Effect of Slice Thickness and Mathematical Modeling on the Thin Layer Drying Kinetics of Ginger Slices through Convective Drying

Abstract

In this study, thin-layer drying experiments were conducted on ginger (officinale Roscoe) slices at 30 mm and 40 mm thicknesses using a laboratory-scale convective hot-air dryer at temperatures of 50°C, 60°C, and 70°C with an air velocity of 1.5 m/s. Drying behavior was characterized by five mathematical models: Newton, Page, Modified Page, Henderson and Pabis, and Midilli-Kucuk. Model fitting was performed using nonlinear regression analysis. Statistical criteria, including chi-square (χ²), Root Mean Square Error (RMSE), and Coefficient of Determination (R²), were used to select the best-fit model. Among the five models, Midilli-Kucuk provided the best description of thin-layer drying behavior for both slice thicknesses across all drying temperatures, achieving the highest R² of 0.9989 and the lowest RMSE of 0.00934 at 70°C for 30 mm slices, and an R² of 0.9985 and an RMSE of 0.01087 for 40 mm slices. Effective moisture Diffusivity (Deff) ranged from 2.45 × 10⁻⁹ m²/s to 8.76 × 10⁻⁹ m²/s for 30 mm slices and from 1.98 × 10⁻⁹ m²/s to 7.34 × 10⁻⁹ m²/s for 40 mm slices. Activation energy was found to be 58.76 kJ/mol and 60.39 kJ/mol for 30 mm and 40 mm slices, respectively. The results provide valuable information for designing and optimizing industrial ginger drying systems.