Oleum Theobromatis. U. S., Br. Oil of Theobroma.
Ol. Theobrom. [Butter of Cacao, Cacao Butter]
"A. concrete fixed oil obtained from the roasted seeds of Theobroma Cacao Linné (Fam. Sterculiaceae)." U. S. "Oil of Theobroma is a solid fat expressed from the seeds of Theobroma Cacao, Linn." Br.
Oleum Theobroma, U. S. 1880; Cocoa butter (improperly); Beurre de Cacao, Fr. Cod.; Oleum concretum e semine Theobromae Cacao, Fr.; Oleum Cacao, P. G.; Kakaobutter, G.; Manteca de coco, Aceite de coco, Sp.
Theobroma Cacao Linn. is a handsome tree, from twelve to twenty feet in height, growing in Mexico, the West Indies, and South America. It is largely cultivated in all tropical countries, particularly in Guayaquil, Venezuela, Mexico, Trinidad, and the Philippines. The fruit is an oblong-ovate capsule or berry, six or eight inches in length, with a thick, coriaceous, somewhat ligneous rind, enclosing a whitish pulp, in which numerous seeds are embedded. These are ovate, somewhat compressed, about as large as an almond, and consist of an exterior thin shell and a brown oily kernel. Separated from the matter in which they are enveloped, they constitute the cacao, or chocolate nuts, of commerce. The cacao tree is usually cultivated in large estates, where it is grown in the shade of the banana or other large plant, and develops its pods from the stem continually, so that the harvest goes on all the time, although the product is greater in the spring and in the autumn. The pods are cut off, opened, and the beans contained in the glutinous sweet acid pulp are allowed to ferment, during which process the outer integument comes off easily. The beans are finally carefully dried, commonly in the sun, sometimes by means of a steam drying shed. If the sweating process is carried too far, or the beans during drying are wetted by rain, they blacken and are much lowered in value. These blackened beans are sometimes artificially whitened. Cacao beans have a slightly aromatic, bitterish, oily taste, and, when bruised or heated, an agreeable odor. (See Am. Drug., 1897, 311; also Ph. Ztg., 1900, 756.)
The average of a number of analyses of raw nuts gave H. Weigmann (König's Nahrungs- und Genussmittel, 3d ed., vol. i, 1019) water, 7.93 per cent.; nitrogenous matter, 14.19 per cent.; theobromine, 1.49 per cent.; fatty matter (cacao butter), 45.57 per cent., starch and other carbohydrates, 22.92 per cent.; crude fiber, 4.78 per cent.; pure ash, 3.99 per cent.; sand, 0.62 per cent. The coloring matter is probably the result of chemical change, as the fresh seeds are white. Theobromine has been found also in the shells in the proportion of about 1 per cent. (A. J. P., 1862, 509.) The latter impart to boiling water a taste analogous to that of chocolate, but weaker, and are used for making a table beverage.
Theobromine was discovered by Woskresensky, who obtained it by the following method. The kernels are exhausted with water by means of the water bath; the solution is strained through linen, precipitated by lead acetate, and filtered; the filtered liquor is freed from lead by hydrogen sulphide, and evaporated; the brown residue is treated with boiling alcohol, and the liquor filtered while hot. Upon cooling, the theobromine is deposited in the form of a reddish-white powder, which is rendered colorless by repeated crystallization. Keller obtained it still purer by heating the powder between two watch glasses, by which a brilliant white sublimate was obtained. According to O. Donker and C. Treumann, theobromine is contained not only in the cotyledons but also in the shells of the cacao seeds. Four kilos of the latter yielded 13.5 Gm. of pure theobromine. Theobromine is now official.
For Emminger's method of determining theobromine in cacao, see P. J., 1896, 289.
