Effects of Particle Size on Palm Kernel Oil Yield under Uniaxial Loading

Abstract

The effects of particle size on oil yield expelled from palm kernel under uniaxial loading were studied. Palm kernel (Dura Variety) was obtained and dried to 4.5% moisture content. The palm kernels were crushed, the crushed meal was further size reduced to obtain fine samples. The crushed samples were classified into fine and coarse particle sizes using a set of laboratory Endocotts Test Sieves and Shaker. A laboratory mechanical oil expeller with a temperature controller and a force measuring device were used to express oil from the palm kernel under uniaxial compression using a hydraulic press. The effects of coarse and fine particle size on oil yield were studied at heating temperatures of 70, 90, 110 and 130°C and applied pressures of 6.0, 9.0, 12.0 and 15.0 MPA, respectively. The results obtained were subjected to statistical analysis using Analysis of Variance (ANOVA) and T-test. Particle size had significant effects on oil yield at 1% level of significance. The study revealed that oil yield from fine particle size are higher and significantly different from that obtained from the coarse particle size at all operative parameters (temperature and pressure) investigated. The highest oil yield of 22.90% was obtained with fine particle samples at a heating temperature of 70°C and applied pressure of 15.0 MPA. It is then concluded that, in order to maximize oil yield during mechanical expression of oil from palm kernel under uniaxial loading, the palm kernel size should be reduced to fine particles.

Keywords: Oil yield, uniaxial compression, particle size, palm kernel