O.K. Owolarafe

Comparative evaluation of the digester–screw press and a hand-operated hydraulic press for palm fruit processing

Abstract In order to demonstrate the strength and possible weaknesses of the digester–screw press (DSP) system for small-scale oil palm fruit processing, a comparison was made of its performance and that of the erstwhile hand-operated hydraulic extraction system. Indices of evaluation include oil yield and quality, and operational economics. The results indicate that the throughput of the DSP system was four folds of that of the hydraulic system, whilst also operating at higher oil extraction efficiency (89.1%). There was no significant difference between the quality of the palm oil obtained from the two systems. However, the economic analysis of the systems indicates that at throughput of 0.75 t/h and above, the DSP system was more economical than the hydraulic system in terms of equipment, labour, material and floor space requirement and revenue accruing from the processing operation.

Development of a Permeability Model for Palm Fruit Cake

Investigation was carried out on the effect of processing conditions such as temperature, pressure and porosity on permeability of palm fruit cake. It was observed that increasing the temperature of the crude palm oil from 30 to 75°C, pressure from 2.88 to 3.82 kPa and porosity from 9.2 to 27.3% increases the permeability of the palm fruit cake. The statistical analysis of the effects of the processing factors on permeability indicates that temperature and porosity are significant at 99.99% while pressure was significant at 95%. A permeability model applicable to the practical palm oil expression was also developed in the study.