This section on general processing description is excerpted from the FAO Agricultural Services Bulletin 148 (FAO, 2002) supplemented by some additional information from other relevant sources.
Research and development work in many disciplines – biochemistry, chemical and mechanical engineering – and the establishment of plantations, which provided the opportunity for large-scale fully mechanised processing, resulted in the evolution of a sequence of processing steps designed to extract, from a harvested oil palm bunch, a high yield of a product of acceptable quality for the international edible oil trade. The oil extraction process, in summary, involves the harvesting of FFB from the plantations, sterilising and threshing of the FFB to free the palm fruit, crushing the fruit and pressing out the CPO. The crude oil is further treated to purify and dry it for eventual storage and export.
Large-scale plants, featuring all stages required to produce palm oil to international standards, are generally handling from 3 to 60 tonnes of FFB/hr. The large installations have mechanical handling systems (bucket and screw conveyers, pumps and pipelines) and operate continuously, depending on the availability of FFB. Boilers, fuelled by fibre and shell, produce superheated steam, used to generate electricity through turbine generators. The lower pressure steam from the turbine is used for heating purposes throughout the factory. Most processing operations are automatically controlled and routine sampling and analysis by process control laboratories ensure smooth, efficient operation. Although such large installations are capital intensive, extraction rates of 19-21% palm oil per bunch can be achieved from good quality such as Tenera variety.
Conversion of CPO to refined oil involves removal of the products of hydrolysis and oxidation, colour and flavour. After refining, the oil may be separated (fractionated) into liquid and solid phases by thermo-mechanical means (controlled cooling, crystallisation, and filtering), and the liquid fraction (olein) is used extensively as a liquid cooking oil in tropical climates, competing successfully with the more expensive groundnut, corn, and sunflower oils.
Extraction of oil from the palm kernels is generally separated from palm oil extraction, and often carried out in mills that process other oilseeds (such as groundnuts, rapeseed, cottonseed, shea nuts or copra). The stages in this process comprise grinding the kernels into small particles, heating (cooking), and extracting the oil using an oilseed expeller or petroleum-derived solvent. The oil then requires clarification in a filter press or by sedimentation. Extraction is a well- established industry, with large numbers of international manufacturers able to offer equipment that can process from 10 kg to several tonnes per hour.
Palm oil processors of all sizes go through these unit operational stages. They differ in the level of mechanisation of each unit operation and the interconnecting materials transfer mechanisms that make the system batch or continuous. The scale of operations differs at the level