Determination and modeling of physical and aerodynamic properties of coffee beans ( Coffea arabica ) during the drying process

Abstract

The objective of this study was to determine and model the variation in the physical and aerodynamic properties of Arabica coffee beans during the drying process. The main physical properties (unit specific mass, sphericity, circularity, geometric diameter, projected area, volume, and volumetric contraction) and aerodynamic properties (terminal velocity and drag coefficient, actual and theoretical) were determined under different moisture content levels. It was found that the reduction in moisture content during drying resulted in major changes in the physical and aerodynamic properties of the coffee. Among the most significant changes, we can mention the 32% reduction in unit-specific mass and a 20% volumetric contraction. In addition, a 28% reduction in terminal velocity was observed, indicating that coffee beans can be separated by gravimetric methods at different moisture content levels. The new method, used to evaluate the theoretical aerodynamic properties, was satisfactory, presenting results similar to the experimental ones. Novelty impact statement This article is one of the only ones to provide a complete modeling and analysis of the physical and aerodynamic properties of coffee beans. A new model for obtaining theoretical aerodynamic properties was used in this study, which considers the sphericity of the product. The results found are of great interest because it allows from the creation and design of new equipment to various types of studies and numerical approaches.