Comparison of Bath and Probe Sonication for Osmotic Dehydration of Peach Slices: Study on the Qualitative and Nutritional Properties

Ultrasound-osmotic dehydration as a pretreatment prior to drying can reduce the cost and processing time while increasing drying efficiency. This study evaluated the effectiveness of bath and probe ultrasound-assisted osmotic dehydration, as a pretreatment of the drying process in an oven, on the qualitative characteristics of peach slices. Different conditions of pretreatment such as type of ultrasound (bath, probe), ultrasound temperature (25, 45 °C), ultrasound time (15, 30 minutes) and probe ultrasound intensity (75, 100 %) were investigated on the efficiency of osmotic dehydration, water activity, shrinkage, texture, rehydration, color, and vitamin C. The highest efficiency of osmotic dehydration was for the pretreated sample by probe ultrasound (45 °C-15'-100%). Osmotic-ultrasound pretreatment caused tissue stiffness, reducing in shrinkage and rehydration in the sample due to absorption of solids. Probe ultrasound, especially at high temperatures, compared with the bath ultrasound increased the total color difference and decreased the amount of vitamin C in the samples. Finally, in terms of overall acceptance, the samples under the bath ultrasound (25 °C-30 ') and under the probe ultrasound (25 °C-15'-100%) had the highest score.