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`1
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`PROCESS FOR PREPARING A Cu-CM
`SATURATED FATTY ACID ESTERIFIED
`ALKOXYLATED POLYOL
`
`FIELD OF THE [NVENTION
`
`5,466,843
`
`2
`removed from certain foods.
`
`This invention relates to methods whereby C lz—Cz,1 satu-
`rated fatty acid-esterified alkoxylated polyols useful as
`reduced calorie fat substitutes may be conveniently and
`economically prepared. The invention provides a process
`wherein excess unreacted (1,241,, saturated fatty acid may
`be readily recovered from an esterification reaction product.
`
`BACKGROUND OF THE INVENTION
`
`A wide variety of substances have been propoacd for use
`as fat substitutes in food compositions. The chemical struc-
`tures of such substances are selected such that they are more
`resistant to breakdown by the metabolic processes of the
`human digestive system which normally occur upon inges-
`tion of conventional
`triglyceride lipids. Because of their
`increased resistance to digestion and absorption, the number
`of calories per gram available from the fat substitutes is
`considerably reduced as compared to common vegetable
`oils, animal fats, and other lipids. The use of such substances
`thus enables the preparation of reduced calorie food com-
`positions useful in the control of body weight.
`US. Pat. No. 4,861,613 (incorporated herein by reference
`in its entirety) describes one class of particularly useful fat
`substitutes wherein a polyol such as glycerin is alkoxylated
`with an epoxide such as propylene oxide and then esterified
`with any of a number of fatty acids or fatty acid derivatives
`to form an esterificd alkoxylated polyol. These substances
`have the physical and organolcptic properties of conven—
`tional triglyceride lipids, yet are significantly lower in avail-
`able calories than edible oiis owing to their pronounced
`resistance towards absorption and pancreatic lipase enzy-
`matic hydrolysis. The thermal and oxidative stability of the
`csterified alkcxylated polyols renders them especially suit-
`able for use in the preparation of reduced calorie food
`compositions requiring exposure to high temperatures such
`as fried or baked foods.
`
`Unfortunately. as a consequence of their hydrolytic sta-
`bility and low digestibility, hilly liquid versions of esterified
`alkoxylated polyols described in US. Pat. No. 4,861,613
`may tend to cause certain undesirable gastrointestinal side
`effects when consumed at high levels in the dict. That is,
`since such esterified aJJtOxylated polyols are not readily
`broken down into simpler substances upon ingestion, they
`largely retain their oily, fat-like character and pass through
`the digestive tract in substantially unaltered form. Non-
`digestible fat substitutes in general often function as laxa—
`tives in much the same manner as mineral oil. Problems with
`diarrhea,
`leakage of the fat substitute through the anal
`sphincter, separation of the fat substitute as an oil from the
`excreted fecal matter, and shortened bowel transition times
`resulting in gastrointestinal discomfort can occur as a result
`of the non-digestibility of the fat substitutes. Other fat
`substitutes which are similarly resistant towards digestion
`are also known to produce such gastrointestinal side effects.
`Examples include sucrose polycstcr which is esterified with
`up to 8 fatty acid groups; see US. Pat. Nos. 3,954,976,
`4,005,195, 4,005,196, and 5,006,360. Obviously, such prob-
`lems will greatly limit the maximum usage level of these
`substances which can be tolerated in various food compo-
`sitions.
`thereby constraining the amount of conventional
`triglyceride and the number of calories which can be
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`Page 2 of 6
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`One solution to this problem is provided in European
`Patent Publication No. 571,219. This European application
`describes a fatty acid-esterified propoxylated glycerin corn-
`positicn useful as a reduced calorie fat substitute resistant to
`gastrointestinal side eifects having an average number of
`oxypropylene units per equivalent of glycerin of from 3 to
`20, a fatty acid acyl group content such that at least 40 mole
`percent of the fatty acid acyl groups in the composition are
`derived from a Cm—Cz4 saturated linear fatty acid, and a
`solid fat index at 27° C. as measured by dilatometry of at
`least 30. The utilization of such a composition in combina—
`tion with a conventional frilly digestible fatty acid triglyc—
`eride fat or oil in a food composition normally containing a
`fatty component is also described. The European application
`suggests that these fatty acid-esterified prepoxylated glyc-
`erin compositions may be obtained by first propoxylanng
`glycerin with the desired number of equivalents of propy-
`lene oxide and then esterifying with a fatty acid or fatty acid
`equivalent such as a fatty acid ester, or fatty acid halide, or
`a fatty acid anhydride.
