Coupled effect of ultrasound, microwave and osmotic dehydration pretreatments on water loss kinetics during deep-fat frying of potatoes

The purpose of this study was to model water loss during deep-fat frying of potato slices pretreated with ultrasound (frequency of 40 kHz for 10 and 30 min), microwave (power of 5 W/g for 5 min) and osmotic dehydration (sodium chloride solution at concentrations of 1 and 3% and temperature of 40°C for 3 hours). Diffusion Fick's law was used to model water loss during the frying process. Ultrasound pretreatment for 10 min decreased the effective moisture diffusion coefficient and water loss rate from the potatoes. Moreover, a number of experimental models were used to model water loss during the process. Also, using the Arrhenius equation, effect of temperature on the effective moisture diffusion coefficient was investigated. With increasing frying temperature, effective moisture diffusion coefficient increased logarithmically. On the other hand, using multivariate regression analysis, the water loss model constants as a function of various process conditions (concentration of osmotic solution, ultrasound time, microwave power and frying temperature) were obtained. In general, application of microwave and osmotic dehydration pretreatments as well as the combination of these pretreatments with ultrasound decreased the initial moisture content of the potatoe strips.