[1]Utiited States Patetit Office 3yOi22890 3,012,890 SYNTHF,TIC COCOA BUTTER SUBSTITUTE Heeaert J. Dutton and Charles R. Scbolfield, Peoria III assi-nors to the United States of America as represented by the Secretary of Agiieulture No Drawing. Filed Feb. 3, 1960, Ser. No. 6,572 I Claim. (Cl. 99-118) (Gmnted under Title 35, U.S. Code (1952), see. 266) A nonexeltisive, irrevocable, royalty-free license in the invention herein described, throughout the world fOT all purposes of the United States Governmen', with the power to grant sublicenses for such purposes, is hereby granted to the Govemment of the United States of America. This invention relates to a novel method of producing synthetic cocoa butter and closely related oleaginous substitutes from inexpensive raw materials. Cocoa butter is a fat having unusual physical properties. It melts completely at 33'-34' C. or slightly below body temperature, and is a hard brittle solid at normal room temperatures. Because of transitions of polymorphic crystalline -forms it displays two me.ting points after rapid chilling. The first form melts at 25' C., then Tesolidif@es as the temperature slowly rises and rnelts once more at 33'-34' C. corresponding to the second polymorphic form. Cocoa butter is Lised in confectionery products largely because its physical properties contribute glossy coatings, absence of stickiness, and favorable volume changes in the molding operation for the enrobed confection. Procedures for slightly raising the m.-Iting point of cocoa butter to prevent bloom at summer temperatures are known in the art. Cocoa btitter is also widely used, thou,-h in small volume, as a suppository vehicle. That the unique melting characteristics of cocoa butter are a consequence of the arran,@omeit of the fatty acids in its g@lycerides is illustrated by a comparison of cocoa butter with mutton tallow which is similar to it in fatty acid composition but unsuitally different in physical properties. Because of demand for the properties which cocoa butter imparts, large quantities of this dollar-per-pound commodity are importcd even when domestic fats at less than one-fifth the cost are i-@i pleqtiful supply. The triglyceride composition and structure of cocoa butter have previously been investigated using fractional crystallization techniques and the results have been interpreted to su.@@est that the structure represents an even" distribution of oleic, palmitic, and stearic acid triglycerides. By use of countercurrent distribution and application of -more than 1,000 extraction stages, we have discovered that a specific "modified random" rather than an ."even" pattern characterizes cocoa butter and is responsible for its characteristic melting points and other specific properties. Employing a solvent system consisting of 3.8 liters of furfural and 3.8 liters of nitroethane equilibrated with 10 liters of pentane-hexane in a 200-tube Craig countercurrent apparatus, carried to 1150 transfers by recycling, we have discovered the specific disposition of the glycerides of cocoa butter. Palmito-oleo-steariia is present to the extent of 41 percent and is the main triglyceridt,. We found tristearin to comprise only 0.!16 percent of the total cocoa butter glycerides. We have further discovered that the palmitic and stearic acid moieties are randomly distributed on the I and 3 posit,'@ons o-f the glycerides. Thus, we have found that except for a small PeTCeilta,@e of trisaturates and linoleic acid-containing glycerides, oleic acid occurs at least once in each glyceride niolecute. Cocoa butter comprises principally monoolefins, Patented Dec. 12, 1961 2 namely oleodistearin, 22 pereent; oleopalmitostearin, 41 percent; and oleodipaimitiii, 12 percent. Since the latter alyceride is not permitted under a pure "even" distribution pattern and the low trisaturates content is inconsistent with a random distribution pattern of fatty acids, it is clear that cocoa butter follows neither a strict random nor a strict "even" pattern of glyceride structure. In agreement with recent enzymatic studies of others indicating that oleic acid occurs predominately in the 2 10 position of glycerol molecules, our results show cocoa butter to be predominately composed of glyceride molecules containing at least one oleic acid unit per molecule. Further, our countercurrent distribution fractionation results are consistent with a random distribution of pa-Imitic 15 and stearic acids on the I and 3 positions of glycerol. Numerous variants exist iii t'@ie condudt of our cocba butter synthesis. By varying the ratios of palmitic and stearic acid iii thetriglycerides used for direct,- d interesterification, diglyceride and subseqliently triglyceride 20 mixtui7es of varying composition are obtained with m6dified nielting point and other physical properties. In cornmercial practice, natural fats containing palmi,ic, stearic and C,8 unsaturated fits would be used as starting points for diglyceride synthesis. For examdle, 25 hydrogeiiation of lard would yield a 3-4:1 proportio-q of stearin to palmitin. By single solvent crystallization or other known crystallization procedures the palmitic acid content of lard may be raised to 50 poreent. In a siriailar nianner other fats such. as palm oils n-@ight be 30 directly hydrogenated or fractiongted to increas-2 palm@'@tic acid and subsequently hydrogenated. For expinple, soybean oil hydrogenated without crystallization wou@ld give a 9:1 stearic to palmitic ratio and the synthetic cocod butter product would have a higher melting point than 35 the natural cocoa butter, which is desirable for use in enrobing candy in warm climates. Direct isolation of saturated diglycerides from a natural fat in a single step process may also be achieved in commercial practice. Appropriate glycerol and in40 teresterification catalyst have been added to l@@rd and the temperature lowered from 120' F. as described by Baur and Lan.