GB920349A - Improvements in and relating to purification of fats - Google Patents

Abstract

<PICT:0920349/III/1> <PICT:0920349/III/2> Wet alkali-refined fat is further purified to remove alkali and soap residues by treatment with 0,015-0,05% by weight of the fat of a non-toxic fat-insoluble acid which has a dissociation constant greater than that of the fatty acids of the soap residues, the treatment being conducted under conditions of vacuum drying whereby a precipitate of salts forms in the fat, which precipitate is removed by filtration. The fat to be treated is suitably coconut or rape oil, and the non-toxic acid may be hydrochloric, lactic, tartaric, or acetic acid, but is generally citric acid. The reaction is preferably carried out at 80 DEG -95 DEG C., suitably in the presence of a reducing agent; as a reducing agent, hydrogen gas or, more usually, sodium bisulphite in an amount of 0,01-0,03% by weight of the fat may be used. The fat may be bleached with a bleaching earth simultaneously with or subsequently to the treatment with acid, and may also later be deodorized. Fig. 1 illustrates an embodiment for batch treatment. Fat is passed by line 2 to tank 1 maintained at low pressure through line 7. Citric acid from tank 6 and bleaching earth from tank 4 are added by lines 5 and 3 and the mixture agitated by agitator 8. On completion of the treatment, pump 10 passes the mixture through line 9 to filter 11, whence the fat passes to a deodorization treatment. Fig. 2 illustrates an embodiment for continuous treatment. Fat is passed to spraying device 22 situated in container 12 evacuated through line 21. The sprayed fat is collected in tray 13 and agitated by stirrer 19 with citric acid solution run in from tank 23. The mixture passes through outlet 16 to tray 14 which is also fitted with an agitator 20, and bleaching earth, either in powder form or as a suspension in oil, is run in from tank 25. After some 15 minutes, the mixture is passed through drain 17 to buffer tank 15, and thence by pump 18 through filter 28. Automatic programme apparatus 27 controls the operation of valves 24 and 26, and drains 16 and 17.