Moisture Content and Oil Uptake in Potatoes (Cultivar Satina) During Deep-Fat Frying

In this study, the effect of ultrasonic sound (at 20- and 40-kHz frequency for 15min) and drying (at 60 degrees C for 15min) pretreatments on the moisture content and oil uptake of potato slices (cultivar Satina) during deep frying were studied. The potato slices were fried at temperatures of 170 and 190 degrees C for 5, 7 and 10 min. Samples pretreated with ultrasound at 20 kHz had higher moisture contents than those receiving the 40-kHz pretreatment. The highest moisture content was obtained at 20 kHz and frying at 170 degrees C for 5 min. On the other hand, samples pretreated with ultrasound at 40 kHz had higher effective water diffusivity coefficient and activation energy than those pretreated at 20 kHz. The highest effective water diffusivity coefficient was obtained at 40 kHz and frying at 190 degrees C for 5min, whereas the highest activation energy belonged to pretreatment with 40 kHz and frying at 170 degrees C for 10 min. The range for effective water diffusivity coefficient was 6.95x10(-8) to 8.80x10(-8)m(2)s(-1) and that for activation energy was 13.161 to 16.307 kJ mol(-1). In addition, samples pretreated at 40 kHz had a lower oil uptake than those pretreated at 20 kHz. The highest oil uptake took place at 20 kHz, with frying at 170 degrees C for 10 min. Regression analysis revealed that an exponential model was best for predicting variations in moisture content and oil uptake of potato slices.