The oil is obtained from the seed of the sunflower (Helianthus annuus L.). It is of a pure amber tint with an agreeable odor and pleasant taste. As has already been said it is grown largely in Russia and also in Indo-China. The seeds are very rich in oil. Before expression the hulls should be removed, since these form a porous substance, and if the seeds are crushed with the hulls large quantities of oil are absorbed and cannot be recovered.
The method of preparation is the same as that for other edible oils, the kernel, after the removal of the hull, being ground and cold-pressed for the highest grade. By heating and renewing pressure lower grades of oil are secured suitable for soap making. Where all the oil is required the extraction with bisulfid of carbon or gasoline is advised. Such oils, however, are not suitable for edible purposes because of the difficulty of removing the last traces of the solvent. The specific gravity of sunflower oil at 15 degrees is approximately .925. It absorbs a very high percentage of iodin, and in this respect it may be classified with the drying oils. Its iodin number ranges from 120 to 130. No specific color reactions have been established by means of which sunflower oil may be readily distinguished from the other edible oils.
In fact sunflower oil has not been subjected, by any means, to as critical a study as many other vegetable oils.
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-