`The use of fatty acid esters in such an esterification step
`is described in US. Pat. No. 5,175,323 {incorporated herein
`by reference in its entirety}. The fatty acid esters employed
`in this process are C1—C4 alkyl esters of saturated or unsat-
`urated Cw—Cu fatty acids. The esterification reaction is
`readily driven to completion by removing the C1—C4 ali-
`phatic alcohol generated during the transesterification reac-
`tion by distillation or similar means. Although this approach
`works well on a laboratory scale and afiords a high yield of
`estcrified alkoxylated polyol with minimal lay-products or
`color formation, it suffers from the practical disadvantage
`that the required C1 to C4 alkyl esters are relatively expen-
`sive as compared to the corresponding free fatty acids. In
`addition, great care must be taken to ensure that all of the
`residual C1—C4 aliphatic alcohol formed is removed from the
`product prior to use in a food composition since certain
`alcohols of this type (methanol, for example) are considered
`harmful when ingested.
`However, if the Can—C2,, saturated linear acyl groups in
`the csterificd propoxylated glycerin compositions of Euro~
`pean Patent Publication No. 571,219 are introduced using
`the corresponding free fatty acids rather than the C,—C,,
`alltyl esters in order to reduce the overall cost of the
`esterification, certain other processing problems are encoun~
`tered. In particular, unless an acidic catalyst such as a
`sulfonic acid is used (which may be difficult to remove
`quantitatively when esterification is completed}, a fairly
`large excess (10—30% molar cxccss) of fatty acid relative to
`the initial hydroxyl concentration must be utilized in order
`to self—catalyze the reacdon and to accomplish complete or
`near-complete esterification of the propoxylated glycerin. As
`a consequence, the excess fatty acid which remains at the
`completion of the csterification must be removed prior to
`formulation of the fat substitute into a food composition;
`excess fatty acid may cause severe taste, odor, and stability
`problems. One possible way to remove the excess fatty acid
`is by vacuum steam stripping the acids away from the
`csterified propoxylated glycerin composition. This proce—
`dure is quite difiicult to accomplish when Can-C24 saturated
`linear fatty acids are being employed since such acids are
`relatively high melting (typically, over 74° C.) and conse—
`quently readily form troublesome plugs in commercial pro-
`cessing equipment. At times, particularly in vacuum equip-
`ment, cvcn steam tracing is not an efi‘ective solution due to
`temperature-lowering effects in the vacuum eductor. As a
`result, it is often nearly impossible to carry out purification
`
`'
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`Page 2 of 6
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`

`5,466,843
`
`3
`of a CED—Cm, saturated fatty acid-esterified propoxylated
`glycerin without having to frequently shut down to remove
`plugs of unreacted fatty acid. If a transition metal esterifi-
`cation catalyst such as a zinc, titanium, or do compound is
`utilized so as to permit the use of a stoiehiomeuic amount of
`fauy acid relative to propoxylated glycerin, quantitative
`removal of the metal catalyst following esterification is often
`quite difficult to achieve. 'Ib be useable as a reduced calorie
`fat substitute in food compositions, however, the csterified
`alkoxyiated polyol must be essentially free of such metallic
`impurities.
`It is therefore evident that a great need exists for improved
`meLhods of synthesizing C20~C2,, saturated linear fatty acid-
`esterified propoxylated glycerin compositions.
