GB596871A - Process of refining glyceride oils and fats - Google Patents

Abstract

A crude vegetable glyceride oil or fat containing as impurities free fatty acids, non-fatty colloidal matter, and colouring matter, is refined by neutralising it with dilute aqueous alcoholic caustic alkali at 60 DEG -150 DEG F. in quantity just sufficient to saponify the free fatty acids and to solvate the non-fatty impurities and a substantial part of the colouring matter but insufficient to salt out the saponified products, thereby avoiding emulsification of the neutral oil and conditioning the mixture to have liquid foots, then separating the liquid foots from the neutralised oil, and washing and drying the oil. Preferably, after the treatment with the aqueous alcoholic caustic soda or potash, the oil is treated with a small quantity of aqueous caustic soda or potash to remove further amounts of colouring matter. The process is particularly applicable to the refining of crude cottonseed oil. The alcoholic caustic soda may contain 8-10 per cent. of ethyl alcohol and 2-5 per cent. of caustic soda and the amount may be such that the excess of caustic soda is equivalent to 0.2-1 per cent. of free fatty acid. The oil may be refined in a conical bottomed kettle provided with heating coils and variable speed agitation, or in a centrifugal apparatus. The caustic soda solution may be sprayed into the oil during vigorous agitation. Mixing may be continued for 20 minutes or more after which the oil is allowed to settle and the foots liquid is drawn off. The oil may then be treated with aqueous caustic soda solution of 12-20 DEG B<\>ae in an amount equivalent to 0.5-1 per cent. of free fatty acid. This treatment may be effected at 130 DEG -180 DEG F. The oil may then be washed with water at 190 DEG -200 DEG F. In an example, crude cottonseed oil containing 1-2 per cent. of free fatty acid is refined by treatment with 7-10 per cent. of an alcoholic caustic soda solution containing 0.7-1.0 per cent. of alcohol and excess of caustic soda equivalent to 0.2-1 per cent. of free fatty acid.