Drying behavior and thermodynamic properties of cashew nut almonds in thin layers: A mathematical modeling approach

Innovation in the drying process during the roasting of cashew nut almonds has the potential to significantly improve product quality. This study aimed to investigate the drying kinetics of the almond, comparing the experimental data with the mathematical models of Fick, Page, Cavalcanti Mata, and Henderson and Pabis. The research was conducted at the Laboratory of Physical Measurements and Drying of the Academic Unit of Food Engineering at the Federal University of Campina Grande. For drying, equipment with high air velocity and precise temperature control was used, operating at 120, 140, 160, and 180 °C, with an air velocity of 3 m s⁻¹. Based on the drying kinetics parameters, the activation energy for each mathematical model was determined, which indicates the energy required to break the bonds that maintain water in the product. The thermodynamic properties of the process were also determined, which are essential to help understand the drying behavior of the fruit, optimize energy efficiency and the quality of the final product. The Fick model, using six terms in the series and considering the cylindrical shape of the almond, along with the other models analyzed, showed a good fit for the experimental data, as evidenced by the R² values obtained. For the Fick model, the R² values varied between 0.9675 and 0.9738, for the Page model, between 0.9809 and 0.9954, for the Cavalcanti Mata model, between 0.9921 and 0.9973 and for the Henderson and Pabis model, between 0.9906 and 0.9976, for the temperatures studied.