Evaluation of Mass Transfer Properties in Convective Drying of Kiwi and Eggplant

The present work aimed at studying the mass transfer properties of two plant foods, kiwi (a fruit) and eggplant (a vegetable). For this convective drying experiments were conducted at different temperatures (from 50 to 80 ºC) and an air flow rate of 0.5 m/s, using slices with 6 mm thickness for both products. For the mathematical modelling two different methods were used, one based on the thin layer model and the other based on the Fick’s second law of diffusion. The results obtained allowed concluding that different methodologies allowed to obtain different values of the mass transfer properties, so care must be taken when choosing an appropriate calculation method. Regarding the values of diffusivity and mass transfer coefficient, in all cases they were found to increase with increasing operating temperature. Both the activation energy and the activation energy for convective mass transfer were similar for kiwi and for eggplant, indicating that both foods behave in a very similar way when exposed to the drying conditions tested.