Palm Oil Quality during Refining
Crude palm oil is refined to clean up the oil for edible purposes as well as for aesthetic acceptance by consumers who require a bland and light colored oil. Palm oil can be refined either by the chemical or physical refining process. The difference between the two processes is that the acid neutralization step is omitted in the physical refining process as compared to the chemical refining process. The free fatty acids are removed by the deodorization step in the physical refining process. Chemical refining is carried out at a lower temperature than the physical refining process and the residence time is also shorter. This would imply that there is a larger destruction of tocopherols and tocotrienols in the latter process. It also has a bigger chance of oxidative damage should there be an air leakage during the process. The higher processing temperature would lower the storage stability of the oil (Gapor & Berger, 1982; Loncin & Jacobsberg, 1963). In physical refining, it is important to eliminate phosphorus as much as possible during degumming and to prevent phosphoric acid slip-through, as this would affect the efficiency of heat bleaching later on in the process. Time-temperature effect is stronger in physical refining, as evidenced by the higher temperature used in the process and the longer residence time.