The influence of types and moisture contents of coffee beans (Coffea sp) on sphericity and geometric means diameter

Moisture content and particle dimension of coffee beans are the two important characteristics which often needed in many postharvest handling processes. This research was intended to investigate the effect of types and moisture contents on the changes of sphericity and geometric mean diameter of coffee beans. Three different types of coffee beans namely arabica, robusta, and liberica in three moisture contents of 9, 14, and 19 (w.b) were investigated in factorial design 3 x 3 with five replications. The dimensions of coffee bean were determined using ImageJ process and the values of sphericity and geometric mean diameter were then calculated. It was found that bean types, moisture contents, and the interaction between them were strongly affected the dimensions, sphericity, and geometric mean diameters of coffee beans (p<0.05). Robusta was found to have biggest sphericity and geometric mean diameter. As the moisture contents increased, it tends to produce higher geometric mean diameter, but this not applied to sphericity. The relationship between moisture content and sphericity could be expressed as polynomial of degree 2 equations, while geometric mean diameter can be correlated in linear regression equations for all types of coffee beans in this research.