Mathematical Modeling of the Drying Process in the Thompson Seedless Grape Variety: Kinetic and Thermodynamic Parameters

The Thompson Seedless grape is a fruit of great economic importance, and its dehydration is a crucial technique for its preservation. Mathematical models are a fundamental tool to optimize the drying process and ensure the quality of the final product. Therefore, the main objective was to study the drying kinetics of the Thompson Seedless grape and evaluate the mathematical model that best fit the experimental curves in order to optimize the kinetic and thermodynamic parameters. For this purpose, grapes were dried in a tray dryer at 50°C, 60°C, and 70°C, and the moisture ratio (MR) was calculated. Additionally, 14 mathematical models were evaluated, and the goodness of fit was determined using statistical tests such as the sum of squared errors (SSE) and the mean squared error (MSE). The diffusion coefficient (D_eff), activation energy (E_a), and thermodynamic parameters were also calculated. The results showed that the dehydration rate increased significantly with temperature. The Midilli and Kucuk model was the one that showed the best fit to the drying curves. The effective diffusivity coefficient (D_eff) increased with temperature, while the activation energy (E_a) was high, indicating that the process is highly temperature-dependent. The thermodynamic parameters confirmed that the drying process is not spontaneous and that the Gibbs free energy (ΔG) is positive, which requires a continuous input of external energy.