Statistical Analysis on the Geometric, Physical and Mechanical Properties of Dried Robusta Coffee Cherry Resulting from Natural System Processing

Abstract

The study conducted to evaluate the in-between correlation parameters of size, shape, physical and mechanical properties to provide information of physical and mechanical properties of the dried Robusta coffee cherry in relation with the development of coffee processing equipment. The physical and mechanical properties of the dried cherry were measured. The relationship in-between the physical and mechanical properties was analyzed using the stepwise regression analysis. The results of the study showed that polar diameter, equatorial diameter, thickness, geometrical diameter, arithmetic diameter, and surface area were dependent on volume with the correlation coefficient of 0.738, 0,761, 0.775, 0.994, 0.999 and 0.999 respectively. The sphericity was dependent on bulk density with a correlation coefficient of 0.437. The shape index, cross-sectional area and frontal surface area were dependent on particle density with the correlation coefficient of 0.959, 1.00 and 0.967 respectively. The correlation coefficient of the relationship between static friction and angle of repose on acrylic, stainless steel, and plywood were 0.772, 0.700, 1.000 and 0.930 respectively; otherwise, there was no correlation between the static friction and the filling angle of repose. The hardness of the dried cherry had a weak correlation with the fracturability.