The physical properties of agricultural materials are functional in solving many glitches associated with machine design during handling and mechanical processing. Physical properties of five groundnut varieties (“Obolo”, “Yenyawoso”, “CRI Nkatie”, “Agbeyeyie” and “Pion”) and their relations to the design of food processing equipment were studied. Obolo variety recorded the maximum axial dimensions, 1000 mass grain, angle of repose, unit volume, and porosity. However, the values of bulk and true densities for Obolo variety were minimal compared with the other four varieties. Data for the angle of repose for the groundnut varieties were 17.74° (Yenyawoso), 18.02° (Pion), 18.73° (Agbeyeyie), 18.71° (Cri-Nkatie), and 18.89° (Obolo). The porosity of the kernels ranged from 21.97 to 24.54%. The mean greatest porosity was found in Obolo (24.54%), followed by Yenyawoso (24.38%), while Agbeyeyie recorded the least mean porosity of 21.97%. The coefficient of friction was greater for the galvanized steel surface than the other experimental surfaces for all the groundnut varieties studied. Analysis of variance (ANOVA) revealed varietal differences among some means of the physical attributes at p < 0.05. Except for the angle of repose, the geometric, gravimetric and frictional properties showed some significant differences at p < 0.05. Obolo variety was statistically different compared with the other four varieties for all the parameters studied. In selecting or designing equipment for processing, Obolo variety will require separate equipment different from that of the other four varieties. Additionally, the study provides pertinent data for use in the selection and designing of machines for processing groundnut kernels.
Key words: Postharvest processing equipment, geometric mean diameter, bulk density, frictional properties, groundnut kernels, angle of repose.