Vegetable Fats.
The fatty principles in vegetables which are solid at ordinary temperatures are commonly termed fats instead of oils. They present, as a rule, a soft mass, usually of an amber tint and somewhat of the consistence of butter. Only a few of these solid fats or semi-solid fats are used for food. Among them the most important are palm-nut oil or coconut oil or fat, though the fat of the cacao also may be regarded as belonging to this group. These solid or semi-solid fats are used to a considerable extent for edible purposes in many parts of the world. Coconut fat and cacao fat are used very extensively in this country either in a pure state or in chocolate or cocoa.
Cacao Butter.
—Cacao butter is the semi-solid fat obtained by pressure from cacao beans, the seeds of the cacao tree (Theobroma cacao L.). These beans are extremely rich in fat, the content of which varies from 35 to 50 percent. On a large scale the cacao beans are roasted, ground, and the fat expressed while still hot by hydraulic pressure. In order to remove the free acid which it contains the carbonates of the alkalies are mixed with the material after grinding and before extraction. In these cases the expressed fat naturally does not contain any free acid, though the soaps which are formed by this process are apt to contaminate the expressed fat.
Adulterations.
—By reason of its high price cacao butter is often adulterated by the addition of various fats usually of a vegetable character. Those most generally employed are the stearin derived from the coconut fat and the palm-nut fat. The addition of ordinary edible vegetable oils is easily detected by the usual chemical tests and is especially recognized by the increase in the percentage of iodin absorbed. They also reduce the melting point of cacao butter, and for this reason these oils, with the exception of coconut, are not used very extensively as adulterants. Beeswax and paraffine wax are also used to some extent as adulterants, and when used in connection with vegetable oils they serve to keep the melting point from going too low. Tallow has also been used quite extensively as an adulterant. The detection of these adulterants is so difficult as to be accomplished only by a skilled chemist.
Composition.
—Cacao butter is composed chiefly of stearin and palmitin, though other fats and oils are present in small quantities. Although it is generally supposed that cacao butter does not tend to become rancid, this is a mistake, since, when exposed to the conditions which favor rancidity, the fermentation which produces this condition takes place in the butter, though somewhat more slowly and more incompletely than in many other fats. The specific gravity of cacao butter at 50 degrees C. is .892. It absorbs about 35 percent of its weight of iodin. It has a much lower melting point than palm fats and even lower than butter. Its melting point varies from 30 to 33 degrees C. Cacao butter has some of the properties of ordinary butter and has been recommended as a substitute therefor, but it is not likely that it will ever come into common use both because it is less desirable than butter and also because of its high price.
Properties.
—Cacao butter has a light amber tint and tends to become bleached on long standing. It has a very pleasant flavor, reminding one of the flavor of the preparations of chocolate. At ordinary temperature, 70 degrees F., it is quite solid and sometimes even brittle.