GB642751A - Continuous bleaching of glyceride oils - Google Patents

Abstract

The customary continuous process of refining glyceride oils by alkali treatment, centrifuging, washing, drying and bleaching with fuller's earth or other bleaching clay is modified by bleaching the water-washed oil in the undried state and subsequently removing the moisture either from the oil-earth mixture prior to filtering, or from the filtered oil, by vacuum drying. More effective decolouration is thereby secured. According to an example, alkali-refined cottonseed oil issuing at about 130 DEG F. from the foots removing centrifuges is agitated for a short time in a closed chamber with 15 per cent of water and the mixture fed through another centrifuge to remove the aqueous phase containing dissolved soap and other impurities. The wet oil is then continuously mixed with a slurry of bleaching clay and previously-refined oil, vigorously agitated and heated to 175 DEG F. The wet oil-earth mixture passes to a flash tank or drying chamber under reduced pressure where the water vapour is drawn off, and finally passes to a rotary or other filter for removal of the bleaching earth. The heating of the wet oil prior to flash drying may be done before the addition of the bleaching clay, and the filtration of the bleached oil may be done before the flash-drying step. The process is applicable to all alkali-refined glyceride fats including lard, tallow, palm oil, coconut oil, cottonseed oil, peanut oil, soybean oil, whale oil, herring oil and sardine oil.