US2614937A - Plastic shortenings and process of producing same - Google Patents

Description

Patented Oct. 21, 1952 PLASTIC SHORTENINGS AND PROCESS OF PRODUCING SAME Fredric J. Baur, Wyoming, and Willy Lange, Cincinnati, Ohio, assignors to The Procter & Gamble Company, Cincinnati, Ohio, a corporation of Ohio This invention relates to improved plastic shortenings and to a process for making them. Plastic shortenings are conventionally produced by appropriate thermal and mechanical treatment of a mixture of low-melting oil commonly called basestock and of high-melting fat commonly called hardstock. The basestock is commonly unsaturated in character and predominantly liquid at ordinary temperatures, although it may and frequently does contain a proportion of saturated compounds. Vegetable seed oils, such for example as cottonseed oil and soybean oil, either unhydrogenated or partially hydrogenated, are especially suitable for such basestocks. The hardstock is commonly saturated in character and solid at ordinary temperatures, although it may and frequently does contain a proportion of unsaturated compounds.

Extensively hydrogenated oils are examples of such hardstocks. Even in the case of lard, a small percentage of extensively hydrogenated fat is frequently added in order to obtain preferred consistency at high temperature.

In producing plastic shortenings, the softening action of the liquid basestock and the stiffening action of the solid hardstock are balanced so as to obtain the desired plasticity. If, within the range of temperatures ordinarily encountered in handling shortenings, the basestock is truly liquid even at the lower temperatures and the hardstock remains solid even at the higher ternperatures, a change in temperature within this range will not greatly affect plasticity of the shortening and it is said to have a wide plastic or working range. Such ideal shortenings are seldom encountered. In actual shortenings, hardenings, hardness normally increases as temperature decreases, while on the other hand the material may become mushy at high temperature before complete melting takes place. Both such behaviors are undesirable.

Shortenings composed of mixtures of essentially saturated hardstock and of unhydrogenated vegetable oils may have a desirable degree of plasticity over a range of temperature, but yet contain readily oxidizable, highly unsaturated constituents and hence be subject to rancidity and deterioration on aging. To remedy this defect, the basestock may be partially hydro:- genated. As a result, some saturated fats. may

inadvertently be formed, having a stiffening action on the mixture. In general, if the proportion of hardstock is too great, the shortening will be objectionably hard at lower temperatures, and will be plastic over only a limited temperature range. Keeping quality suffers, however, if the iodine value of the basestock is too high, and particularly if appreciable proportions of combined fatty acids having two or more double bonds are present.

No Drawing. Application May 28, 1949, Serial No. 96,144

20 Claims. (01; 99-118) It is an object of our invention to provide a plastic shortening having an improved working or plastic range of temperature. Another object is to provide such a shortening which will have improved keeping quality on storage. Another object is to provide a shortening of improved resistance to the efi'ects of heat. Another object is to reduce the degree of hydrogenation required in order to produce satisfactory basestocks for such shortenings. Other objects will become apparent in the description which follows.

We have found that these objects can be accomplished by appropriately introducing acetyl groups into the molecular structure of the basestock of the shortening, in conjunction with other steps to be described more fully hereinafter. Mere mixtures of triacetin and conventional basestocks have serious disadvantages, such for example as an excessive tendency to smoke when used in frying. Substantially no triacetin should be present in the final product. In addition to the introduction of acetyl groups, rearrangement of the original high molecular acyl groups, of the basestock also takes place in some cases.

Introducing acetyl groups lowers the melting point, congeal point and cloud point of the basestock, while rearranging high molecular acyl groups, if they be saturated, may under some conditions constitute the production of hardstock in situ in the basestock.

Products prepared by our process have the general qualities of conventional shortenings, but they exhibit better texture stability, improved creaming properties in cake making tests, less gum and foam formation in frying, equal or even improved digestibility and other advantages. Notably, they have as unusually wide range of working temperatures. Furthermore, our process provides shortenings of desirable plasticity from basestocks of lower iodine value than would other wise be possible, and as a result these shortenings are less susceptible to rancidity and other oxidative changes during storage or at elevated temperatures.

Acetyl groups may be introduced and other acyl groups may be rearranged by mixingtriacetin with high molecular edible fat triglycerides, usually but not necessarily containing both'satu- I rated and unsaturated acyl groups, and inti-v mately contacting this mixture in known manner with a rearrangement catalyst until substantial rearrangement of acyl groups in the triglyceride molecules has taken place. Rearrangement is then discontinued, either by removing or by inactivating the catalyst, unreacted triacetin (and in some cases, as will be poined out hereinafter, other low-boiling material) is removed from the system in order to raise the smoke point which would otherwise be objectionably low, and to this substantially triacetin-free, acetyl-containing basestock, hardstock may or may not be added. depending upon the character of the basestock and other considerations to be discussed hereinafter. The mixture is then plasticized in conventional manner.

The following examples, in which all parts are by weight, illustrate ways in which we practice our invention, but it is to be understood that the examples are illustrative only and that the invention is not limited by the details thereof but only by the terms of the appended claims.

Example 1.R-efined cottonseed oil was hydro genated to an iodine value of 74.3, dried under reduced pressure at 120-l50 C. with nitrogen agitation and subjected to a preliminary random rearrangement of the fatty acid radicals (that is, rearrangement in accordance with the laws of chance) by treating it for 1.5 hours at 120 F. with 0.3% sodium methonide catalyst. The catalyst was then inactivated by acidifying with glacial acetic acid and the rearranged oil was water-washed until neutral and steam-distilled for 1.5 hours at 200 C. under about 2 mm. of mercury pressure. (This preliminary rearrangement is unnecessary; rearrangement with triacetin leads to essentially the same results whether or not such preliminary rearrangement has taken place.) Five parts of the rearranged oil were then mixed with one part of triacetin (i. e. about 2 mols of oil to 1.6 mols of triacetin) and the acyl groups were again rearranged in the same manner as above. The catalyst was inactivated as above and the oil was water-washed and then subjected to steam-distillation for 1 hour at 180 C. under about 2 mm. mercury pressure. A large part of the unreacted triacetin was removed in the Water washings. all of the remaining triacetin was removed by the steam distillation, which latter step not sufficiently drastic to remove substantial amounts of other acetyl-containing triglycerides. Table 1 shows changes efiected in the oil by these rearrangement treatments. Calculations based on saponification value indicate that, on a molar basis, 37.4% of the acyl radicals of the substantially triacetin-free product were acetyl radicals.

