Influence of combined frequencies and various applied time combinations of ultrasound waves on moisture loss during frying of potato strips

Moisture loss and oil uptake are closely related during the process of deep-fat frying. The aim of this study was to evaluate the influence of ultrasound waves with combined frequencies on moisture loss kinetics during frying of potato strips as well as modeling the moisture loss. Ultrasound pretreatment was performed at 28 and 40 kHz for 30 minutes with separate and combined frequencies. Then, the frying process was done at 150, 170 and 190°C for 90, 180, 270 and 360 seconds. To model moisture loss, Fick’s second law was used. Effective moisture diffusion coefficient obtained from experimental data was between 1.823×10-8 - 4.377×10-8 m2/s. The average correlation coefficient between the experimental data and the data obtained from the Fick’s law was 0.96. The use of ultrasonic pretreatment with separate and combined frequencies increased the effective moisture diffusion coefficient. This increase was significant in some samples while it was insignificant in others. Empirical models were used to study the moisture loss kinetics during frying. In addition, effect of temperature on the effective moisture diffusion coefficient was calculated through the Arrhenius equation.