The influence of pressing speed on energy demand and percentage oil yield of Jatropha
curcas L. bulk seeds was examined in compression loading test using Universal Testing
Machine and vessel diameter of 60 mm. Maximum force of 100 kN and speed between 1
and 50 mm min1 were applied on jatropha bulk seeds of initial moisture content 8.61% ±
1.14% (w. b.) at pressing height of 60 mm. The mechanical behaviour and deformation
characteristic curves of jatropha bulk seeds were also assessed in relation to speed. Based
on the statistical analysis of results, deformation energy decreased significantly (p < 0.05)
with increasing speed from 0.43 ± 0.01 to 0.41 ± 0.01 kJ and oil yield from 19.05 ± 1.16 to
11.66 ± 0.82 (%) while slight decreases in maximum deformation from 45.02 ± 0.29 to
43.38 ± 2.63 (mm) were not statistically significant (p > 0.05). In contrast, oil point force
increased with increasing compression speed from 17.03 ± 2.33 to 59.27 ± 30.81 kN, oil point
deformation from 38.22 ± 0.49 to 41.99 ± 1.40 mm and oil point energy from 0.15 ± 0.01 to
0.31 ± 0.09 kJ, all significant at p < 0.05. The dependency between force and deformation
curves of jatropha bulk seeds as function of speed did not exhibit any serration effect. The
present study provides preliminary result that can support the incorporation of the speed
variable into the already published tangent curve mathematical model, which can represent
mechanical and deformation behaviour of bulk oilseeds under compression loading.