Mechanical extraction of oil from Jatropha curcas L. kernel: Effect of processing parameters

Abstract

Mechanical extraction is considered to be the best option for oil expression of Jatropha curcas in rural areas. Lab scale hydraulic pressing experiments were conducted to investigate the effect of process parameters on oil recovery from Jatropha kernel. The ranges of pressing parameters investigated were: compression speed, 0.05–2.5MPa/s; applied pressure, 5–25MPa; moisture content, 1–6%; pressing temperature, 25–105°C; pressing time, 1–30min; shell removal, 0–100%; preheating time, 0–30min; and particle size, fine, coarse and whole kernel. Chemical analyses such as acid value, phosphorus content, oxidative stability index and water content were carried out to determine the quality of the oil. Moisture content was found to influence oil recovery at any applied pressure and pressure rates. Oil recovery increased to some extent with an increase in temperature or pressing time. The preferred moisture content was found to be about 4% (w.b.). The presence of Jatropha shell and size reduction of the kernel reduce oil recovery.The optimum oil recovery with respect to time of pressing and oil quality was obtained when Jatropha kernel was pressed at 15MPa, 90°C, 4% (w.b.) moisture content for 10min of pressing. The oil recovery obtained at these processing conditions was 86.1%.