EFFECT OF ULTRASOUND ASSISTED OSMOTIC DEHYDRATION PRE-TREATMENT ON DRYING KINETICS AND SOME FUNCTIONAL PROPERTIES OF PUMPKIN (Cucurbita moschata)

Abstract

In this study, the effect of ultrasound assisted osmotic dehydration (US-OD) pretreatment on drying kinetics and some functional properties of pumpkin (Cucurbita moschata) were investigated. The samples were dehydrated by cavitation (45 kHz, 90 minutes) in an ultrasonic bath containing sugar solution with three different concentrations (12.5%, 25% and 50%) and then dried with oven at 60oC. With the US-OD process, the highest water loss and solid gain were detected in the sample dehydrated using osmotic solution with 50% concentration. Depending on the sugar solution concentration of the US-OD process, the drying time was shortened by approximately 180 min compared to the control sample. However, a decrease in the rehydration rate was observed depending on the sugar concentration of osmotic solution. The highest total phenolic content (120.08 mg GAE/100 g dry weight) and antioxidant capacity (38.21%) were determined in the sample dehydrated in osmotic solution with 50% concentration and dried. When the outputs obtained from the study were adapted to the mathematical models, it was concluded that the best describing model drying of the US-OD pre-treated pumpkin was the Page model.