Energy demands for pressing Jatropha curcas L. seeds

Abstract

Experiments were carried out to determine required energy for pressing Jatropha curcas L. seeds (IPB2 variety from Indonesia), at three stages of fruits maturity, i.e. green (unripe), yellow (ripe) and brown (over-ripe), using two pressing techniques (cold 20 degrees C and hot 60 degrees C). Relationships between the pressing force and absolute seed deformation, the size of stress and relative seed deformation, and the seed modulus of elasticity in compression were calculated. Specific regions of pressing and adequate pressing force size interval were specified. The limit points for pressing any maturity stage of J. curcas L. seeds were defined: the lower limit of the relative deformation (lower oiliness point) epsilon(L) = epsilon(mezl) = 0.4, and the upper limit of the relative deformation (upper oiliness point) epsilon(U) = epsilon(mezll) = 0.8. The following equations were defined as being generally applicable for the pressing of seed mixtures. The relationship between pressing force value and absolute seed deformation was F(Delta L) = 155.tan(0.157.Delta L), where F (N) is the pressing force and Delta L (mm) is the deformation. The relationship between the compressive stress and relative deformation was sigma(epsilon) = 0.863.tan(1.571.epsilon), where sigma (MPa) is the compressive stress and epsilon (-) is relative deformation. The relationship between the modulus of elasticity in compression and relative deformation was E(epsilon) = 1.3558.[1 + (tan(1.571.epsilon))(2)], where E (MPa) is the modulus of elasticity in compression. The relationship between deformation volume energy and relative deformation was W(epsilon) = [0.275.ln[1 + (tan(1.571.epsilon))(2)]](epsilon 1)(epsilon 2), where W (J mm(-3)) is the deformation volume energy. (c) 2010 IAgrE. Published by Elsevier Ltd. All rights reserved.