Suitability of thin layer models for infrared-hot air-drying of onion slices

Onion slices were dried under different processing conditions applying infrared radiation assisted by hot air. Drying temperature, slice thickness, inlet air temperature and air velocity were varied to study the drying behavior. Thin layer models such as Page, modified Page, Fick's and Exponential models, which are used to describe the drying kinetics of food materials, were tested for the combination mode drying. The linear plots for Page and modified Page models gave a better fit (R²=0.980-0.995) over the other two models (R²=0.767-0.933). A combined regression equation developed to predict the drying parameters (k and n) for all the four models gave a fairly good fit (R²=0.852-0.989). The modified Page model gave better predictions for drying characteristics over the other models.