This substantially triacetin-free basestocl: was next plasticized with 11% of melted hardstock (i. e. 89% basestock+11% hardstoek) consisting of cottonseed oil which had been hydrogenated to an iodine value of about 7, adjusting the temperature of the mixture to 120 F., chilling on steel rolls cooled internally with running water at 50-55 F., and then pumping into a picker box jacketed with cooling water at 70 F. The temperature and pressure of the plastic mass at the pressure release valve of the picker box were about 80 to 84 F. and l#/sq. in. All of the resulting plastic shortening was then tempered for two days at about 80 or 99 F. and individual samples for one day each at the particular tem- Substantially perature at which each was to be given a penetration test in order to determine hardness and plastic range. The purpose of the tempering was to bring the mass more nearly into equilibrium so that there should be little further change in consistency with time. Table 2 gives typical penetration results, the method used being that of the A. S. T. M. Test D217-4'7T (A. S. T. M. Standards, 1947 supplement, part III-A, page 139). For comparison, results are also given for plastic shortenin s prepared in a generally similar manner from (a) the hydrogenated oil before rearrangement, in the absence of triacetin, plasticized with 6% of the hardstock, and (b) the hydrogenated oil after the preliminary rearrangement, in the absence of triacetin, plasticized with 5% of the hardstock. In general we find that shortenings which have usable plasticity give penetration values by this method ranging from about 150 to about 275 units.

1 These values represent the depth, in 1/10 min, to which the penetrometer cone sinks in the plastic fat.

2 I. e. 1 part triacetin to 5 parts of oil.

From the above table it is seen that the change in consistency with change in temperature was much less in the case of the shortening prepared by rearrangement with triacetin in accordance with our invention. The texture of the shortening was smooth and the texture-stability on aging was good. Gum and foam formation were less and performance in cake baking was better than in the acetin-free not-rearranged preparation.

Example 2.-Refined cottonseed oil was hydrogenated to an iodine value of 51 and was then treated as in Example 1 (except that rearrangement was at F.) in order to give a plasticized shortening, using 1 part of triacetin to 2 parts of oil (i. e. about 2 mols of triacetin to 1 mol of oil) in the rearrangement step and only 9.5% hardstock in the plasticizing step. Constants of the material before adding hardstock and plasticizing were as follows:

Calculations based on saponification value indicate that, on a molar basis, 46.3% of the acyl radicals of the substantially triacetin-free product were acetyl radicals.

The penetration values of the plasticized shortening, after a tempering treatment such as was described in Example 1, were as follows, again giving for comparison values for shortenings prepared in generally similar manner from (a) the hydrogenated oil before rearrangement, in

the absence of triacetin, and (o) the hydrogenated oil after the preliminary rearrangement, in the absence of triacetin, both of which basestocks were so hard that no jhardstock was added The acetin-shortening of Example 2 would have better oxidative stability (as indicated by lower iodine'a'nd thiocyanogen values) than that i of Example 1, but the texture is poorer and the plastic or working range is less, 1. e;,-the shorteningof Example 2 is harder at low temperatures andis softer at high temperatures than that of Example 1. However, the consistency of the shortening is such that it can be used in a normal manner, which is not possible with the hard shortenings prepared from the same hydrogenated basestock which was not rearranged with tr-iacetin in accord'ancewith our invention. In fact, the plastic range is slightly better than that of a normal shortening.

Examples 1 and 2 also illustrate the fact that for workable consistency, larger proportions of triacetin shouldbe used the harder the basestock of the shortening.

Example .3.--Refined cottonseed oil was hydrogenated to an iodine value of 76.7 and then rearranged by mixing with one fifth of its own weight of triacetin and 0.3% sodium methoxide catalyst and holding at 130 F. for 1.5 hours. The catalyst was inactivated with glacial acetic acid and the oil was water-washed until neutral. It was then 'freed from unreacted triacetin by steam distillation at reduced pressure. The saponification value (266) of this rearranged oil indicates that, on a molar basis, 35.7% of the acyl radicals of the substantially triace'tin-free product were acetyl radicals.

Plasticizing was carried out as in Example 1, except that there was used 15% of ahar-dstock consisting of lard hydrogenated to about5 iodine value, this amount being required in orderto give the desired consistency. The resulting shorteningwas tempered for two days at 80 F. and was then subjected to penetration tests, with results as follows:

Table 5 I Temperature? F.) or Test 50 so 70 so 90 Penetration Values: Rcarran'ged with20%triacetin 21.5 209 24s 1231 260 tral and subjected to steam distillation at 200 C. for 1.5 hours at 2 mm. of mercury pressure.

Five parts of this oil were then mixed with one part of triacetin and the acyl groups were again rearranged under the same rearrangement conditions. Rearrangement was discontinued by eliminating the catalyst with glacial acetic acid, the sample was water-washed until neutral, and unreacted triacetin and other low-boiling constituents were removed bysteam distillation for 1 hour at 180 C. under about, 2 mm. of mercury pressure. Table 6 shows changes in the oil caused by these rearrangement treatments, the preliminary random rearrangement in the absence of triacetin being an unnecessary step in our process.

Calculations based on saponification value in dicate that, on a molar basis, 40.7% of the acyl radicals of the substantially tri-acetin-free product were acety'l radicals.

This substantially triaeetin-free basestock was next plasticized with 13% 'of melted cottonseed oil hydrogenated to about 7 iodine value, the conditions being the samea's those described in Example 1. After 2 days tempering at F., the consistency of the shortening was tested by the .penetrometer method. Table '7 gives the results, as well as :results on shortenings similarly prepared from (a) the hydrogenated oil before rearrangement, in the absence of triacetin, plasticized with 1.5% of the hardsto'ck, and (b) the hyrogenated oil after the preliminary rearrangement, in the absence of triacetinQplasticized with 5% of the hardsto'ck.

This shortening, rearranged with triacetin, had desirable plastic properties over a wide range of temperature.

Example 5.Refined and bleached soybean oil was hydrogenatedto 61.8 iodine value and was then treated as in Example 4, using 50% triacetin-(i. e. 1 part-of triacetin to 2 parts of oil) inthe rearrangement and 12.5% hardstock in the plasticizing. The saponification value (311.2) of the rearranged oil before adding hardstock indicated that 50.2% (on a molar basis) of the acyl radicals of the substantially triaceti'nefree product were acetyl radicals. Table 8 gives the results of penetration tests upon the finished shortening. A wide working range is indicated, such as would not be possible with soybean oil of this iodine value when converted into a shortening by conventional methods.