`
`SUWARY OF THE INVENTION
`
`This invention furnishes a process for preparing a
`Clz—Cz, saturated fatty acid-esterified alkoxylated polyol
`comprising the steps of (a) reacting an alkoxylated polyol
`with a fatty acid source comprised of a Cn—Cz4 saturated
`fatty acid to form a crude reaction product comprised of
`unreacted C,_2—C24 saturated fatty acid and the Cu—Cz4
`saturated fatty acid-esterified alkoxylated polyol; (b) com-
`bining the crude reaction product with an aliphatic hydro—
`carbon; (c) precipitating the unreacted C32~C24 saturated
`fatty acid to form a biphasic mixture comprised of the
`precipitated CIT—C“ saturated fatty acid and a liquid phase
`comprised of the aliphatic hydrocarbon and the Cu—Cz,
`saturated fatty acid-esterified alkoxylated polyol; (d) sepa-
`rating the precipitated (Em—C24 saturated fatty acid from the
`liquid phase; and (e) separating the aliphatic hydrocarbon in
`the liquid phase from the Cza—Cz, saturated fatty acid-
`esterified alltoxylated polyol.
`In a preferred embodiment, the invention provides a
`process for preparing a behenic acid-esterified alkoxylated
`polyol comprising the steps of {a} meeting an alkoxylated
`polyol obtained by reacting a polyol having :1 hydroxyl
`groups. wherein n is an integer of 2 to 8, with from n to 10
`times 11 moles of a C2-C6 aliphatic epoxide with a fatty acid
`source comprised of behenic acid at a temperature of 150‘I
`C. to 300° C. to form a crude reaction product comprised of
`unreacted behenic acid and the behenic acid-esterified
`alkoxylated polyol; (b) combining the crude reaction prod-
`uct with a C5—C9 aliphatic hydrocarbon, wherein the weight
`ratio of crude reaction product: aliphatic hydrocarbon is
`from 1:05 to 1:10; (c) precipitating the unreacted behenic
`acid to form a biphasic mixture comprised of the precipi-
`tated behenic acid and a liquid phase comprised of the
`C5—C9 aliphatic hydrocarbon and the behenic aeid—estcrified
`alkoxylated polyol; (d) separating the precipitated behenic
`acid from the liquid phase by filtration; and (e) separating
`the C5—C9 aliphatic hydrocarbon in the liquid phase from the
`behenic acid-esterified alkoxylated polyol by distillation.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`in one step of the process of the invention, an alkoxylated
`polyol is reacted with a fatty acid source comprised of a
`Clz—CLM saturated fatty acid to form a crude reaction product
`comprised of um'cacted C ,Z—Cg, saturated fatty acid and the
`desired CIT-C24 saturated fatty acidmesterified aikoxylated
`polyol. Stumble alkoxylated polyols are well-known in the
`art and may be obtained by any appropriate med-rod includ-
`ing, for example. the alkoxylation of a polyol with one or
`more equivalents of an epoxide using a basic, acidic, or
`
`4
`
`coordination catalyst.
`The polyol may be any organic compound bearing two or
`more hydroxyl groups and preferably is aliphatic in charac-
`ter; nitrogenous, aromatic, and halide groups are preferably
`not present in the polyol. The polyol may be selected from
`C2—C1“ aliphatic diols (cg. ethylene glycol, propylene
`glycol, 1,3-propanediol, 1.4-butancdioi. 1,2-butanediol, 2,3-
`butanediol, pinacol, 1,2-cyclohexanediol, 1,2-pentanediol,
`l,¢pentanediol, i,S-pentanediol, 2,4-pentanedioi. 3,3-dimn
`ethyl-1,2-butanediol,
`2-ethyl-2-methyl-1.2-propanediol,
`1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hex-
`anediol,
`2-methyl-2,4~pentanediol,
`1,4wcyclohexanediol,
`1,7-heptanediol, 2-methyl-2i-propyl-1,3-propanediol, 2,2-di-
`ethyl—1,3—hcxandiol,
`l,2-octanediol, 1,8-octanediol, 2,2,4-
`trimethyl—l,2—pentanediol, and the like), Crete aliphatic
`trials (e.g., glycerin, 1,2,4-hutaneuiol, 2,3,4-pentanetriol,
`2-ethyl-2r{hydroxymethyl)— 1,3—propanediol, 1,1,l—tris(hy-
`droxymethleethane, 1,2,6ntrihydroxyhexane. 1,2,3-heptan-
`etriol, and the like), C,,—C12 aliphatic tetrols (e.g., sorbitan,
`erythritol, pentaerythtitol), C,,—C8 sugar alcohols [including
`those compounds corresponding to the formula HDCH2
`(CHOHJ,l CH20H wherein n is 3 to 6 such as xylitol,
`sorbitol, arabitol, mannitol, and the like}, monosaccharides
`(cg, erythose, threose, ribose, arabinose, xylose, lyxose,
`allose, altrose, glucose, ntannose, golose, idose, galactose,
`fructose, talose, and the like), disaccharides (e.g., sucrose,
`maltose, lactose} and alkyl glycosides (e.g., methyl glyco-
`sides. ethyl glycosides, propyl glycosides, and other glyco-
`side molecules wherein the alkyl glyeoside is an acetal
`formed by interaction of a C1—C20 alcohol with a carbonyl
`group of a mono- or disaocharide such as glucose). Most
`preferably the polyol is glycerin (also known as glycerol).
