Effect of sonication and osmotic dehydration applications on the hot air drying kinetics and quality of persimmon

Abstract

In this research, the effects of ultrasound pretreatment and osmotic dehydration applications on the hot air-drying behavior and quality of persimmon were investigated. Before drying persimmon in a tray dryer (60 °C, 1.5 m/s) ultrasound conducted in distilled water at 35 kHz for (10, 20, 30 min) and osmotic dehydration by sucrose solution at 100 rpm with 45 and 70°Brix were applied. All the groups were osmotically dehydrated after the ultrasound treatment and compared with the untreated group (not US pretreated) in terms of water loss, solid gain, weight reduction, and drying rate. The water loss, the solid gain, and the weight reduction increased with the increase of ultrasound treatment times. The results showed that the ultrasound pretreated (30 min) and osmotic dehydrated samples dried faster than untreated samples, and drying time decreased significantly by 46%. The drying rates (32.76%) and the effective diffusivities (45.65%) increased with the increase in ultrasound treatment times. There are no significant changes in the total phenolic content, and bulk density following ultrasound applications, whereas, it was determined that the color, and rehydration rate values changed statistically significant.