Examples 1-5 illustrative ways in which hardstock can be plasticized'with an acetyl-containing basestock of low melting point to yield shortenings of good keeping quality, the desirable consistency of which is only slightly aiiected by wide changes in temperature.

As anothermodification of our process, we may form hardstock in situ from and in the same oil that is used as the basestock, thus avoiding the difiiculty and expense of separately obtaining hardstock. This formation in situ may be brought about, for example, in the manner de-- scribed in U. S. Patents 2, i%2,531 and 2,442,532, by rearranging triacetin and an edible fat triglyceride mixture constituted of combined high molecular fatty acids whose molecular structures differ in respects aifecting solubility of .triglycerides thereof in the triglyceride system. Such rearrangement comprises, in brief, inti- Inately contacting the mixture of triacetin and said edible fat triglyceride mixture with a low temperature rearrangement catalyst at a temperature at which at least a portion of the system is liquid and below 160 F., and then establishing the temperature of the system within a range of temperature of which the lower limit is the lowest temperature at which a portion of the triacetin-fat mixture is liquid and the upper limit is the highest temperature at which higher melting triglycerides can crystallize in the liquid portion of the mixture as they are formed by rearrangement.

Rearrangement in this mixture is eliected by lowering the temperature progressively within such range while progressive crystallization of higher melting triglycerides, as they are formed, takes place and until a substantial increase in the proportion thereof has occurred. Thereafter, the reaction is discontinued by inactivating the catalyst, and unreacted triacetin is removed. The temperature may from the beginning of the rearrangement be sufiiciently low to permit crystallization, as they are formed, of solid triglycerides of low solubility. Alternatively, the temperature may at the beginning be too high for such crystallization but may subsequently be lowered to permit such crystallization to take place.

The mixture of solid triglycerides which form and crystallize during rearrangement (and which are largely high melting, high molecular, saturated and acetyl-free) and of liquid triglycerides, (which predominantly contain both unsaturated high molecular acyl groups and acetyl groups in their molecular structure) may then be plasticized with or without the addition of other hardstock, depending upon the nature of the oil and of the thermal treatment to which it is subjected during rearrangement. Molecular rearrangement of this kind we shall call directed rearrangement because it is subject to control by varying the temperature, to distinguish it from the random type hereinbefore described wherein the composition of the resulting product is controlled by the laws of chance and depends upon therelative proportions of the constituents present. The following example shows how directed rearrangement may be adapted to the process of our invention.

Example 6.Refined and bleached cottonseed oil, hydrogenated to 76.7 I. V., was mixed with one-fifth of its own weight of triacetin and with 0.3% sodium methoxide catalyst at 120 F. for 1.5 hours to effect random rearrangement thereof. The mixture was then'continuously agitated in a closed vessel while the temperature was dropped stepwise as follows: 3 days at F. during which initial precipitation of solid began, 2 days at 70 ER, 2 days at 60 F., 3 days at 50 F. and 2 days at 40 F. At the end of this cycle, the rearrangement reaction in the semi-solid fat was checked by adding glacial acetic acid to inactivate the catalyst, and the mixture was water-washed until neutral and purified by steam distillation at 160-180 C. for 1 hour at 2 to 3 mm. pressure. Saponification value (266) of the rearranged oil indicates that 35.7% (on a molar basis) of the acyl radicals of the substantially triacetin-free product were acetyl radicals. The solid fats which crystallized out were essentially acetyl-free, saturated, and high molecular.

The substantially triacetin-free, acetyl-containing rearranged oil, containing substantially acetyl-free saturated solid triglycerides, was heated to F., chilled on rotating steel rolls having a temperature of 53 F., and transferred to and mechanically worked in a picker box maintained at 65 F., pressure at the release valve being 100#/sq. in. The plasticized fat was then tempered for l days at 80 C. and subjected to penetration testing as shown in Table 9. The data of this table are not comparable with penetration data by the A. S. T. M. method previously presented, since a modified technique was here used. The results are, however, indicative of a wide range of temperatures (30 F. or more) within which the consistency of the product does not change excessively.

The products of Examples 1 to 6, all of which melt below F., have smooth texture and good digestibility and are suitable for use in making cakes and for other customary uses of shortemngs.

A variation of the process illustrated in Example 6 is first to subject the basestock to directed rearrangement in the absence of triacetin, operating at a sufficiently low temperature to cause solid triglycerides of high melting point and low solubility to precipitate from the liquid portion of the triglyceride system. Without permitting the temperature to rise sufficiently to remelt or redissolve the crystallized solids, we next add triacetin and continue the rearrangement within the temperature limits previously recited. In this manner acetyl groups are introduced into the still liquid portions of the basestock, without affecting the solid portions. Catalyst is inactivated and unreacted triacetin is removed as before.

Another modification which is sometimes useful is to grain the basestock before rearranging it with triacetin. For example, an edible triglyceride fat, constituted of combined fatty acids which in their free state differ in meltin point, may be grained by chilling to a temperature within a range the lower limit of which is the lowest temperature at which a portion thereof is liquid and the upper limit of which is the highest temperature at which higher melting triglycerides .acetyl groups.

thereof can crystallize in the liquid portion thereof. The system is held within this temperature range while a substantial amount of crystallization of solid fat occurs. The partially crystallized fat is then mixed with triacetin and a low temperature rearrangement catalyst and the rearrangement. is continued within this temperature range until substantial rearrangement of acyl example by filtration. The liquid or oleine fraction is then used, either directly as the basestock or as the oil to be subjected to rearrangement with triacetin. oleine fraction can be carried out and regulated so as to eliminate highly unsaturated acyl groups such as those of linoleic or linolenic acid, while leaving oleic acyls substantially unaffected, and thus susceptibility to rancidity may be. decreased.

Limited hydrogenation of the Partial hydrogenation of the original oil or fat is also commonly practiced. If this hydrogenation is extensive, it may so harden the oil as to make it useful as hardstock. If the hydro.- genation is of moderate extent it improves the stability of the oil as a basestock. Hydrogenation is permissible before rearranging, or after rearranging but before removing excess triacetin, or after both rearranging and removing triacetin, or after adding hardstock.

Our process makes available as basestocks'not only oils which have been hydrogenated more extensively and to a harder consistency than is the case in conventional shortenings, but also unhydrogenated oils and fats which are normally too hard for use as basestocks unless mixed with softer stocks. Thus fats such as tallow, palm oil, Chinese vegetable tailow, shea butter, cottonseed stearin (obtained by Winterizing cottonseed oil), hydrogenated cottonseed oil stearin and the like, the fatty acids of which have titres of about 40 to about 54, may be utilized as basestocks after being softened by suitable introduction of Beef tallow or palm oil, for example, when rearranged by our process (preferably With about per cent to 50 per cent of their own weight of triacetin) may be plasticized with conventional hardstocks.

