Mathematical Modeling of Drying Kinetic of Strawberry Slice in Microwave-Hot Air Dryer

In this study, a hot air- microwave dryer equipped to imaging system was used for modeling of drying kinetics of strawberry slice. The experiments were conducted at three levels of hot air temperature of 50, 60, and 70  C with 0.5 m/s air velocity as well as three levels of microwave power density of 2.7, 3.5 and 5 W/g with 40 C air temperature. In order to estimate the drying curve, seven different thin layer mathematical drying models were fitted to experimental data and according to the obtained results, Page’s model could satisfactorily describe the drying curve with highest R2 value (0.9945-0.9987) and lowest RMSE (0.0097-0.0213) of microwave data and Logarithmic model could describe the drying curve with highest R2 value (0.9945-0.9987) and lowest RMSE (0.0097-0.0213) of hot air drying data. Also ∆E color kinetic demonstrated that highest color changes were happened in the initial drying stage and remained constant in the other drying stage in microwave and finally the ∆E value changed in any power density near 10. But in hot air drying the color changes occurred progressively during drying process and reached upper than 15.