Oleum Sesami, I.C.A. Sesame Oil.
Sesame oil, Gingelly oil, Gingilli oil, or Teel oil, is obtained by expression from the seeds of Sesamum indicum, Linn. (N.O. Pedalineae), the sesame plant, largely grown in India, China, Japan, and, most tropical countries. The yield of oil is from 50 to 57 per cent. It occurs as a limpid, oily liquid of pale yellow colour, having a pleasant grain-like odour and a bland taste. Specific gravity, 0.921 to 0.924; congeals at about -5°. Rotation slightly dextro-gyrate, from about +1° to +9°. The common adulterants of sesame oil are poppy-seed oil, arachis oil, cotton-seed oil, and rape oil. Saponification value, 189 to 193; iodine value, 103 to 108.
Constituents.—The oil consists essentially of the glycerides of oleic and linoleic acids, with small proportions of stearin,. palmitin, and myristin. Sesamin, C18H18O5. another constituent of the oil, may be obtained in long crystalline needles melting at 118°; rotation +68° 36°; insoluble in water, light petroleum, ether, alkalies and mineral acids; easily soluble in chloroform, benzene, and glacial acetic acid. To this substance and to phytosterol is due the optical activity of the oil. Besides these bodies, sesamol, a phenol, is said to be present. The solid fatty acids are present to the extent of 12 to 14 per cent.; the liquid fatty acids, about 70 per cent. It further contains a very characteristic substance, which serves as an almost infallible means of identification of the oil, or its admixture with other oils, even in very small percentages, by the following test:—Dissolve 1 decigram of sugar in 10 mils of hydrochloric acid of specific gravity 1.160, in a test-tube, and add 20 mils of the oil to be tested; shake well, and allow to stand. In the presence of even minute quantities of sesame oil the separated aqueous liquid will have a crimson colour. In place of the sugar, 0.1 mil of a 2 per cent. alcoholic solution of furfural may be used. This is known as Baudouin's test. The chromogenetic substance passes completely into the liquid fatty acids when these are separated in the usual way, and is not destroyed by heating the oil to 200° to 250° for ten or twenty minutes.
Uses.—Sesame oil is used in the preparation of additive compounds of iodine and bromine, iodinol (Iodipin) and brominol (Bromipin), which are employed for external, internal, or subcutaneous use. The best qualities of the oil are largely used in he manufacture of margarine. Sesame oil may be employed as a substitute for olive oil in making the official liniments, ointments, and plasters, in India, and the African, Eastern and North American Colonies.