It will be seen that the range of triglycerides which are suitable for shortening manufacture is widely extended by our process and in general includes both naturally occurring edible fat triglycerides and those prepared synthetically ,from high molecular fatty acids, by which We mean fatty acids containing about 12 to about 22 carbon atoms. Especially satisfactory shortenings are made by our process from edible fats of from about 45 to about 80 iodine value, derived from such high molecular fatty acids, which fats, after rearranging with triacetin and removing unreacted triacetin by our process, normally have iodine values of about to about '70.

Penetration data of Tables 2 and 4 to 9 illustrate the fact that from oils within these iodine value limits we are able by our process to produce shortenings of workable plasticity and of such wide plastic range thatpenetration values by the A. S. T. M. method increase by less than 50 per 10 cent of the value determined at 50 F. when the temperature of the shortening is raised from 50 F. to F. To the best of our knowledge such a desirable plastic range as this is unprecedented in'shortenings prepared from basestocks below 80 iodine value; heretofore, basestocks of much range, and such shortenings accordingly have poor oxidative stability u The penetration data of these tables also illustrate the fact that from fats ofexceptionallylow iodine value. and therefore of exceptionally good oxidative stability, we are able by our process to. produce shortenings of workable plasticity at room temperature. Thus from our triacetin-free acetyl-contalning 'basestocks of iodine valueabout 4.0 to about 55 We can prepare shortenings which are highly resistant to rancidity and which have at room temperature (60 to F.) plasticity such that penetration values by the A. S. method are above 150. To the best of our know ledge, it has not been possible priortoour'invention to make shortenings of such high penetra tion values as this from basestocks 0t such low iodine value as this. i

Our basestock oils are commonly refined and bleached prior to treatment with triacetin, ,although these steps may be introducedflat later points in the process. For example, alkali refining is often practiced advantageously after inactivating the catalyst, the excess acid used in this step being neutralized in refining. Similarly,

.deodorization of the rearranged oil'and' removal of unreacted triacetin may take place as one and the same step. However, the basestocks-should be dried before the catalyst is added. g

A number of catalysts are known to the art which may be used to introduce acetyl groups into, or torearrange other acyl groups, in the basestocks. Among them are alkali metal soaps or other alkaline salts which are effective at ele vated temperatures and especially in the presence of promoters such as glycerol or other compounds capable of supplying alcoholic hydroxyl groups. To obtain a high degree of reaction in a Short Period of time, without subjecting the oil to the dangers inherent in high temperature treatment, we find especially satisfactory the lowtemperature rearrangement catalysts which operate efficiently at temperatures below using these in the substantial absence of .free alcoholic hydroxyl groups. Examples of catalysts of this kind are the alkali metal alkoxides and particularly sodium alkoxides of monohydric a1- cohols containing less than 5 carbon atoms, as for example sodium methoxide or sodium ethoxide. Finely divided sodium or other alkali metal, conveniently suspended in Xylene .1. other inert liquid medium, may also be used as a catalyst. The amount of catalyst required commonly ranges between about 0.05 per cent and 0.5 per cent, based on the weight of the fat-triacetin mixture. Larger amounts may be used but are usually unnecessary. The drier the fat, the less catalyst is required. percent catalyst is ample. It is added, with stirring, to the dried fat or to the dry acetin or to the mixture of the two at a temperature high enough to cause the mixture to be substantially liquid, but not above 120 C. lest the activity of the catalyst be destroyed.

Under these conditions, random rearrangement rarely requires longer than an hour, after which time the mixture is completely liquid. In the case In most cases, about 0.3

ii of directed rearrangement, longer periods are commonly allowed for crystallization to take place, for example one or more days at each successively lower temperature step.

,other low-boilingconstituents which would adversely affect quality. Temperature, pressure and time ,are' usually so regulated as to avoid decon position or distillation of substantial amounts of triglycerides of higher boiling point than triacetin, e. g. diacetyl triglycerides, monoacetyl Following rearrangement, the catalyst is either removed, as

triglycerides or triglycerides containin no acetyl groups, which triglycerides increase in boiling point in the order named, although in some cases more drastic distillation may be utilized, as will be more fully pointed out hereinafter. tionmay be aided by introducing a slow stream of inert gas. It is our common practice to steam distill under about 243 mm. mercury up to about 180C.

The hardstoclrs which are used in practicing seed and corn oils and the like are Well suited for such use when hydrogenated to sufficiently low ,iodine value, below 10 for example. The stearine fraction of grained oils, particularly if hydrogenated, may also in some cases be used for the purpose. The relative proportions of hardstocl: and basestock in the shortenings of our invention may vary widely as is the case with conventional shortenings, although the hardstock is always present in minor proportion (usually less than one-fifth by weight of the total) in accordance with the requirements for stifiening, while the basestock is always present in major proportion.

When rearrangement with triacetin has occurred, a complex mixture results, the pro-portions of the various constituents depending upon the proportions of triacetin and high molecular fat used upon the conditions of the rearrangement. Thus the rearranged mixture, prior to removing triacetin, will comprise triacetin, high molecular triglycerides, monoacyl diacetins and diacyl monoacetins, and each of these latter groups will be'subject to variation depending on the particular glyceryl carbon atoms to which the various acyl groups are attached. W e prefer that at least an average of one of the high molecular' acyl groups of the original triglyceride should be replaced by acetyl, and for this purpose, at least one mole of triacetin should be add- I ed, prior to rearrangement, to two moles of high molecular fat. The objects of our invention may be attained to a greater or lesser extent even when some molecules of the fat contain no acetyl groups, and this is particularly true when directed rearrangement occurs.

Distilla- 12 that a small percentage of solid fat crystals may sointerlock as to give rigidity, opacity and apparent solidity to a fat, even though liquid fat enmeshed by the crystals may be predominant in amount.

It will be understood that when chilling and plasticizing the substantially triacetin-free mixture take place, the major constituent is the predominantly liquid basestoclr oil into the molecular structure of which one or more acetyl groups have been introduced, and that as minor constituents there are other triglycerides, comprising high molecular, acetyl-free molecules unchanged during the rearrangement and those changed by rearrangement and any additional normally solid hardstock which may be introduced after the rearrangement completed. In addition, water may be present, as in mar garines, and also small amounts of high molecu lar monoglycerides or diglycerides which are frequently used in commercial shortenings as improving agents. Other improving agents including minor amounts of free fatty acids, soaps, lecithin, and emulsifying agents or various types may also be used.

