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Why are refined oils washed with water after alkali treatment?
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fat and oil processing
Butter.
After alkali treatment, refined oils are washed with water primarily to remove residual traces of alkali and soapstock.
During the alkali refining process, fats are treated with substances like sodium hydroxide or sodium carbonate to neutralize free fatty acids, which creates an emulsion of soaps and other impurities known as soapstock. Washing the oil with water ensures that these leftover chemical agents and soap residues are effectively eliminated, resulting in a neutral oil that is free of materials that might otherwise separate upon heating.1