Objective: To study the effect of slice thickness on drying process of Polygonum multiflorum root tuber.
Methods: The root tuber of Polygonum multiflorum was sliced with thickness of 2, 5 and 8 mm. Drying experiments were conducted at temperatures of 45, 55, 65 and 75 degrees C. The experimental data were fitted to ten thin-layer drying models to select a suitable model for describing the drying characteristic of Polygonum multiflorum root tuber. Based on thin-layer drying theory, the kinetics parameters of drying process were calculated.
Results: The drying processes of Polygonum multiflorum root tuber were consisted of two regions, 1st and 2nd falling rate periods when the slice thickness was thick or the drying temperature was high. Aghbashlo model was the best one to describe its drying behavior. The variation of thickness had significant effect on effective moisture diffusivity (D), but had little effect on activation energy E(a).
Conclusion: Thin-layer drying theory can be an effective tool for the study of drying behavior of Polygonum multiflorum root tuber. The result provides experimental basis for the quality control of Polygonum multiflorum root tuber drying process.