The novel shortening basestoclis which we have described may be prepared in a variety of ways. One of these ways involves interesterification of random molecular rearrangement of esters, in which process there is interchange of acyl groups between acetic esters and esters of high molecular fatty acids. Molecular rearrangement of triacetin and conventional i'ats has been described hereinbefore. It is obvious that instead of using triacetin for rearrangement with fats, other non-glyceride acetic esters may be used if de sired, such for example as methyl or ethyl acetate. Conversely, instead of triglycerides of high molecular fatty acids, other non-glyceride esters of these fatty acids, such for example as the methyl or ethyl esters, may be interesterified with triacetin. In using esters (whether of acetic acid or of high molecular fatty acids) of alcohols other than glycerin, those esters should ordinarily be selected which have lower boiling points than diacetyl triglycerides of high molecular fatty acids, in order that any excess of these non-glyceride esters may readily be removed from the reaction product. For the same reason, any non-glyceride acetic acid esters are ordinarily subject to the further limitation that they should be only those of alcohols which, when reesterified with high molecular fatty acids, form therewith esters more volatile than the high molecular diacetyl triglycerides. It will thus be seen that in general, except as pointed out hereinafter, the rearrangement reaction mixture should be free or" non-glyceride esters except those which are more volatile than diacetyl tri-glycerides which contain a high molecular acyl group.

Interesterification processeswhereby high molecular monoor diacetyl triglycerides are formed are also feasible with incomplete or partial glycerol esters, i. e. with mono or diglycerides, which may be generically called superglycerinated fats. For example, stearyl diacetin can be formed by catalytically rearranging acyl groups in a mixture of triacetin and monostearin.

Acetylation of superglycerinated fats is also feasible by ways other than molecular rearrang ment. Ehus superglycerinated fat, either i elted or dissolved in a solvent, may be heated with acetic anhydride in the presence of sodium acetate or with acetic acid in the presence of a desiccating agent and a catalyst, or with acetyl is effective at low temperatures.

chloride in the presenceof sodium carbonate,

pyridine or other tertiary amine as an acid acceptor. i

a Allo'f these processes whereby triglycerides are formed which contain both high molecular acyl groups and acetyl groups in their molecular structure are for convenience referred to hereinand in the appended claims as acetylation, and the -superglycerinated fats to which reference has been made may be readily prepared in various ways. A convenient method is to rearrange molecularly a mixture of glycerin and a high molecular fatty acid ester, commonly an edible fat, in random manner under the influence of a rearrangement catalyst, preferably one which Conditions of such rearrangement may 'be substantially those described in Example 1, the relative proportions of glycerin and fat being so selected as to give the desired proportions of the desired glycerides, commonly a major proportion of monoand diglycerides, in the finished product. byFeuge andBailey, in Oil and Soap, vol, 23, page 359, for an exposition of the relationship between initial and finalproportions of constituents in the random rearrangement of glycerinfat mixtures.

The rearranged mixture, commonly comprising'rearranged triglycerides, free glycerin, and a major proportion. of monoand diglycerides, maybe acetylated in conventional manner, for example with acetyl chloride. The acetylated 'mixture will thus comprise rearranged high mo-- lecular triglycerides, triacetin (from glycerin), a

major proportion of diacetyl and monoacetyl triglycerides (from monoand diglycerides respectively) and in addition, free acetic acid (from excess acetylating agent) will also commonly be present. For use in shortenings, impurities such as acetic acid and triacetin which have a lower boiling point than the diacetyl triglycerides, are

then removed as previously described by distillation, and the thus purified material may be mixed with hardstock and plasticized in conventional manner. i

I Before acetylating the rearranged glycerin-fat -mixture of the preceding paragraph it may be freed of uncombined glycerin by washing with ZOper cent sodium sulfate solution, in which case the step of subsequently removing triacetin is not required and a brief distillation sumces to remove low-boiling impurities.

Instead of reacting glycerin with fat or other high molecular fatty acid esters, the glycerin may be esterified in known manner with less than its equivalent weight of the mixed fatty acids themselves, thereby forming a mixture which in addition to free glycerin and high molecular triglycerides contains a major proportion of mixed monoand diglycerides. This reaction product may also be acetylated, freed from low-boiling impurities and used as a shortening basestock.

Throughout this description, reference has been made to distillation as a method of freeing See article the reaction product of triacetin or other lowboiling impurities. It is to becunderstood, however, that means other than distillation, such for example as crystallization or fractional solvent separation, can be used for such purification. Our invention therefore contemplates use of such other means also, and is not it!) be restricted'to purifications by distillation.

Furthermore, our invention has been described as though it were limited to removal from the acetylation reaction mixture of those materials which have a lower boiling point than diacetyl triglycerides. However, our invention is in fact not so limited. For example, if distillation is to be used to remove low-boiling material from the acetylationreaction mixture, we may if we desire raise the temperature and/or lower the pressure or otherwise make more drastic the distillation so that substantially all material is removed which boils at a lower temperature than monoacetyl triglycerides of high molecular fatty acids. Thus diacetyl triglycerides as well as triacetin may be removed, and by so doing a basestock is produced which is improved with respect to smoking, 1. e. the shortening therefrom may be heated to a higher temperature before smoking becomes objectionable. If diacetyl triglycerides are thus removed, it is in general necessary in order to attain a given softness to use larger proportions of the acetyl-containing triglycerides than is the case when diacetyl triglycerides are allowed to remain.

Incase diacetyl triglycerides are to be removed, less narrow limitations need be imposed on the esters from which the acetylated fat is to be obtained. It is then required only thatin the case of nonglyceride esters, those should be selected which have a lower boiling point range than do monoacetyl triglycerides of the high molecular fatty acids in question, and likewise that any nonglyceride acetic acid esters used as acetylating agents be those of alcohols which, when reesterified with the high molecular fatty acids in question, form therewith esters more volatile than themonoacetyl triglycerides of such fatty acids.

