Some physical properties and cracking energy of conophor nuts at different moisture content
 
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Department of Agricultural Engineering, Federal University of Technology P.M.B. 1526, Owerri, Imo State, Nigeria
 
Int. Agrophys. 1995, 9(2): 131–142
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ABSTRACT
Freshly harvested conophor fruits (Te-tracarpidium conophorwn) were processed traditionally and the nuts extracted. Physical measurements of axial and radial diameters, nut weight and volume were taken and used to compute the nut's density and sphericity. The energy to crack the nut and release the kernel was obtained using the 'nut cracking energy instrument* for different moisture contents. Visual observation was used to assess the cracking percentage of the nuts. Results show that the conophor nut (African walnut) has average sphericity of 0.91, radial diameter of 2.90 cm and an axial diameter of 3.19 cm. The density of the fresh nuts (68.8 % moisture content) was found to be about 0.877 g/cm3 while the nut thickness was 0.067 cm. Full cracking of nuts increased with decreasing moisture content and increased drop height. The cracking energy was influenced by nut mass and radial diameter as well as shell moisture content. The nut and kernel moisture content have high linear relationship with the shell moisture content. However, impinging velocity of about 4 m/s was adequate to sufficiently crack conophor nuts of not more than 30 % moisture content and release the kernel.
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