Influence of ultrasound and microwave on apparent density of fried potato strips and its kinetic modeling

Deep-fat frying process of foods is one of the common cooking methods. The process causes some changes in physical properties of foods such as apparent density. In this study, the effect of process conditions (temperature and time) as well as ultrasound and microwave pretreatments on apparent density of potato strips during deep-fat frying process was investigated. Ultrasound pretreatment was performed at frequencies of 28 and 40 kHz and microwave pretreatment was conducted at powers of 3 and 6 W/g on the potato slices. Then, the frying process was done at 150, 170 and 190°C for 1, 2, 3 and 4 min. Results showed that ultrasound and microwave pretreatments significantly reduce the apparent density of potato strips compared to control samples. In addition, apparent density was significantly decreased by increasing ultrasound frequency, microwave power, process time and temperature. Furthermore, five models were presented in order to predict apparent density considering the process conditions.