**5.9 Refining**

Refining of crude palm oil (CPO) is carried out for removing impurities, free fatty acids, color, and odor. This is achieved through 2 routes, chemical and physical refining.

## **5.10 Chemical refining**

Major unit operations involved are degumming, neutralization and soap stock preparation, bleaching and filterations, deodourisation, and polishing.

#### **5.11 Degumming**

The precipitation process in which the impurities such as phosphates, protein fragments, and mucilaginous substances are removed. Degummed oil is treated with a calculated amount of caustic soda to remove free fatty acids in the form of soap. The soap water was separated by centrifugation, and the neutral oil was washed out of the alkali and soap using hot water at a temperature of 90°C, then by vacuum drying.

#### **5.12 Bleaching**

It is done to obtain palm oil with a lighter color and to remove traces of soap. Depending upon the crude palm oil 1–3% of bleaching earth at a temperature ranging from 100 to 150°C under vacuum for 15–30 minutes is employed.
