Effect of Different Drying Conditions on the Mass Transfer Characteristics of Kiwi Slices

In this study, the influences of drying conditions on the mass transfer characteristics of kiwi slices are investigated using the analytical model proposed by Dincer and Dost. The experiments were conducted at temperature range of 50–80°C with 0.5 m s^-1 air velocity for convective drying and in the microwave power range of 200–500W for microwave drying as single layers with sliced thickness of 3, 6, and 9 mm. The results show that the mass transfer characteristics strongly depend on the drying conditions. Through the convective drying method, parameters including moisture diffusivity, mass transfer coefficient, Biot number, and drying time were varying from 0.16-1.45×10^-8 m² s^-1, 1.93-4.95×106^−7 m s^-1, 0.103-0.225, and 90-604 minutes, respectively. In comparison, for microwave drying, they were within the ranges of 0.66-25.60×10^-8 m² s^-1, 0.62-5.64×10^−5 m s^-1, 0.960-1.742, and 4-23.5 minutes, respectively. Results reveal that the activation energy for moisture diffusion is higher than that needed for the convective mass transfer process.