The study was conducted on an experimental FIR(far-infrared)-assistrd freeze dryer to determine the drying characteristics of sweet potato during feeze-drying. Drying parameters of four thin-layer drying models(exponential model, Page model, diffusion model, and approximation of the diffusion model) were evaluated to decide the optimum drying model. Tests were conducted using a three-level, three-factor(drying temperature, distance between sample and FIR heater, and sample thickness) experimental design, and second order polynomial analyses were performed to relate the drying parameters of those four thin-layer drying models.The performance of these thin-layer drying models was evaluated by comparing the coefficient of correlation(R2), the sum of squares(lack-of-fit), and the RMSE amongst four models. Deying parameter K of the page model gave the best results in describing freeze-drying with FIR of sweet potato. Verification tests indicated that thoge generated second order polynomial models were acceptable, and validation proved the results to be adequate.