`The epoxide may be any organic compound containing a
`three-membercd cyclic other
`(oxirane) group. Preferred
`epoxides include C,,_—Cm epoxides, especially C2-C,i ali-
`phatic epoxidcs. such as ethylene oxide, prepylenc oxide,
`1,2-butylene oxide, [cis andi'or trans) 2,3-butylene oxides.
`isobutylene oxide,
`l,2~pentene oxide, cyclohexene oxide,
`phenyl glycidyl ether, methyl glycidyl ether, ethyl glycidyl
`ether, styrene oxide, epiehlorohydn‘n, allyl glycidyl ether,
`and the like. Due to their low cost, high reactivity, and
`favorable impact on esterified alkoxylated polyol fat substi-
`tute properties, the use of ethylene oxide, propylene oxide,
`1,2-butylene Oxide or mixtures thereof (either in random or
`block fashion] is especially desirable.
`Typically, from n to 10 n equivalents of the epoxide are
`reacted with the polyol wherein it corresponds to the number
`of hydroxyl groups on the polyol and is preferably from 2 to
`8. In preferred embodiments, the alkoxylatcd polyol has the
`general structure R—[—O(oxyalkyiene)x—H]n wherein R is an
`organic moiety derived from the polyol. oxyalkylene is a
`ring-opened epoxide unit, it is an integer of from 1 to 10, and
`n is an integer of 2 to 8. Oxyalkylene is most preferably
`oxyethylenc, oxypropylene, oxybutylene, or some combi-
`nation thereof and thus may correspond to the general
`structure
`
`ll}
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`R1 n2
`|
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`"i'f‘°'
`H H
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`wherein R1 and R2 are the same or different and are
`hydrogen or an alkyl group such as methyl or ethyl. In one
`desirable embodiment, R2 in the terminal oxyalkylenc group
`is an alkyl group since a secondary ester linkage highly
`
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`5,466,843
`
`5
`resistant to enzymatic hydrolysis will thereby be created in
`the Cm—C24 saturated fatty acid—esterilied alkoxylated
`polyol product.
`The fatty acid source to be reacted with the alkoxylated
`polyol is comprised of at least one CIz—C24 saturated linear
`fatty acid, but may be additionally comprised of other fatty
`acids such as branched. unsaturated, andfor lower carbon
`number [e.g., CFC“) fatty acids. Suitable (212—qu satu-
`rated linear fatty acids include, for example, lauric acid,
`myristic acid, palmitic
`acid,
`stearic acid, eicosanoic
`(arachidic) acid, docosanoic (behem'c) acid, and tetracosanic
`(lignoceric) acid. Mixtures of flu-(21,,4 saturated linear fatty
`acids may advantageously be employed. Such fatty acids
`may be synthetically prepared using known methods or
`obtained from natural sources such as triglycerides. For
`example, natural oils or fats containing Clo—C24 unsaturated
`ester groups may be convened to saturated form by hydro»
`genation either before or after hydrolysis. Lipids containing
`significant quantities of CAD—CM ester groups include, for
`example, high erucic rapeseed oil, meadowfoam oil, mus—
`tard seed oil, wallflower oil, fanweed oil, nasturtiurn seed
`oil, Crambe oils and the like. Preferably, at least 20 mole
`percent {more preferably at least 40 mole percent) of the
`fatty acids reacted with the alkoxylated polyol are Clz-Cw
`(more preferably, Ody—("‘14) saturated linear fatty acids,
`although up to 100% of the fatty acids reacted may be of this
`_ type if so desired. The balance of the fatty acids comprising
`the fatty acid source may be any of the other known
`saturated linear fatty acids falling outside the (Eu—(324 range
`or having unsaturated anon branched structures including,
`for example, caproic acid, caprylic acid, pelargonic acid,
`capric acid. undecyclic acid, myristoleic acid, palmitoleic
`acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid,
`cetoleic acid, erucic acid. linoleic acid, linolenic acid, and
`the Iike and mixtures thereof. Although the process of this
`invention may be carried out using the fatty acidts) and tho
`alkoxylated polyol in any proportion, it will generally be
`desirable where the Clz—Cz4 saturated fatty acid esterificd
`alkoxylated polyol is to be utilized as a fat substitute to
`accomplish substantially complete esterification of
