Some Physical and Mechanical Properties of Pili (Canarium ovatum Engl. cv. Katutubo) Nut as a Function of Nut Moisture Content
The physical and mechanical properties of pili (Canarium ovatum Engl. cv. Katutubo) nut were determined as a function of nut moisture content in the range of 10.72–24.97% wet basis (wb). The force, deformation and specific deformation required to initiate shell fracture were determined by compression at transverse and longitudinal loading orientations using a universal testing machine (UTM). The physical dimensions of the nuts and shell thickness were not significantly (p < 0.05) affected by moisture content while width, height, geometric mean diameter and weights varied directly with nut moisture content. The force required to initiate shell fracture generally decreased with an increase in nut moisture content. The deformation and specific deformation required for fracture did not differ significantly among moisture content levels under traverse and longitudinal loading. At all moisture content levels, longitudinal compression required significantly higher force (2.66–3.15 kN), deformation (8.37–8.57 mm) and specific deformation (0.14 mm mm-1) for shell fracture compared with transverse compression (1.48–1.60 kN, 1.02–1.08 mm, 0.05 mm mm-1, respectively). Longitudinal compression, regardless of nut moisture content level, readily freed the kernel from the shell and yielded the highest whole kernel recovery (97.8%).
Key Words: Canarium ovatum Engl., compressive failure characteristics, mechanical properties, physical properties, pili nut, pili nut sheller
Abbreviations: MCwb – moisture content wet basis, UTM – Universal Testing Machine