Aerobic Liquor Washing Improves the Quality of Crude Palm Oil by Reducing Free Fatty Acids and Chloride Contents

The presence of free fatty acids (FFA) and chloride contents in crude palm oil is not desirable because they have an impact on oil quality and food safety. This work presents a method to reduce these compounds by washing the crude palm oil (CPO) with treated aerobic liquor (AL). The effects of process parameters on the reduction of FFA and chloride in CPO and the resultant 3-monochloropropane-1,2 diol ester (3-MCPDE) formed after refining are investigated. The results show that the AL dosage, initial FFA content, mixing speed, and duration have significant influence on the reduction of FFA in the CPO. Meanwhile, the chloride content is reduced by approximately 50% regardless of the AL dosage used. Consequently, the 3-MCPDE content in the oil after refining is up to 53% lower than that of the refined oil produced from the untreated CPO. Furthermore, an oil recovery above 97% can be achieved after the AL-washing step. The implementation strategy of this method in the palm oil mills has also been proposed. In conclusion, an effective and sustainable method for in situ improvements of the quality and food safety of palm oil has been developed without the need for additional water or chemical. Practical Applications: Treated aerobic liquor can be used to wash the CPO in palm oil mill for in situ reductions of FFA and chloride contents in CPO to improve the oxidative stability of CPO. The lower content of chlorides in CPO could mitigate the formation of 3-MCPDE during refining, thus improving the food safety of palm oil. This method can readily be implemented by the industry and it is sustainable because it does not require the use of additional process water or chemical.