Mathematical Modeling of Moisture Diffusivity and Mass Transfer During Drying of Coffea arabica L. var. Catimor

Fernandez-Rosillo F.; Velayarce-Vallejos F.; Fernández-Rosillo L.; Sánchez-Goycochea N.A.; Cabrejos-Barrios E.M.; Hernández-Martínez E.; Damián-Sandoval J.C.; Chávez S.G.; Valle-Epquín M.G.; Balcázar-Zumaeta C.R. · Agriculture (Switzerland) (2026) · DOI: 10.3390/agriculture16131402

Resumen

Understanding mass transfer mechanisms during coffee drying is essential for optimizing postharvest processing conditions. This study aimed to estimate the effective moisture diffusivity coefficient ((Formula presented.)) and convective mass transfer coefficient ((Formula presented.)) of Coffea arabica L. var. Catimor through mathematical modeling. Drying experiments were conducted in an automated convection dryer (CE 130) at four constant temperatures (40, 50, 60, and 70 °C) and an air velocity of 1.5 m/s. Drying time, equilibrium moisture content ((Formula presented.)), and critical moisture content ((Formula presented.)) were determined. A MATLAB based algorithm was developed to solve Fick’s second law and estimate (Formula presented.) and (Formula presented.) during coffee drying. An Arrhenius-type model was further applied to describe the temperature dependence of both coefficients. Although the model captured the general increasing trend with temperature, only moderate coefficients of determination were obtained (R2 = 0.63 for (Formula presented.) and R2 = 0.74 for (Formula presented.)). Drying times were 26.5, 17.5, 16.5, and 13.5 h at 40, 50, 60, and 70 °C, respectively. (Formula presented.) ranged from 11.30% to 11.76% (wet basis), while (Formula presented.) remained close to 46% (wet basis) at all temperatures. (Formula presented.) ranged from (Formula presented.), whereas (Formula presented.) ranged from 1 (Formula presented.). Both coefficients increased with temperature, indicating enhanced internal diffusion and external mass transfer. These findings provide useful engineering parameters for modeling, design, and optimization of industrial coffee drying processes.

Instituciones: Universidad Tecnológica del Perú; Universidad Nacional Toribio Rodríguez de Mendoza de Amazonas; Universidad Nacional de Jaén