Test No. l.

The results obtained by substituting silver for copper, or by substituting vanadium, tungsten, or uranium for the chromium are satisfactory,

Maximum Color Iodme Sample No. g f z gi 35 3 value inch Y R 1 Atmos. pressure,

It will be noted that the extent of hardening of the oil (iodine value drop) is almost directly proportional to the pressure utilized. However, in the case of color improvement, although a fair degree of bleaching is obtained at atmospheric pressure, a very marked increase in decolorization is obtained by increasing the pressure to about 500 lbs. per sq. in., and the maximum bleach is obtained by increasing the pressure to about 1500 lbs. per sq. in. A further pressure increase has no appreciable efiect on the degree of decolorization.

In order to obtain both maximum color removal and hardening, it is preferred to accomplish hydrobleaching under a pressure of approximately 100 atmospheres or greater, but it will be observed that under lower and even atmospheric pressures desirable results are obtained.

In order to illustrate the effect of varying the temperature under which the process is carried out, upon the degree of hardening and decolorization obtained, reference may be had to the following table of test results obtained by hydrobleaching identical samples of a representative cottonseed oil having an original iodine value of 106 and a color of 6.4 red/35 yellow: for 30 minutes With .2% of a copper-chromium-oxide catalyst under a pressure of 2250 pounds.

The above chart indicates that satisfactory hydrogenation and decolorization is obtained at temperatures beginning in the range between about 125 and 150 C. and the rate increases as a function of increasing temperature. In general, the lowest temperature for obtaining satisfactory results is believed to be about 130 C.

The preferred temperature under which the process is carried out to obtain maximum hardening and color reduction is approximately 200 0., although other temperatures, for example, in the range of 130-250 C. may be used eiiectively. At lower temperatures the reduction in color and iodine value tends to be less, while at more elevated temperatures, the oil has a tendency to decompose and there is formed an undesirable amount of unsaponifiable material. In general, however, an increase in temperature will cause a proportionately greater color and iodine value reduction.

It has been found desirable to limit the time of operation in some cases to approximately thirty minutes or less subsequent to the heating of the oil to a sufficient temperature for effective decolorization and stabilization. 'Although the reduction in color and iodine value will be a function of the amount of time during which the oil is maintained at elevated temperature, it will be found that the maintenance of the oil at elevated temperatures may act to cause the formation of relatively large amounts of ketones, alcohols and hydrocarbons.

By hydrobleaching soybean oil in accordance with this invention, it is possible to produce a stable product of good color which will not suffer a reversion in odor and flavor. Moreover, this improvement in the characteristics of the soybean oil may be accomplished without an appreciable hardening of the oil or by a simultaneous hardening to any desired plasticity. As a result, the soybean oil product may be used in good grade vegetable shortening in any desired amount up to The eifective improvement in color and stability against rancidity accomplished in accordance with this invention has been demonstrated in the case of cottonseed oil, for example, which now by this invention may be prepared apparently waterwhite as compared to oils of a color of 1.0 or at the best .5 red now available in the industry and with a stability substantially 100% greater than an oil hardened to the same degree in accordance with the standard practice.

Although the invention has been described particularly with reference to cottonseed oil and soybean oil, it is to be understood that this has been done merely for convenience and to assist those skilled in the art to appreciate the novel and desirable results which may be attained. It will be apparent that the invention is applicable to all gylceride oils and fats or mixtures thereof of animal, vegetable or marine origin which are susceptible to an improvement in color or sta bility or both.

Among the oils which have been treated successfully with hydrogen in accordance with this invention are, for example, palm oil, sesame oil, peanut oil, coconut oil and tallow. The following table illustrates the effective reduction in color obtained by treating the above named oils in accordance with my invention with 0.2% copperchromium-oxide catalyst for 30 minutes at 200 C. and about 2500 lbs/sq. in. hydrogen pressure.

