Drying was performed with untreated melon and with samples obtained under optimized conditions of pretreatment using a convective dryer (Sulab, Brazil) at 60 °C and constant air velocity of 2.0 m/s. The dryer system was described by Azoubel et al. (2010).
For each experiment, nine melons slices were spread on the drying tray (for sensorial analysis it was twelve slices). During processing, moisture contents of melon samples were determined by removing the tray from the dryer every 15 min. Then, it was rapidly weighted on a digital balance near the dryer and placed back into the equipment. Drying was completed when the dynamic equilibrium between the sample moisture content and drying air humidity was reached, when there was no significant change in the weight of the sample (105 min for the untreated sample and for the sample pretreated in sucrose solution and vacuum for 10 min; 75 min for the sample pretreated in distilled water using ultrasound for 10 min; 90 min for the sample pretreated in distilled water using ultrasound and vacuum).