Vegetable fatty oils are products extracted from oil raw materials and consisting mainly (for 95-97%) of organic compounds, compound acids full of glycerin ether and fatty acids. Waxes and phosphatides as well as free fatty acids, lipochromes, tocopherols, vitamins and other substances imparting color, taste and smell are the parts of fatty oils. Apricot, grape, castor, cedar, hempseed, linen, macadamia nut, almond, olive, palm, peach, sunflower-seed, pumpkin and many other oils belong to fatty vegetable oils.
Fatty oil properties are defined mainly by the composition and content of fatty oils. Usually they are saturated and unsaturated (with one, two and three double bounds) monoatomic fatty acids with carbon series circuit and even number of carbon atoms (mainly C16 and C18).
Depending on the content of unsaturated fatty acids the consistence of oils and the temperature of congelation change: the temperature of congelation of liquid oils containing more unsaturated acids is below zero, of solid oils it reaches 40 °С. Only oils of some tropical plants (palm for example) belong to solid oils. When contacting with air many liquid fatty oils undergo polymerization by oxidation ("dry up"), forming scum. According to the ability for "drying" oils are divided into a number of groups based upon primary content of these or that unsaturated acids, for example oils drying like linen oil (linen-like drying) contain mainly linoleic acid. Castor oil containing mainly ricinol acid doesn't form any scum at all.
Oils are capable of dissolving gases, sorb volatile matters and essential oils. An important oil property (except for castor oil) is their ability to mix in different proportions with most of organic solvents (hexane, benzene, benzol, dichlorethane and others), which is connected with low polarity of oils. Oils practically don't dissolve in water.
The major biological value of vegetable oils is high content of polyunsaturated fatty oils, phosphatides, tocopherols and other substances in them. The overall quantity of phosphatides is in soy, cotton, sunflower-seed and corn oils. The total content of tocopherols is not the vitamin value characteristic of oil.
The main ways of fatty oil manufacture are extraction and extracting. General preparatory stages for both ways are cleaning, drying, decortication of seeds' rind and its separation from the kernel.
Vegetable oils manufactured by any method undergo purification. According to the degree of purification food fatty oils are divided into raw, non-refined and refined. Partly purified oils, those which undergo setting, filtration, hydration and neutralization belong to non-refined oils.
The fields of application of oils are numerous.