It is to be understood that glyceride oils which have been processed in accordance with this invention, in addition to having an improved color and stability against reversion under deep-frying conditions, have all of the qualities requisite for conversion to, and use in, an all-purpose shortening. The glyceride oils which have been hydrobleached in accordance with the invention will be finished in the conventional manner, such as, for example, by filtering, deodorizing, chilling, aerating and texturizing when the same is to be used in edible products such as shortenings. A shortening made from oils treated in accordance with this invention is plastic and workable over a reasonable range of temperatures, and may be readily creamed and when used for baking purposes produces cakes of good volume and texture.

The variations to which this invention is susceptible by one skilled in the art are intended to be included within the scope of the invention.

I claim:

1. A process for hydrobleaching glyceride oils to form edible products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at a temperature of from to 250 C. with hydrogen under a relatively high pressure in the neigh 13. A method of decolorizing cotton seed oil to produce a product having a Lovibond color of .5 red yellow, or lower which comprises treating the oil at an elevated temperature with hydrogen in the presence of a small amount of a catalyst having the general formula X-YO, in which X represents at least one metal selected from the minor sub-groups of groups I and II, and Y represents at least one metal selected from the minor sub-groups of groups V and VI, of the periodic classification.

14. A process for hydrobleaching glyceride oils to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at an elevated temperature with hydrogen in the presence of a small amount of a catalyst having the general formula X-Y-ZO in which X represents at least one metal selected from the minor sub-groups of groups I and II, and Y represents at least one metal selected from the minor subgroups of groups V and VI, of the periodic classification, and Z represents an alkali earth metal.

15. A process for hydrobleaching glycerid oils to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at an elevated temperature with hydrogen in the presence of a small amount of a catalyst having the general formula X-Y-Z--O in which X represents at least one metal selected from the group consisting of copper and silver, and Y represents at least one metal selected from the group consisting of chromium, vanadium, tungsten and uranium, and Z represents an alkali earth metal.

16. A process for hydrobleaching glyceride oils to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at an elevated temperature with hydrogen in the presence of a small amount of a catalyst having the general formula X-Y-ZO in which X represents at least one metal selected from the group consisting of copper and silver, and Y represents at least one metal selected from the group consisting of chromium, vanadium, tungsten and uranium, and Z represents an alkali earth metal, said metals represented by X and Y being present in substantially atomic relationship and said metal represented by Z being present in onetenth molar relationship.

1'7. A process for hydrobleaching glyceride 11 18 to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at a temperature within the range of substantially to 250 C. with hydrogen in the presence of a small amount of a catalyst comprising copper,

chromium and oxygen.

18. A process for hydrobleaching glyceride oils to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at a temperature within the range of substantially 130 to 250 C. with hydrogen in the presence of a small amount of acatalyst comprising silver, chromium and oxygen.

19. A process for hydrobleaching glyceride oils to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at a temperature within the rang of substantially 130 to 250 C, with hydrogen in the presence of a small amount of a catalyst comprising copper, vanadium and oxygen.

20. A method of hydrobleaching glyceride oils to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating the oil at an elevated temperature with hydrogen in the presence of a small amount of a catalyst having the general formula XY-O, in which X represents at least one metal selected from the minor subgroups of groups I and II, and Y represents at least one metal selected from the minor subgroups of groups V and VI, of the periodic classification, and subsequently similarly treating the oil in the presence of a catalyst having the general formula X--YO, in which the metals represented by X and Y comprise at least one other metal from the groups designated.

21. A process for hydrobleaching glyceride oils to form products having a minimum of unsaponifiable components and an improved color and stability comprising treating th oil at an elevated temperature with hydrogen in the presence of a small amount of a catalyst having the general formula X--YO in which X represents at least one metal selected from the minor subgroups of groups I and II, and Y represents at least one metal selected from the minor subgroups of groups V and VI, of the periodic classification,

WILLIAM J. PATERSON.