Only the best variety of cold-drawn sesamé oil is used for edible purposes and for making oleomargarine. The inferior qualities are used in soap making, the making of perfumes, etc., and the lowest quality of oil is used for burning purposes.
Characteristic Reaction.
—A test which is known as Baudouin’s is extremely delicate and reliable and is easily applied. It consists in the development of a red color when a small quantity of sesamé oil is treated with hydrochloric acid in the presence of furfural. The test is easily carried out as follows: Place a few drops of a two percent solution of furfural in a test-tube with 10 cubic centimeters of sesamé oil or the oil to be tested for sesamé and 10 cubic centimeters of hydrochloric acid of 1.19 specific gravity, and shake the mixture well for half a minute. When the tube is left at rest, if sesamé oil be present the aqueous acid layer which forms will have a distinct crimson color. Any coloration which is produced by other oils is entirely distinct from this one and therefore can be easily distinguished.
Geographical Distribution.
—The sesamé plant is grown chiefly for commercial purposes in India, China, Japan, and West Africa. The technical preparation of the oil, in so far as is known, is not practiced in the United States. It is pressed and prepared for commerce chiefly in France. The seeds are rich in oil, yielding a larger percentage by pressure or extraction than most of the oil-bearing seeds.
Sunflower Oil.
—The oil extracted from the seed of the sunflower is of high quality for edible purposes. Although not in general use in this country, it is very extensively used in Russia and some other parts of Europe. There is every reason to believe that a profitable industry could be established in the preparation of edible oils from sunflower seeds. The plant grows in the greatest luxuriance in nearly all parts of the country, and the yield is sufficiently great to make it an object of more interest to our agricultural population than it is at the present time.
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.