Enhancing experimentation and modeling of the impact of coffee particle size on the dynamic process of espresso extraction

Espresso extraction is a complex process governed by interconnected physical phenomena, where coff ee particle size plays a critical role. This dissertation systematically investigates how variations in particle size affect the hydrodynamics and mass transfer processes within the packed coff ee bed, using controlled experiments and mechanistic modeling. Key fi ndings reveal that particle size distribution infl uences bed compression, permeability, and extraction kinetics of key marker components. A series of mathematical models were developed and validated to describe diffusion– convection interactions, off ering predictive insights for optimizing espresso quality and enabling consistent performance in fully automated coff ee machines.