Drying characteristics of eggplant (Solanum melongena L.) slices under microwave-convective drying

Abstract

A laboratory scale microwave-convection dryer was used to dry the eggplant fruit, applying microwave power in the range of 270–630 W, air temperature in the range of 40–70°C and air velocity in the range of 0.5–1.7 m/s. Six mathematical models were used to predict the moisture ratio of eggplant fruit slices in thin layer drying. The results showed that the Midilli et al. model had supremacy in prediction of turnip slice drying behavior. Minimum and maximum values of effective moisture diffusivity (D_eff) were 1.52 × 10^–9 and 3.39 × 10^–9 m²/s, respectively. Activation energy values of eggplant slices were found between 13.33 and 17.81 kJ/mol for 40°C to 70°C, respectively. The specific energy consumption for drying eggplant slices was calculated at the boundary of 86.47 and 194.37 MJ/kg. Furthermore, in the present study, the application of Artificial Neural Network (ANN) for predicting the drying rate and moisture ratio was investigated. Microwave power, drying air temperature, air velocity and drying time were considered as input parameters for the model.