Sesame – Sesamum indicum L.
Distribution – South and Southwest tropical Africa. Cultivated in tropical and subtropical states of both hemispheres (including the USSR – Central Asia, Kazakhstan, etc.). Sesame is one of the oldest cultivated oil plants. polymorphic look.
Plant 1-1.7 m tall, pubescent with glandular hairs. Stem 4- or 8-sided, branched in most forms. Lower leaves on long petioles, 3-6-parted, lobes ovate-lanceolate, serrated along the edge; upper leaves lanceolate. The flowers are large, axillary, solitary or in bunches of 3-5 flowers. Corolla strongly pubescent, white, pink, with a purple bloom or cream, falling off in the evening. The fruit is an elongated capsule containing up to 80 seeds. The seed is flat, ovoid, small, of various colors – from white to black.
Seeds (Semen Sesami) contain 40-60% fatty non-drying oil; after refining, it is devoid of smell, pale straw color, pleasant taste. Triglycerides of oleic acid in oil within 50%, linoleic acid – 35%, limit – up to 15%. Iodine number 102-117. The highest grade of sesame oil (Oleum Sesami) is used as a solvent for camphor and other medicinal products. The importance of sesame oil as one of the best edible oils is well known.
The plant contains liquid fats (oils).
PLANTS CONTAINING FATS (FATTY OILS)
Fats consist almost entirely of triglycerides of high molecular weight fatty acids. They are accompanied by pigments, sterols, vitamins and some other fat-soluble substances.
The fatty acids that make up triglycerides can be saturated or unsaturated. Most often, triglycerides contain the fatty acids listed in the table.
Fats are not individual substances – they are mixtures of triglycerides. In the formation of fats, the law of maximum heterogeneity prevails – more than 1300 currently known fats are formed by “multi-acid” triglycerides, and fatty acids of different composition (for example, stearinodiolein, palmitinooleinolinolein, etc.). Fats, consisting of “one-acid” triglycerides, are relatively rare in nature (olive oil is triolein, castor oil is triricinolein).
The properties of fats are determined mainly by the composition of fatty acids and their quantitative ratio. Saturated fatty acids form triglycerides of a dense consistency (at traditional temperature), and the density increases with the increase in the number of carbon atoms in the acid (see table). Unsaturated fatty acids form liquid triglycerides.
Liquid fats (oils), spread with a thin layer, can remain liquid (non-drying fatty oils) or, oxidized, gradually turn into a resinous film (drying – a dense film and semi-drying – a soft film). Fatty oils dominated by oleic acid triglycerides are non-drying. The more linoleic and linolenic acids in oils, the more they are prone to drying out, as can be judged by the iodine number (the number of grams of iodine that can join 100 g of fat at the place of double bonds of unsaturated acids). Approximate limits of iodine numbers: non-drying 80-100, semi-drying 100-140, drying oils 140-200.
Most vegetable fatty oils are obtained by pressing or extracting raw materials with volatile solvents. Freshly obtained (“raw”) fats are purified (refined).