Modern processing of oil palm fruit bunches into edible oil is practiced using various methods, which may be grouped into four categories according to their throughput and degree of complexity. These are the traditional methods, small-scale mechanical units, medium-scale mills and large industrial mills.
Generally, processing units handling up to 2 tonnes of fresh fruit bunches (FFB) per hour are considered to be small-scale. Installations that process between 3 and 8 tonnes FFB per hour are termed medium-scale, while large-scale refers to mills that process more than 10 tonnes per hour.
Much has been written about traditional technologies and medium- and large-scale mills, but information on small-scale processing units is scarce. The historical reason for the ready availability of information on medium- to large-scale operations and machinery is that most development work was undertaken in Europe, based on the observation of the traditional methods practiced in West Africa.
Machinery manufacturing is a recent development in the West African sub-region, and until recently it has not been possible to develop the sophisticated machines required to improve on traditional methods. Machinery manufacture in Africa must be carefully considered if progress is to be made in joining the rest of the industrialised world. Even now it is difficult to manufacture and sell bolts and coiled springs in the Central and West African sub-region. However, the manufacture of machines and combining them in processing assemblies for small-scale rural industries is not within the scope of this publication. The main objective of this publication is to provide a detailed description of the various processes involved in small-scale palm oil processing, the type of machinery and equipment required, and their performance, energy and water consumption. The effect on the environment caused by waste and by-product uses is considered in Chapter 6.
At the outset it must be stated that small-scale palm oil processing in the sub-region has systematically acquired sophistication, efficiency and reliability. It is agreed that traditional methods of extracting palm oil were inefficient and tedious for making oil for sale.
Generally women in the villages are responsible for the processing and sale of farm produce. Small-scale agro-processing seems to hold the key to rural poverty reduction and the prolific oil palm tree provides the best raw material for starting rural industries.
Today small-scale processors who appreciate the value of using machines, are asking for them to be more sophisticated. Thus current demand for small-scale palm oil mills is shifting from simple stand-alone unit operational machines to a more integrated system which is easy to operate and maintain. Machinery manufacturers have responded with machines that combine several operations into one machine unit. The complete range of operational machines - covering bunch stripping, fruit sterilization, digestion, pressing, clarification, oil drying and storage have been developed for small-scale processing applications. The processors can change and/or combine equipment to suit their purchasing power.
In this publication the palm tree and its fruit are first considered; then the principles underlying palm oil extraction and preservation are examined. A general description of palm oil processing and the associated unit operations necessary to obtain the oil will follow. Once each step in the oil extraction process has been explained, it will be possible to apply the criteria for the selection of equipment required to meet the processors needs and investment potential.
A by-product of palm oil extraction is the palm nut which, when cracked, yields a kernel containing a completely different kind of oil which can be used as a valuable substitute for cocoa butter. Unfortunately not many palm oil processors include palm kernel extraction at the same location. It is more usual that a completely different group undertakes palm kernel extraction.
To explain why this occurs, a description is included of how palm kernel oil is extracted and the relevant machinery and equipment needed, is indicated.
Finally, the major machinery manufacturers and designers of equipment in Central and West Africa are presented, listing their main products, innovations and achievements. Photos have been included to illustrate what manufacturers are doing in this sector.
Palm oil and palm kernel processing involve many different procedures. Therefore, the ability to make machinery that can handle the many unit operations involved is indicative of a generalised ability to produce processing machines for other crops. Many machines developed for the palm industry can undertake the same functions for other crop applications with minor modifications. For instance, sterilizers are capable of cooking vegetables, cereals and grains as well as roots and tubers. The vertical digester may be modified to function as a mixer while the screw-presses and expellers can be used for extrusion and de-watering applications. Therefore, readers are urged to contact the manufacturers as to the application of their machinery in other industrial applications.