Refining of Edible Oils

Edible oils obtained from coconut, corn, cottonseed, olive, palm, peanut, soybean and sunflower etc. contain gums and other impurities which are removed by degumming, neutralizing and bleaching processes. The wide range of oils processed by these methods leads to considerable variations in process requirements: * Oils which tend to emulsify may be held in a vessel after mixing with the reagent to allow the emulsion to break before passing to the separator. * In the degumming process the typical acid addition is 0.1 - 1%. Phosphoric acid is most commonly used, although citric acid is suitable for some oils. * Process temperature is typically in the range of 120 - 160°F (50-70°C). * Neutralization process temperature may be higher, up to 200°F (95°C) * The strength of the sodium hydroxide solution varies according to the acid content and oil type. * During bleaching, a filter aid such as diatomaceous earth may be added to prevent the finer clay particles from blinding the filter medium