ABSTRACT
Rubber seeds are a valuable source of oil and bio-based materials, but their high moisture content necessitates efficient drying techniques for long-term storage and processing. This study aimed to investigate the drying kinetics of whole and sliced rubber seeds at different temperatures (50, 60, 70, 80, and 90°C) and determine the best-fitting drying model. Additionally, the effective moisture diffusivity and activation energy were evaluated to understand the moisture transport mechanism during drying. Experiments were conducted using an oven dryer, where moisture loss was recorded at regular time intervals until equilibrium moisture content was reached. The drying data were fitted to five commonly used thin-layer drying models: Lewis, Page, Henderson & Pabis, Logarithmic, and Midilli et al. The best-fitting model was selected based on statistical parameters, including the coefficient of determination (R²), root mean square error (RMSE), and reduced chi-square (χ²). Effective moisture diffusivity was determined using Fick’s second law of diffusion, and activation energy was estimated using the Arrhenius equation. The results showed that drying temperature significantly influenced drying kinetics, with higher temperatures leading to faster moisture removal. Among the models evaluated, the Midilli et al. model provided the best fit, as indicated by its highest R² and lowest RMSE and χ² values across most temperatures. Effective moisture diffusivity increased with temperature, ranging from 2.62 × 10⁻¹⁰ to 7.08 × 10⁻¹⁰ m²/s for whole seeds and 0.85 × 10⁻¹⁰ to 3.85 × 10⁻¹⁰ m²/s for sliced seeds. The activation energy was 25.63 kJ/mol for whole samples and 38.59 kJ/mol for sliced samples, suggesting that sliced seeds required more energy for moisture diffusion