It will thus be seen that our process of producing acetylated basestocks maybe broadly generalized thus: We prepare a mixture comprising essentially triglycerides which contain in their molecular structure both acetyl groups and acyl groups of high molecular fatty acids. Wedo this by acetylating mono-, dior triglycerides of high molecular fatty acids or mixtures of such glycerides, or if the acetylation be by molecular rearrangement, instead of rearranging triacetin with high molecular triglycerides as is customary, we may if we desire either (a) rearrange triacetin with low-boiling, non-glycerol esters of high molecular fatty acids or (b) rearrange a low-boiling, non-glyceride ester of acetic acid with high molecular triglycerides, the nonglyceride esters in either case being so selected that any non-glyceride esters present in the rearrangement reaction mixture are more volatile than diacetyl triglycerides (or in a narrower aspect of the invention, monoacetyl triglycerides) of high molecular'fatty acids. Following acetylation, the reaction mixtureis substantially freed from materials which are more volatile than diacetyl triglycerides (or in a narrower aspect of the invention, monoacetyl triglycerides) of high molecular fatty acids, such for example as'excess acetylating agent or low-boiling products derived therefrom. The purified product, which is commonly a mixture of monoacetyl and diacetyl triglycerides and triglycerides containing no acetyl groups, is then suitable for use as a shortening basestock.

In the foregoing discussion of the various ways of making the products claimed herein the word may is used to indicate that one has a choice between two or more entirely practical alternatives; it denotes ability, not mere possibility. All of the foregoing methods result in satisfactory preparation of the novel products of the invention.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

l. A process. of manufacturingplastic shortenings containing an amount of hardstock consist ing of triglycerides of high molecular weight saturated fatty acids materially in excess of the amount of such triglycerides obtainable by random rearrangement of all the glycerides of said shortenings, which comprises preparing a mixture comprising essentiallytriglycerides which contain in their molecular structure both acetyl groups and acyl groups of highmolecular fat y acids, said mixture being free of non-glyceride esters whose volatility is not greater than that of diacetyl triglycerides, removing from said mixture materials more volatile than diacetyl triglycerides of said fatty acids, the combined fatty acids of the resultant mixture being at least /5 acetic on a molar basis, chilling substantially triacetin-free triglycerides comprising as a major component the thus purified product, and comprising a minor amount of said hardstock as a firming agent and forming, same into a plastic mass.

2. A process for producing plastic shortenings containing an amount of hardstock consisting of triglycerides of high molecular weight saturated fatty acids materially in excess of the amount of such triglycerides obtainable by random rearrangement of all the glycerides of said shortenings, which comprises (a) acetlyating a mixture of glycerides comprising at least one member of the group consisting of mono-, diand triglycerides of high molecular fatty acids, thereby obtaining a mixture of triglycerides free of non-glyceride esters whose volatility is not greater than that of diacetyl triglycerides of said fatty acids, a substantial proportion of the triglycerides of which mixture have in their molecular structure at least one acetyl group and at least one acyl group of a high molecular fatty acid; (b) freeing the reaction product substantially of material more volatile than diacetyl triglycerides of said fatty acids; the combined fatty acids of the resultant product being at least acetic on a molar basis, and (c) chilling substantially triacetin-free triglycerides comprising as a major component the thus purified product, and comprising a minor amount of said hardstock as a firming agent and forming same into a plastic mass.

3. A process for producing plastic shortenings containing an amount of hardstock consisting of triglycerides of high molecular weight saturated fatty acids materially in excess of the amount of such triglycerides obtainable by random rearrangement of all the glycerides of said shortenings, which comprises: (l) acetylating a'mixture comprising glycerol and superglycerinated fat of high molecular fatty acids, thereby to form a mixture comprising riacetin and triglycerides which contain in their molecular structure both acetyl groups and acyl groups of high molecular fatty acids, said mixture being free of non-glyceride escore whose volatility is not greater than that of diacetyl triglycerides of said fatty acids, (2) removing triacetin from the acetylated mixture, the combined fatty acids of the resultant mixture being at least /5 acetic on a molar basis, and (3) chilling substantially triacetin-free triglyceries containing as a major component the resulting mixture, and a minor amount of said hardstock as a firming agent, and forming same into a plastic mass.

l. A process for preparing plastic shortenings containing an amount of hardstock consisting of triglycerides of high molecular weight saturated fatty acids materially in excess of the amount of such triglycerides obtainable by random rearrangement of all the glycerides of said shortenings, which comprises molecularly rearranging acyl radicals in a liquid mixture of an acetic acid ester and triglycerides of high molecular fatty acids, said mixture being free of non-glyceride esters whose volatility is not greater than that of diacetyl triglycerides of said fatty acids, removing from the reaction product materials more volatile than diacetyl triglycerides of said fatty acids, the combined fatty acids of the resultant product being at least /5 acetic on a molar basis, and chilling substantially triacetin-free triglycerides comprising as a major component the thus purified product, and comprising a minor amount of said hardstock as a firming agent and forming same into a plastic mass.

5. A process for preparing plastic shortenings containing an amount of hardstock consisting of triglycerides of high molecular weight saturated fatty acids materially in excess of the amount of such triglycerides obtainable by random rearrangement of all the glycerides of said shortenings, which comprises molecularly rearranging acyl radicals in a liquid mixture of triacetin and esters of high molecular fatty acids, said mixture being free of non-glyceride esters whose volatility is not greater than that of diacetyl triglycerides of said fatty acids, removing from the reaction product materials more volatile than diacetyl triglycerides of said fatty acids, the combined fatty acids of the resultant product being at least /5 acetic on a molar basis, and chilling substantially triacetin-free triglycerides comprising as a major component this purified product, and comprising a minor amount of said hardstock as a firming agent and forming same into a plastic mass.

6. A process for producing plastic shortenings containing an amount of hardstock consisting of triglycerides of high molecular weight saturated fatty acids materially in excess of the amount of such triglycerides obtainable by' random rearrangement of all the glycerides of said shortenings, which comprises molecularly rearranging acyl radicals in a mixture of triacetin and high molecular edible fat triglycerides under the influence of a rearrangement catalyst, discontinuing the rearrangement reaction, removing unreacted triacetin from the rearranged mixture, the combined fatty acids of the resultant mixture being at least acetic on a molar basis, chilling substantially triacetin-free triglycerides comprising 'as a major component the resulting rearranged mixture, and comprising a minor amount of said hardstock as a firming agent and forming same into a plastic mass.