-e (J.A.C.S. 73: 3926 (1951)) under conditions of directed interesteri-fication to yield crystalline 45 diglycerides di@rectly. Completion of the esterification to triglycerides by oleyl :chloride can then be carried out as described in the examples. Since lard and cocoa biitter have comparable fatty acid com@positions the problen-i of converting this 10 cents per pound product to a $1.00 per pound product is simply a problem of the rearrange50 ment of position of fatty acids on the -,Iycei-ol molecule. Under this concept direct formation of the 1,3-palmito stearo diglyceride from lard by directed interesterification and recovery of the olein would be the first step. Conversion of the olein with oleyl chloride and resynthesis 55 of the triglyceride would be a second step. Alkali refining and deodorization would complete the process r rearranging lard into cocoa butter. Based upon the above findin.-S and interpretations we synthesized a cocoa butter substitute, as set forth in Ex60 ample 1 below, employin-, the Baur and Lange procedure for pure monoacid di.alycerides but employing an equal qti,antity of tripalmitin and tristearin instead of using a single pure triglyceride. A random mixture of dipalmityl, distearyl., and palmityl stearyl 1,3-diglycerides was thus 65 synthesized. The synthesis of the cocoa butter substitute was completed by acylation of the, 2-hydroxyl with oleyl chloride. EXAMPLE I 70 Tripqlmitin (4.42 gm.), tristearin (4.88 gm.), and triacetin (6.75 gm.) were melted and held with stirring for 2 hours at 60' C. under an inert gas after adding 4
[2]3 mt. of sodium methoxide catalyst (0.0208 gm./ml.) (Eckey, TJ.S. Pat. 2,442,531). To the homo-.encous reaction mixture was then added 1.74 ml. of dry glycerol and heating was continued for 24 houts. Then in steps at 2-day intervals, the temperature was lowered to 46', 38', 32', and 27' C. After the addition of 2 drops of glacial acetic a-,id, the mixed 1,3- diglycerides were crystallized from heptane-ethanol (1:1) and dried, providing the selective recovery of stearic and palmitic acid-co-iltainin.- diglycerides. Acylation of the 2-hydroxyl groups was carried out by reacting 2.2 gm. oleyl chloride with 3.5 gms. of the 1,3-mixed glycerides at a pressure of 2 min. and temperature of 100' C. The synthetic cocoa butter melted at 3 1 '-3 2' C., h ad an iodine value of 3 3.9, and a fatty acid composition of 18.2 percent palmitic, 40.8 percent stearic, and 41.0 percent oleic acids. When mixed with natural cocoa butter in 25 and 50 percent proportions, dual n-ielting points were found at 24.5' C. and 32-33' C. EXAMPLE 2 Preparation of syiithetic cocoa-butter Twenty and three-tenths grams of tripalmitin and 20.3 grams of tristearin were mixed with 22.2 g. of triacetiu and 16 ml. <)f NaOMe (0.0208 g./ml.). This mixture was allowed to melt at 1 10' C. and maiptained with constant stirring for two hours, at which time 6 ml. of dry glycerol was added. Heatii.- at 60' C. was continued for one day. The temperature was then lowered to 47' C. and maintained for two days. It was then slowly lowered over the period of one day to 32' C. and then slonvly during another 24 hours to room temperature. Crystals began to form at about 37' C. The mixture was taken up in 200 ml. of 1: 1 n-heptane, 95 percent ethanol and 2 ml. of glacial acetic acid and al.iowed to crystallize from the solvent first at room temperature and then at 2' C. for an hour. The crystals were collected on a Buchner funnel. The filtrate was concentrated by evaporation and more crystals formed at 2' C. 31012,890 4 The two fractions of diglyceride crystals were analyzed and then combined. Total yield of diglyceride was 37.86 grams or 93.25 percent of original. Compositi-on: 45.69 percent palmitate and 54.31 percent stearate. ti Thirty-four a-@id six-tenths -rams iDf the 1-3 randomly distributed diglycerides Nvere reacted with 22.0 grams of oleyl chloride at 1.2 mm. of pressure and at 100- 150' C. for t,,vo hours. The resulting sample was dissolved in etber, decolorized using carb-on black, filtered on a Buch10 ner funnel, and the solvent evaporated, Yield 47.2 gms., iodine valtic 31.8, palmitic acid 29.5 percent, stearic acid 37.3 percent, oleic acid 36.0 percent, melting point 34'-37' C. A portion of this preparation was refined with soda ash and stean-i deodorized to give a bland prod15 uct as determined by a taste panel. H,,tvin@ thus fully disclosed r ention, we