Cocoa or Prepared Cacao is also official in the N. F. IV under the title Cacao Praeparata. The description and tests are as follows:
"A powder prepared from the roasted, cured kernels of the ripe seeds of Theobroma Cacao Linné and of other species of Theobroma (Fam. Sterculiaceae), deprived of a portion of its fat. A brownish powder having a chocolate-like odor and taste, free from sweetness. Extracted with cold water Cocoa yields not less than 14 per cent. nor more than 22 per cent. of soluble matter. Extracted with ether, Cocoa yields not less than 18 per cent. of fat, and the fatty residue does not have a spicy odor or taste. The residue, insoluble in ether, when examined under the microscope, shows not more than 3 per cent. of Cocoa shells, and no foreign starch granules or other foreign substances. Cocoa contains not more than 6 per cent. of crude fiber and not more than 12 per cent. of starch. Cocoa yields not less than 3.5 per cent. nor more than 8 per cent. of ash, which has a distinctly reddish color." N. F.
Cacao, usually but erroneously known as cocoa, is often sold in powder which is sometimes adulterated with various other ingredients such as ground rice, barley flour, sugar, etc. Mixed with hot milk or water it is much employed as a drink. It has the advantages over tea and coffee that it is less stimulating to the nervous system and contains some nutriment. Chocolate is the solid substance expressed from the cacao bean after roasting. In Great Britain and the United States it is usually made, when pure, exclusively of the kernel of the cacao or chocolate nuts, which are first roasted, then deprived of their shells, and lastly reduced, by grinding between heated stones, to a paste, which is moulded into oblong cakes. Sometimes rice flour or other farinaceous substance, with foreign fats, is added, but these must be considered as adulterations. In the compounded form known as sweet chocolate, sugar is generally incorporated with the paste, and spices, especially cinnamon, are often added; vanilla is a favorite addition in America, France, and Spain. The well-known confection known as "milk chocolate" contains either whole or skim milk powder in addition to the foregoing ingredients. The U. S. Department of Agriculture standards for cocoa products are as follows:
"1. Cocoa beans are the seeds of the cacao tree, Theobroma cacao, L.
2. Cocoa nibs, cracked cocoa, is the roasted, broken cocoa bean freed from its shell or husk.
3. Chocolate, plain chocolate, bitter chocolate, chocolate liquor, bitter chocolate coatings, is the solid or plastic mass obtained by grinding cocoa nibs without the removal of fat or other constituents except the germ, and contains not more than three (3) per cent. of ash insoluble in water, three and fifty hundredths (3.50) per cent. of crude fiber, and nine (9) per cent. of starch, and not less than forty-five (45) per cent. of cocoa fat.
4. Sweet chocolate, sweet chocolate coatings, is chocolate mixed with sugar (sucrose), with or without the addition of cocoa butter, spices, or other flavoring materials, and contains in the sugar- and fat-free residue no higher percentage of either ash, fiber, or starch than is found in the sugar- and fat-free residue of chocolate.
5. Cocoa, powdered cocoa, is cocoa nibs, with or without the germ, deprived of a portion of its fat and finely pulverized, and contains percentages of ash, crude fiber, and starch corresponding to those in chocolate after correction for fat removed.
6. Sweet cocoa, sweetened cocoa, is cocoa mixed with sugar (sucrose), and contains not more than sixty (60) per cent. of sugar (sucrose), and in the sugar- and fat-free residue no higher percentage of either ash, crude fiber, or starch than is found in the sugar- and fat-free residue of chocolate."
Hagenbuch examined several commercial brands of chocolate, and found that the amount of fat or cacao butter present varied from 12 to 45.8 per cent. (A. J. P., 1885, p. 276.) From this it would seem that manufacturers do not uniformly extract the fat from commercial chocolate.
