Kinetics of drying and physical expansion of organic coffee beans during roasting: Mathematical modeling
DOI:
https://doi.org/10.25186/.v21i.2504Abstract
Coffee roasting is a crucial step in coffee processing, as the beans undergo important chemical and physical transformations that are directly related to the quality of the beverage. Many studies report on kinetics and mathematical modeling of different types of coffee bean drying, but it is necessary to understand the behavior of beans during the roasting process. This study sought to evaluate and model the behavior of the physical properties of organic coffee beans during the roasting process, focusing on volumetric and surface expansion and drying kinetics, in order to propose mathematical expressions applicable to mass and energy balances in the roasting process. The moisture content, water activity, specific mass, and dimensions of the beans were determined at different points during the roasting process. The experimental data were adjusted using mathematical expansion and drying models. The results indicated a progressive reduction in moisture content and in water activity from, contributing to the efficiency of thermal drying and the stability
of the final product. In addition, an increase in volumetric and surface expansion was observed, followed by a reduction in the specific mass of the beans. Overall, the models developed and validated (R2 > 0.90, P < 10%, SE < 1%, and residues with random behavior) proved to be effective tools for simulating and predicting the physical transformations that occur during the coffee bean roasting process. These models also help to elucidate the dynamics of the roasting process, enabling their application for optimizing and controlling the coffee roasting process.
Key words: Coffea arabica; Campos-Copace model; Nelder-Mead simplex algorithm; Typica variety.
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