caustic chemical refining
alkali refining. in fat and oil processing: Alkali refining. Many of these can be removed by treating fats at 40Â° to 85Â° C (104Â° to 185Â° F) with an aqueous solution of caustic soda ( sodium hydroxide) or soda ash (sodium carbonate). The refining may be done in a tank (in which case it is called batch or tank refining) or in a continuous system.