GB764833A - Improvements in or relating to treatment of glyceride oils - Google Patents

Abstract

<PICT:0764833/III/1> Fatty oils containing gums and free fatty acids are purified by mixing with the oil, separately or as an aqueous solution, a quantity of a volatile alkali and a quantity of water sufficient to precipitate at least some of the gums of the oil as hydrated volatile-alkali gums, and separating mixture into an oil phase and an aqueous phase containing the hydrated gums. The alkali may be ammonia, monomethylamine or dimethylamine. Sufficient ammonia may be used to react with part or all of the free fatty acids to produce soaps. The ammonia may be separated as vapour from the aqueous phase and re-used. The separated gums or gums mixed with fatty acids may be used for many purposes, e.g. as emulsified and antioxidants. In a plant for de-gumming only, the oil from a tank 10 and ammonia solution from a tank 20 in controlled amounts are mixed and passed through a heater 14 and an agitator 16 to a separator 17 such as a centrifuge, to produce degummed oil at 24 and ammoniated gums at 25. Only a small amount of ammonia is required. Gaseous ammonia may be used from tank 20, water being supplied from tank 31. The gums discharge to a vacuum still 26 for recovering the ammonia and water, which are condensed in 28 for re-use. A larger amount of ammonia may be used to react with the free fatty acids to produce an aqueous phase containing aqueous ammoniated soaps and gums. The ammonia is recovered as before and the proportion of gums to fatty acids in the product may be varied by blending the oils treated or by varying the quantity of ammonia added. The mixed gums and fatty acids may be fractionated into a predominantly fatty acid fraction and a predominantly gum fraction by using water to hydrate the gums and separating, or by using solvents for the fatty acids. The oils may be purified in two stages comprising degumming by ammonia in the first-stage and removal of fatty acids in the second-stage by ammonia or other alkali. The gums or gum soap stock material may be de-oiled in an extractor with an oil solvent immiscible with water such as a hydrocarbon or chlorinated hydrocarbon, e.g. propane. The gums may first be precipitated with water from the oils and then treated with ammonia before further processing. The purifying process may be applied directly to the miscella obtained in the solvent extraction of oil from seeds.