7. The process of claim 2 wherein the high molecular edible fat contains both saturated and unsaturated triglycerides and has an iodine Value between 45 and 80.

assesses cam process:- Qr rp QdHCih r pl siic sh n eni containing" an amount'ofchardstoc ns-isting of ri lycer des of hi h-mo ecularw i taturated fattyqacids 1 materially {in excess of; theamountof such triglycerides obtainable by random rearrangement, of all the glycerides of said shortening whichrcomprisesthevstepsof (l molecularly rearranging; acylraclicals; in a mixture of triacetin: and=v high molecular edible fat, themolar ratio; r of triacetin fat being at; least 1 :2, t and the said; rearranging being effected by intimately'contacting sai-d mixture, in; the substantial absence of compounds containing; alcoholic; hydroxyl groups, with a low -ternperature-- rearrangement catalyst at a temperature, below -120 C., at which the: -S2Lld1 mixture; is at least; partially-liquid and continues so to be duringthe rearrangement 'reaction; (2;);inactiyating the catalyst; 39 removingsubstantially all lunreacted triacetin from the earranged mixture; and: 4) chil in ubsta e hall-st riac tin eew ism enid s-c mpr s n a maior ccmp n. heesul in pur fied m x r t nd l qomnr shne a: m no amouht f s i ar stock: r i immaraseht nd i or i a m int ne plastic mass; the rearrangement of step (1) be,- hst qh nue i Unt -5 5 5 lon 7 i 'h, a mhl h s-i h as lr tdicals 1 1?" h a e inr r rearrangemprcduct are acetyl radicals;

9;: A process-Jorp roducing plastic shortening containing-an amount of hardstock consisting-of tri !y eritiesofv high molecular weight saturated fatty acidslmaterially in excess 1 of" the. amountof ch ly rides o ai by an om earan ment t he-smashes fi hhr enr ing, which comprises molecularlyt rearranging acyl radicals a ,mixture of triacetin ands triglycerides ofhigh molecular fatty acids byintimately contacting said; mixture in liquid, state at; a temperature below 125 C. with a catalyst which is an alkali metal; alkoxide Off a monohydrie alcohol containingiless than Bearbon atoms, acidifying the reaction mixture to inactivate the catalyst; removing; unreacted triacetimfrom the rearranged; mixture distillation under reduced pressure at, a temperature, insufficiently high to distill 1substantialrq iantitiesof other triglycerides o n e y t -11av e mb ned. fatty a ids. oftheresultant mixturebeing at least; acetic on, a molar basis, chillingsubstantially triacetinef reetriglycerides comprising :a major c h nt e sultinar a a e imi u ei and comprising; a minor amount; of said hardstock as: a. firming agent, and-forming same into a plase emasa The process, of; claim; 2; wherein high meltingsubstantial y at rated s b atgl cerides are: added to1 the substantially triacetin-f reeg re;- ar ahg dt mixtu t pr to: h l d? fo min same intota, plastic, mass 1 1. A- process! for produeingplastic :shortenings e ami amoun hardstock consistin -0 g yc id s hi olecu r wei ht saturated mnsem ntl ahes la nd nti a -suh a ial f t ia t tes e lx in ex essyoi he amount of i a h h elyc id s q tai abl br random rearrangementtqfrall the; glycerides of said shortenings, which comprispfit intimately contacting triaoetin, high molecular edible fat triglycerides constituted combined high molecular fatty acids, whose moleeularstructures" diffier. in respects affecting solubility of triglycerides thereof in the triglyceride systemand a low temperature rearrangement catalyst, at a temperature at which at least a portion of the triacetin fat mix r i liquidand'below .1 0 R; stabli mns the temperature of-the mixture within a range -of l' tris rcerih s v at h h mq .erid at; eqhsti ut i i mel n p0 law st emneratu e .t hi

inc ease n; the; prqner i n e as O c rred; di sonti hhig the ar a m aci ena e: mov n -J n a ted,, i t hi item; he; re r n es; thaw .hih ztfa ty ci s i e esu t: n-h ixtura e at ast. /5, ac ti n. a mo ar b s s;- hilli s b tant a r riac t ne ee trislwe ides 0mph. gas am ior c m q t he r anged; mixt re nd; c mp i in a m ner a d hardstochasafi m nsagentra e mama-1n a c mass 1 cor-ital cam-his aitmcids mat r m es Qi eamount-hf sushi i l erides; qbtaih hle b e rand m; ha assm nt o [al he yeer ci s 0f said, h hss, which ompr s m te r ont-h nna an edib e at r ly ridemi ture: n tuted of combin d! hi h, mol cul r, a t -a s eimastructu es if er in esne s ie t hs soluhili xei trielycerides heneofi n the ly r e: system, a ow t mp at re-a m l c l r e r an m nt; at yst em a emne aiu ta b lew i608 and with n a, -es f" mp a ure f which; the lower; limit, is 1 the lowest; temperature at whmh a-pprt' ,neofvthe triglyceride mixtur eis i liithancl the-1 upper; imitz s h w g s am: phrat ra atewhicht e sh n me nstr sl r de m ecules ant ys alli e m he quidort on; of he m x ure asthem ra Qrm y ea ran e: merit; mainta hihs e-te pe aturea ft them xr tumv within s id an e wh h osre si e hys: tallizat-iq l Qfv higher; melting; triglycerides iormed in; the, rearrangement takes-place and; until, a sub tant l ncre se in" the pro n; t ereo hasoccur e t, adciina ae h t he-re r an d m a uneand on nuinghe ie r hsem nt wi hr he sa sia temp rature nge nti a ubstan: tial, exchange of 1 et l groups nd of high moiecula acyl groups has taken; place 1. 5 8 1 37 cules of the mixture: discontinuingthe, r ran emeh t ea tion; emo ing uhr a e u iiiacet n, f m he rear angeim' t r he; m-

binect atty: aa x r -v bein i l-line subixture', an a n ofsaid r s has afirming; a ent and or -ins; ame mtoaplastic 1. 15. 53:

m rplfls i hm'teninss containing; amount rdstock qnsisting'of her: wei ht saturated 655591 he amount of l andom l des: Ofr said" shortenngz; an; edible triglycs zihfi r high molecuei-e free state; differ pfir turewithin a ternlowes 1 of which is; the

fatty acigls mater lly in tnslxee esl htai e sme t- 11.. Qt alt th g1 whi h QQI 'Hl AQSr h ular'iat a ac ds which neratute ahae. t

is liquid and the upper limit OFWhj-Chl is: the

o ,s pnos si a r s al a ion hag; er melting;triglycerides iormed in, the rearc ,not i n; of- 'saidiat highest temperature at which higher melting triglycerides of said fat can crystallize in the liquid portion of said fat; holding the said fat within this temperature range while a substantial amount of crystallization of solid fat occurs; intimately mixing the partially crystallized fat with triacetin and with a low temperature rearrangement catalyst at a temperature within said temperature range; holding the mixture within the said temperature range until substantialmolecular rearrangement of acyl groups has taken place; inactivating the catalyst; removing substantially all unreacted triacetin from the rearranged mixture, the combined fatty acids of the resultant mixture being at least acetic on a molar basis; chilling substantially triacetinfree triglycerides comprising as their major component the resulting mixture, and comprising a minor amount of said hardstock as a firming agent and forming same into a plastic mass.