Oil of Theobroma. Cacao Butter.—This is the fixed oil of the chocolate nut. It is extracted either by expression, decoction, or the action of a solvent. Soubeiran recommends that the seeds, previously ground, be mixed with one-tenth of their weight of water and then pressed between hot plates of tinned iron. It is advisable that the heat should not exceed that of boiling water, and even a lower heat will answer. When the method of decoction is used, the cacao should be slightly roasted before boiling. As a solvent, carbon disulphide has been found to answer well, as recommended in the preparation of the expressed oil of nutmeg. (See Oleum Myristicae.) Upon the whole, the method of expression is perhaps preferable. The presence of water in the ground seeds is said greatly to facilitate the process. The expressed oil, now made largely in Philadelphia as a by-product in the manufacture of cocoa, occurs in the shape of oblong cakes, like those of chocolate, weighing about half a pound each. It is "a yellowish-white solid, having a faint, agreeable odor, and a bland, chocolate-like taste. It is usually brittle at temperatures below 25° C. (77° F.). It is slightly soluble in alcohol, soluble in boiling dehydrated alcohol, and freely soluble in ether, chloroform or benzene. Specific gravity: about 0.973 at 25° C. (77° F.). It melts between 30° and 35° C. (86° and 95° F.). Dissolve 1 Gm. of Oil of Theobroma in 3 mils of ether in a test tube at a temperature of 17° C. (62.6° F.), and immerse the tube into water having the temperature of melting ice. The liquid does not become turbid nor deposit white flakes in less than three minutes; and if the mixture after congealing is again brought to 15° C. (59° F.), it gradually forms a perfectly clear liquid (wax, stearin, or tallow). Saponification value: not less than 188 nor more than 195. Iodine value: not less than 33 nor more than 38." U. S.
"A yellowish-white solid, breaking with a smooth fracture. Odor resembling that of cocoa; taste bland, agreeable. Somewhat brittle at ordinary temperatures, but softening at 25° C. (77° F.). Specific gravity 0.990 to 0.998; melting point 30° to 33° C. (86°-91.4° F.); saponification value 188 to 195; iodine value 35.5 to 37.5; acid value not more than 2.0; refractive index at 40° C. (104° F.) 1.4565 to 1.4575. In ascertaining the melting point and specific gravity, seventy-two hours should be allowed to elapse between the time of melting and the time of determining the constants. When 1 gramme is dissolved at 17° C. (62.6° F.) in 3 millilitres of ether in a test-tube, and the tube placed in water at 0° C. (32° F.), the solution neither becomes turbid nor deposits a granular or flaky mass in less than three minutes; and if, after congealing, it is exposed to a temperature of 15.5° C. (60° F.), a clear solution is gradually formed (absence of certain other fats)." Br.
Cacao butter consists chiefly of the glycerides of stearic, palmitic, and lauric acids, and, further, of small quantities of the glycerides of arachidic, linolic, formic, acetic, and butyric acids. The percentage of stearic acid obtainable is from 39.9 to 40.6. Kingzett believes it to contain in addition a peculiar acid which he calls theobromic, and to which he gives the formula C64H128O2, but his results have not been confirmed by subsequent investigators. From its large proportion of stearin, it is one of the best fate for the preparation of stearic acid. It is said to be frequently adulterated with animal fats, which, according to E. Lamhofer, may be detected by attention to the fact that pure cacao butter dissolves entirely in ether or petroleum benzin, separating out in minute granular crystals when immersed in water of 0° C. (32° F.), the liquid portion remaining transparent for 30 or 40 minutes, when the whole solidifies. After solidification, if the oil be kept at a temperature of about 14.4° C. (58° F.), it will redissolve without turbidity. (A. J. P., 1877, p. 238.) G. Ramsperger concludes, as the result of much experimentation, that ether affords the best test of purity (see the official tests).
Uses.—Butter of cacao is used as an ingredient in cosmetic ointments, and in pharmacy for coating pills and preparing suppositories. For the last purpose it is well adapted by its blandness, and the fact that although liquefying at a temperature below that of the body, it is of firm consistence at 21.1° C. (70° F.). It is also valuable for the reason that easily decomposable substances like silver nitrate, potassium permanganate, etc., may be incorporated in it without material change and it is therefore valuable as an excipient. It was chiefly on this account that it was introduced into the U. S. Pharmacopoeia of 1860. It has the emollient properties of the fats and is used to soften and protect chapped hands or lips. F. Bringhurst prepared a lip salve by melting together 28 ounces of cacao butter, 4 ounces of yellow wax, and a drachm, each, of balsam of Peru and benzoic acid, straining, adding perfuming oils, as those of rose, bergamot, and bitter almond, in sufficient quantity, and finally, when nearly cool, an ounce of glycerin. (A. J. P., July, 1867, p. 348.)