Effect of Temperature on Drying Kinetics of Vegetable Seeds Thingujam

A study was conducted to investigate the effect of temperature on drying kinetics of onion, carrot and tomato seed. The seeds were dried at drying temperatures of 30°C, 35°C and 40°C in a laboratory hot-air oven dryer. Drying rate was faster at higher temperature (40°C) than at lower temperatures. Drying of the seeds occurred in falling rate periods of drying. Drying data were fitted into Newton, Page, Modified Page, Henderson-Pabis, Logarithmic, two-term exponential, and Wang and Singh models. Based on highest R² and lowest χ2, RMSE and mean error values, Page model (R²>0.9) was found to be the best fit for drying of all selected seeds at the selected temperatures. However, two-term exponential model was the best fit for onion seed at 35°C and carrot seed at 30°C, and was comparable with Page model in the selected temperature range. Effective moisture diffusivity of onion, carrot and tomato seed ranged between 1.59 x 10⁻¹⁰ m².s⁻¹ and 3.18 x 10⁻¹⁰ m².s⁻¹, 3.55 x 10⁻¹⁰ m².s⁻¹ and 7.10 x 10⁻¹¹ m².s⁻¹, 2.65 x 10⁻¹⁰ m².s⁻¹ and 5.31 x 10⁻¹¹ m².s⁻¹, respectively, at above drying temperatures. Activation energies of onion, carrot, and tomato seed were 56.85 kJ.mol⁻¹, 60.69 kJ.mol⁻¹, and 61.44 kJ.mol⁻¹, respectively.