Optimization of ultrasound-assisted osmotic dehydration of pomegranate seeds (Punica granatum L.) using response surface methodology

peer reviewedThe main objective was to investigate the effect of ultrasound-assisted osmotic dehydration (UOD) pretreatment on the dehydration kinetics and the physicochemical properties of pomegranate seeds using a response surface methodology, in order to optimize the process. Quality attributes of seeds were estimated through the assessment of physical and thermal characteristics. Results showed a good correlation of experimental values with the model. The optimum conditions used for UOD and osmotic dehydration (OD) were found to be 240 min, 60°Brix, 41°C, and 240 min, 29°Brix, 50°C, respectively. UOD pretreatment led to a higher mass transfer rate than the OD process. UOD-treated seeds reached the optimal moisture content (10%) and water activity (aw < 0.650) faster than both fresh seeds and OD-treated seeds. Differential scanning calorimetry revealed that UOD pretreatment induced the loss of an important amount of water. X-ray diffraction analysis showed that ultrasound pretreatment did not affect the amorphous characteristics of pomegranate seed powder during drying. Practical applications: Ultrasound-assisted osmotic dehydration could be a novel approach for food preservation and processing, due to the combined effect of osmotic pressure gradient and ultrasonic effect on the surface of the food material. Ultrasound pretreatment can be implemented as an alternative pretreatment to reduce drying time and, consequently, processing costs. Ultrasound-assisted osmotic dehydration is gradually gaining attention as a pretreatment method due to its advantages which include preservation of antioxidant properties and bioactive compounds. This study provides information on the application of response surface methodology for the optimization of ultrasound-assisted osmotic dehydration of pomegranate seeds. © 2020 Wiley Periodicals LLC