14. A process for producing plastic shortenings containing an amount of hardstock consisting of triglycerides of high molecular Weight saturated fattyacids materially in excess of the amount of such triglycerides obtainable by random rearrangement of all the glycerides of said shortenings, which comprises chilling edible fat trigylcerides, constituted of combined fatty acids which in their free state differ in melting point, to a temperature within a temperature range the lower limit of which is the lowest temperature at which a portion of said fat is liquid and the upper limit of which is the highest temperature at which higher melting triglycerides of said fat can crystallize in the liquid portion of said fat; 13$

holding the said fat within this temperature range until a substantial amount of solid fat has crystallized; removing the crystallized solid fat from the system; intimately mixing the residual liquid fat with triacetin and a low temperature rearrangement catalyst at a temperature at which the system is liquid and below 120 C.; maintaining the mixture at such temperature until substantial molecular rearrangement of acyl groups has taken place; inactivatingthe catalyst; removing substantially all unreacted triacetin from the rearranged mixture, the combined fatty acids of the resultant mixture being at least /5 acetic on a molar basis; adding high melting substantially saturated edible fat to the substantially triacetin-free rearranged mixture;

chilling the product and forming same into a plastic mass.

15. A plastic shortening which melts below 125 the fatty components of which consist of a minor proportion of triglycerides of high molecular saturated fatty acids materially in excess of the amount of such triglycerides which would result from random rearrangement of all the glycerides of said shortening, and a major proportion of a mixture of low melting triglycerides in which at least per cent of the combined fatty acids, on a molar basis, are acetic and in which there is substantially no triacetin.

16. A plastic shortening which melts below 125 F., the fatty components of which comprise a minor proportion of high molecular saturated triglycerides containing substantially no acetyl groups, materially in excess of the amount of such triglycerides which would result from random rearrangementof all the glycerides of said shortening, and a major proportion of triglycerides having at least one acetyl group per mole-.

cule, the said shortening being substantially free from triacetin.

17. A plastic shortening the fatty matter of which consists of: (a) a major amou t f a mixture of glycerides which is predominantly liquid. at room temperature and has an iodine value of about 40 to 70, a major proportion of which glycerides are triglycerides characterized by a molecular structure in which at least one acetyl group is present, and (b) a minor amount of normally solid substantially saturated g1ycerides of high molecular fatty acids, materially in excess of the amount of such glycerides which would result from random rearrangement of all the glycerides of said shortening; said shortening being substantially triacetin-free and having a plastic range such that penetration values determined by the A. S. T. M. method increase by less than 50 per cent when the temperature of the shortening is increased from 50 F. to F.

18. A plastic shortening the fatty matter of which consists of (a) a major amount of a mixture of glycerides which is predominantly liquid at room temperature and has an iodine value of about 40 to 55, a major proportion of which glycerides are triglycerides characterized by a molecular structure in which at least one acetyl group is present, and (b) a minor amount of normally solid substantially saturated glycerides of high molecular fatty acids, materially in excess of the amount 'of such glycerides which would result from random rearrangement of all the glycerides of said shortening; said shortening being substantially triac'etin-free and being of such plasticity that its penetration value as determined at room temperature by the A. S. T. M. method exceeds 150.

19. A substantially triacetin-free plastic shortening basestock composed essentially of mixed triglycerides of combined acetic acid and combined high molecular fatty acids of titre between 40 and 54, the molar ratio of acetyl groups to high molecular acyl groups in said basestock being from about 1 :4 to about 2:1.

20. A process of manufacturing plastic shortenings containing an amount of hardstock c0nsisting of triglycerides of high molecular weight saturated fatty acids materially in excess of'such triglycerides which would result from random rearrangement of all the glycerides of said shortenings, which comprises preparing a mixture comprising essentially triglycerides which contain in their molecular structure both acetyl groups and acyl groups of high molecular fatty acids, said mixture being free of non-glyceride esters whose volatility is not greater than that of monoacetyl triglycerides of said fatty acids, removing from said mixture materials more volatile than monoacetyl triglycerides of said fatty acids, the combined fatty acids of the resultant mixture being at least acetic on a molar basis, chilling substantially triacetin-free triglycerides comprising as a major component the thus purified product, and comprising a minor amount of said hardstock as a firming agent, and forming same into a plastic mass.

FREDERIC J. BAUR. WILLY LANGE.

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

UNITED STATES PATENTS Name Date 2,154,452 Jenness Apr. 18,-1939 2,309,949 Gooding Feb. 2, 1943 2,442,531 Eckey June 1, 1948

Claims (1)

1. A PROCESS OF MANUFACTURING PLASTIC SHORTENINGS CONTAINING AN AMOUNT OF HARDSTOCK CONSISTING OF TRIGLYCERIDES OF HIGH MOLECULAR WEIGHT SATURATED FATTY ACIDS MATERIALLY IN EXCESS OF THE AMOUNT OF SUCH TRIGYLCERIDES OBTAINABLE BY RANDOM REARRANGEMENT OF ALL THE GLYCERIDES OF SAID SHORTENINGS, WHICH COMPRISES PREPARING A MIXTURE COMPRISING ESSENTIALLY TRIGLYCERIDES WHICH CONTAIN IN THEIR MOLECULAR STRUCTURE BOTH ACETYL GROUPS AND ACYL GROUPS OF HIGH MOLECULAR FATTY ACIDS, SAID MIXTURE BEING FREE OF NON-GLYCERIDE ESTERS WHOSE VOLATILITY IS NOT GREATER THAN THAT OF DIACETYL TRIGYLCERIDES, REMOVING FROM SAID MIXTURE MATERIALS MORE VOLATILE THAN DIACETYL TRIGLYCERIDES OF SAID FATTY ACIDS, THE COMBINED FATTY ACIDS OF THE RESULTANT MIXTURE BEING AT LEAST 1/5 ACETIC ON A MOLAR BASIS, CHILLING SUBSTANTIALLY TRIACETIN-FREE TRIGLYCERIDES COMPRISING AS A MAJOR COMPONENET THE THUS PURIFIED PRODUCT, AND COMPRISING A MINOR AMOUNT OF SAID HARDSTOCK AS A FIRMING AGENT AND FORMING SAME INTO A PLASTIC MASS.