`the
`alkoxylated polyol. That is, at least 67% and more preferably
`at least 90% of the hydroxyl groups of the alkoxylated
`polyol are preferably transformed into ester groups. Typi-
`cally, a 5 to 40% stoichoimetric excess of the fatty acid
`relative to the desired degree of csterification to be achieved
`is utilized. For example, if 80% esterification of one mole of
`a propoxylated glycerin is desired, the amount of fatty acid
`source employed is preferably from about 2.52 (“ll/toox
`1°5Am><5Jto 3.36 1(39Jioox149’tmfi) moles.
`The excess fatty acid serves to self-catalyze the estetifi-
`cation process, thus eliminating the need to employ addi-
`tional acidic or metallic catalysts. If desired, however, any
`conventional esterification catalyst could be used. The
`esterification reaction may be readily monitored by standard
`means such as hydroxyl number and the reaction halted
`when the target degree of esterification is realized.
`is
`The temperature at which the alkoxylated polyol
`reacted with the fatty acid source is not critical, but should '
`be sufiicient to accomplish the desired degree of estcrifica—
`tion within a practically short period of time (typically, 05
`to 18 hours} while avoiding substantial decomposition or
`by—product formation. The optimum temperature thus will
`vary greatly depending upon the reactants used and their
`relative proportions, among other factors, but typically tem-
`peratures in the range of from 150" C. to 300° C. (more
`preferably, 200° C. to 275° C.) will be effective where the
`esterification is being selfcatalyzed by the excess fatty acid.
`
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`The estcrification rate can be suitably enhanced by providing
`a means for removing or binding the water generated during
`esterification so as to drive the reaction to completion or near
`completion. For example, a reduced pressure of from about
`0.01 mm up to atmospheric pressure (more preferably, from
`1 to 50 turn) may be utilized to take the water overhead. An
`inert gas such as nitrogen, helium, an aliphatic hydrocarbon,
`carbon dioxide or the like may be sparged or passed through
`the reaction mixture in order to remove the water as it is
`formed. Azeotropic distillation of the water with a suitable
`azeotropic agent (entrainer) such as an aliphatic or aromatic
`hydrocarbon will also be effective for this purpose. The use
`of molecular sieves or other water absorbing or reactive
`substances may also be helpful in reducing the reaction time
`required to achieve a high degree of hydroxy group conver-
`sion. The conditions for water removal are selected such that
`a minimum amount of fatty acid is taken overhead.
`The crude reaction product obtained by esterification of
`the alkoxylated polyol, which will be comprised of pure
`acted (In—CZ, saturated fatty acid and the Cm—CZ, saturated
`fatty acid—esterified alltoxylated polyol, is combined with an
`aliphatic hydrocarbon. Preferably, the aliphatic hydrocarbon
`is nonpolar (i.e. has a low dielectric constant} and has a
`boiling point of from —20" C.
`to 175° C. at atmospheric
`pressure. In one embodiment, the aliphatic hydrocarbon is
`added to the crude reaction product when the estcrification
`has reached the desired degree of completion. In other
`embodiments, however, all or a portion of the aliphatic
`hydrocarbon is present during the course of estcrification
`since it may advantageously serve as a diluent, viscosity
`reducer, dispersant, solvent, or the like at the reaction
`temperatures typically utilized. The aliphatic hydrocarbon is
`selected such that it is relatively non-polar in character;
`preferably, it will contain from 5 to 9 carbon atoms and may
`be linear, branched or cyclic in structure. illustrative ali~
`phatic hydrocarbons appropriate for use include pentane,
`hoptane, hexane, octane, nonanc, cyclohexanc, methyl
`cyclohexane, cyclopentane, cyclooctane, dimethylcyclohex—
`ane, isopentane, neopentane, 3~methyl pentanc, isohexane,
`2,3-dimethyl butane, neohexane, 2-cthyl hexane, and the
`like and mixtures thereof including commercially available
`mixtures such as those products sold under the names
`"hexanes" and “petroleum ether".
