Application of ultrasound treatment in cantaloupe infrared drying process: Effects on moisture migration and microstructure

Proper preservation and storage of fruits can prevent the wastage of these products and increase their availability outside the production season. With controlled and proper drying, nutrients and their color can be preserved. Cantaloupe slices were dried in a laboratory-scale infrared (IR) dryer with ultrasound (US) pretreatment. The influence of the US power and duration and different powers of IR dryers was analyzed. The drying processes were evaluated in terms of kinetic aspects (moisture ratio, time, and effective moisture diffusion (D-eff)), specific energy consumption (SEC), quality of the product (water activity (a(w)), color variation, rehydration ratio (RR)), bioactive properties (antioxidant activity, total phenol, and total flavonoid content), and vitamin C. The mathematical models were also fitted with the experimental data to assess the kinetics of cantaloupe dying. The results indicated that US pretreatment could facilitate the moisture release due to the cavitation phenomenon, hence declining the drying time (from 13.3% to 63.4%) and SEC (13.2%-67.4%) while raising the D-eff (2.83 x 10(-9 )to 1.99 x 10(-8) m(2)/s). The Midilli et al. model was selected to model the drying process due to its minimum error. After US drying, cantaloupe samples with higher color variation, RR, TPC, and vitamin C were determined. Considering more desirable results, the higher the US power, the better the AA, TFC, and a(w). At higher IR powers and longer US treatment, the quality of the samples showed a decline. The AA, TPC, TFC, and vitamin C showed an ascending trend followed by a decrease, raising the US time and IR power. The highest values were achieved for 30 min of US treatment and 500 W.