A study of the shape and size of wet parchment coffee beans

Abstract

The growth of a coffee berry and the beans contained therein is the result of a highly complex physiological process carried on in the tree, several recognized shapes of beans emerging as a result of the various factors influencing the growth. In the present study, a quantitative definition has been provided to these shapes at the important wet parchment stage in terms of their length, width, depth and the areas of flat and transverse surfaces, the latter being obtained by a cross-sectioning of the bean. Both Arabica and Robusta varieties have been studied. Empirical equations for various been shapes have been proposed, based on a large number of measurements, to express the correlation between the three principal dimensions of a bean. Another set of suggested equations can be used to predict with reasonableaccuracy either of the two areas from a measurement of any one of these three dimensions. For both the areas, the relationship between the calculated (from a consideration of a truly elliptical shape) and the measured value have also been shown. Arabica and Robusta coffee are seen to have varying characteristics, the former being larger in size with a generally elongated shape longitudinally as well as laterally in comparison with the latter variety.