`Sufficient aliphatic hydrocarbon is combined with the
`crude reaction product to precipitate in solid form at least a
`portion (preferably, at least 75%) of the unreacted Cu—C24
`saturated fatty acid to form a biphasic mixture comprised of
`the precipitated Cu—C24 saturated fatty acid (in solid form)
`and a liquid phase comprised of the aliphatic hydrocarbon
`and the Cu—C‘QA saturated fatty acid-esten'ficd alkoxylated
`polyol. Surprisingly, it has been found that while Cir—C24
`saturated fatty acids are diliicultly soluble in aliphatic hydro—
`carbons, Cm—C‘q, saturated fatty acid-estcrified alkoxylated
`polyols are readily soluble or miscible With such substances.
`The esterified alkoxylatcd polyol and the aliphatic hydro—
`carbon thus form a substantially homogeneous liquid phase
`which may be conveniently separated from the precipitated
`Clz—C24 saturated fatty acid.
`While the relative proportion of the aliphatic hydrocarbon
`to the crude reaction product is not critical and may be easily
`optimized by routine experimentation, the weight ratio of
`crude reaction product (exclusive of any aliphatic hydrocar—
`bon present} to aliphatic hydrocarbon is preferably from
`110.5 to 1:10. Too little aliphatic hydrocarbon may rcsult in
`a lower than desired degree of Cu—Cu saturated fatty acid
`precipitation, since the C0—C1, saturated fatty acid itself
`will generally tend to be fairly soluble in the esterified
`
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`5,466,843
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`7
`alkoxylated polyol, while the use of an excessive quantity of
`aliphatic hydrocarbon is disadvantageous due to the higher
`costs associated with removal of the excess aliphatic hydro-
`carbon from the liquid phase. To maximize the amount of
`Cut—CM saturated linear fatty acid precipitated, it will often
`be highly beneficial to reduce the temperature during the
`precipitation step as compared to the temperature utilized
`during esterification. Thus, preferably the temperature is
`lowered at least 100° C. (more preferably at least 150° C.).
`Precipitation of the Cm—Cz, saturated linear fatty acid will
`typically be most effectively accomplished within the tem-
`perature range of -—20° C. to 75" C. The temperature should
`be maintained above the temperature at which the aliphatic
`hydrocarbon freezes and the temperature at which the eateri-
`fied alkoxylated polyol begins to solidify or precipitate from
`solution.
`
`The precipitated Cu—CM saturated linear fatty acid is
`separated from the liquid phase by any of the techniques
`known in the art for separating a solid from a liquid
`including, for example. deeantation, centrifugation, or fil-
`tration. The use of filtration techniques wherein solid par-
`ticles separated from a liquid medium by use of a porous
`medium is especially desirable; such methods are well
`known and are described, for example, in “Filtration", in
`Encyclopedia ofChemica! Technology, Talcott et 211., Vol. 10,
`pp. 284-337 (1980). The recovered (312—02,, saturated linear
`fatty acid may be washed with additional aliphatic hydro—
`carbon so as to free it of esterified alkoxylated polyol. The
`fatty acid which is recovered may be conveniently recycled
`for use in further esterifieation steps.
