Influence of infrared intensity and air temperature on energy consumption and physical quality of dried apple using hybrid dryer

Abstract

Apple slices were dried in a hybrid infrared-convective dryer. An experimental design was applied to analyse drying kinetics due to the effect of infrared intensity and air temperature. Apple slices that were either 2 mm thick were dried by the infrared intensity of 0.15, 0.2 and 0.3 W/cm2 with a convective air temperature of 30, 40 and 50 °C. The rate of drying increased and the drying period reduced with increasing infrared intensity. The air temperature was increased from 30 to 50 °C, drying time decreased by 84.62 and 192.31%, respectively. The lowest SEC was recorded at 4.32 MJ/kg at an air temperature of 50 °C and IR intensity of 0.30 W/cm2. The radiation intensity increasing 0.15–0.30 W/cm2 while holding the temperature at 30 °C affected the shrinkage ratio to reduction from a high of 0.25 to a low of 0.2 and the rehydration ratio increased from 3.2 to 3.8. Various drying models were compared and the Midilli et al. equation was established to be the best fit to the experimental data when compared to the other models.

Keywords

• Hybrid
• Quality
• Energy
• Drying kinetics
• Apple