`The liquid phase obtained as a fiitrate or supernatant is
`fractionated by any appropriate means including distillative
`means (which in this context includes evaporative means) so
`as to remove or separate the aliphatic hydrocarbon from the
`fatty acid esterified alkoxylated polyol. Where distillation is
`utilized, for example,
`the Cu—C24 saturated fatty acid-
`esterified alkoxylated polyol is provided as a bottoms or
`heavy fraction To enhance the rate of aliphatic hydrocarbon
`vaporization, super-ambient temperatures (cg, 25° C. to
`300° C.) andlor subatmospheric pressures (e.g., 0.1 up to
`760 mm Hg) may be utilized. Sparging or steam distillation
`techniques are also useful, particularly if quantitative ali—
`phatic hydrocarbon removal from the esterified alkoxylated
`polyol is desired. For food applications, it will generally be
`desirable to reduce the level of aliphatic hydrocarbon to 100
`ppm or less. A tubular coil evaporator or a film-type evapo-
`rator such as a rising film, falling film, or wiped film
`evaporater may also be used to advantage, particularly when
`the esterified alkoxylated polyol is somewhat viscous.
`The Cu—CM saturated fatty acid—esterified alltoxyiated
`polyol produced by the process of this invention can be
`additionally purified or treated so as to render it more
`suitable for use in food compositions using any of the
`techniques known in the art for refining natural vegetable or
`animal oils and fats. Such techniques include, but are not
`limited to, degtlmming, bleaching, filtration, deodoriaation,
`hydrogenation, dewaxing, and the like. Any remaining unre-
`acted fatty acid may be removed by vacuum steam stripping,
`caustic treatment, or the like. Various additives such as
`stabilizers, anti-oxidants, vitamins and so forth can also be
`incorporated into the esterified alkoxylated polyol.
`The precipitated Ola—€24 saluraled fatty acid recovered in
`the process of this invention may be economically re-used in
`subsequent esterifiearions if so desired. A significant advan-
`tage of the present process is that minimal (if any) purifi-
`cation or other treatment will be necessary to render the
`recovered fatty acids directly suitable for such reuse. In
`
`ll]I
`
`15
`
`2D
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`8
`contrast, caustic precitipation of the unreacted fatty acids
`yields alkali metal salts of the fatty acids; such salts must be
`acidified in order to regenerate the free fatty acids needed for
`esterification.
`
`From Ihe foregoing description, one skilled in the art can
`readily ascertain the essential characteristics of this inven-
`tion and, without departing from the spirit and scope meteor,
`can make various changes and modifications of the inven-
`tion to adapt it to various usages, conditions, and embodi-
`ments.
`
`The following examples further illustrate the process of
`this invention, but are not limitative of the invention in any
`manner whatsoever.
`
`EXAMPLE 1
`
`A propoxylated glycerin containing about 8 equivalents of
`reacted propylene oxide per equivalent of glycerin is com-
`bined with a mixture of ca. 85% behenic acid and 15%
`stearic acid (ca. 20—30% stoichiometric excess based on the
`hydroxyl content of the propoxylated glycerin) and heated at
`250‘1 C. and 10 mm Hg pressure for 12 hours. The crude
`reaction product (containing 12% free fatty acids) thereby
`obtained is cooled, then combined with 75 parts by weight
`hexane per 25 parts by weight of the crude reaction mixture.
`The resulting product is thereafter permitted to stand at room
`temperature so as to form a biphasic mixture. The biphasic
`mixture is filtered to obtain precipitated fatty acid in solid
`form. After removing the hexane from the filtrate (liquid
`phase) by distillation, the free fatty acid content is found to
`be only ca. 3%. The residual acidity could be further
`decreased by neutralizing the flitrate with potassium hydrox—
`ide prior to filtration. After removing the hexane, heating
`with magnesium silicate, and refiltering, the free fatty acid
`content it reduced to 0.2% (2 ppm K).
`
`COMPARATIVE EXAMPLE 2
`
`Fully hydrogenated high erucic rapeseed oil (100 parts)
`containing 15% free fatty acid (ca. 40—50% behenic acid) is
`combined with hexane (100 parts) and the mixture stirred
`and heated at reflux for 1 hour. No dissolution is apparent.
`After cooling overnight to room temperature,
`the solids
`present are recovered by filtration. Recovery is 95%; the
`recovered solids contain 12—14% free fatty acid. This
`example demonstrates that long chain saturated fatty acids
`cannot be readily separated from a triglyceride containing
`such fatty acids in ester form using an aliphatic hydrocarbon
`fractionation technique.
`
`EXAMPLE 3
`
`This example illustrates the recovery of stearic acid [Cla
`saturated fatty acid} from an esterified alkoxylated glycerin.
`A mixture of a stearic acid— esten'fied propoxylatcd glyc—
`erin containing about 8 equivalents of propylene oxide per
`equivalent of glycerin (85 parts by weight) and stearic acid
`(15 parts) is combined with hexane (100 parts). The result-
`ing mixture is heated for 1 hour with agitation 40° C. The
`mixture is allowed to stand 15 hours at room temperature
`and then for an additional 15 hours at 10° C. The precipitated
`solids are removed by filtration and the nitrate stripped of
`hexane under reduced pressure. The resulting residue is
`expected to contain about 75 parts of the stearic and estcri-
`fled propoxylated glycerin and only about 5 parts of stearic
`acid.
`
`Page 5 of 6
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`Page 5 of 6
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`

`5,466,343
`
`9
`COMPARATIVE EXAMPLE 4
`
`A mixture of 85 parts u'istearin and 15 parts stearic acid
`was added to hexane [500 parts) and refluxed for 30 minutes.
`Little dissolution was apparent After cooling,
`the solids
`were recovered by vacuum filtration. The recovered solids
`(97.1 parts) had afree fatty acid content of 14.4% indicating
`that the stearic acid was inefl’ectively separated from the
`tristearin using this technique.
`I claim:
`
`1. A process for preparing a Cu—Cz, saturated fatty
`acid—esterified alkoxylated polyol comprising the steps of:
`(a) reacting an alkoxylated polyol with a fatty acid source
`comprised of Cu—gg saturated fatty acid to form a
`crude reaction product comprised of unreacted Cu—C,“
`saturated fatty acid and the Czo—C24 saturated fatty
`acid-esterified alkoxylated polyol;
`(b) combining the crude reaction product with an aliphatic
`hydrocarbon;
`
`(c) precipitating the unreacted Cnhczq saturated fatty
`acid to form a biphasic mixture comprised of the
`precipitated Clz—Cz,‘ saturated fatty acid and a liquid
`phase comprised of the aliphatic hydrocarbon and the
`(312432,, saturated fatty acid-esterified alkoxylated
`polyol;
`(d) separating the precipitated Clz—C‘u saturated fatty
`acid from the liquid phase; and
`(e) separating the aliphatic hydrocarbon from the C,2—C2,,
`saturated fatty acid-esterified alkoxylated polyol.
`2. The process of claim 1 wherein the aliphatic hydrocar-
`bon contains from 5 to 9 carbon atoms.
`
`10
`
`15
`
`20
`
`25
`
`3. The prooess of claim 1 wherein the separation in step
`(c) is accomplished by distillation.
`4. The process of claim 1 wherein the aliphatic hydrocar—
`bon has a boiling point at atmospheric pressure of flour 20°
`C. to 175° C.
`
`35
`
`5. The process of claim 1 wherein the weight ratio of
`crude reaction product: aliphatic hydrocarbon is from 1:0.5
`to 1:10.
`
`6. The process of claim 1 wherein the alkoxylatcd polyol
`is obtained by reacting a polyol having n hydroxyl groups,
`wherein n is an integer of 2 to 8, with from _n to 10 times It
`moles of a C2—C6 aliphatic epoxide.
`7. The process of claim 1 wherein the fatty acid source is
`additionally comprised of at least one fatty acid other than
`a Gig—CM, saturated fatty acid.
`8. The process of claim 1 wherein the crude reaction
`product is comprised of from 0.01 to 1 mole of unreacted
`Ciz—Cm saturated fatty acid per mole of C124324 saturated
`fatty acid-esterified alkoxylatcd polyol.
`9. The process of claim I wherein step (a) is performed at
`a temperature of from 150“ C. to 300° C.
`10. The process of claim 1 wherein step (a) is performed
`at subatmospheric pressure.
`11. The process of claim 1 wherein the CHE—(12., saturated
`fatty acid is selected from the group consisting of lauric acid,
`myristic acid, palmitic acid, stearic acid. aracltidic acid.
`lignoccric acid and behenic acid.
`12. The process of claim 1 wherein at least 15% of the
`unreacted Cn—CM saturated fatty acid is precipitated in step
`
`45
`
`50
`
`55
`
`10
`
`(c)