Empirical shrinkage modeling of potato strips pretreated with ultrasound and drying during deep-fat frying

Modeling the relationships between variables during deep-fat frying of food products can be a useful tool for optimal control of the process conditions، thus increasing the quality of the final fried product. This study investigated the effect of ultrasound and drying pretreatments on the shrinkage rate of fried potato strips; shrinkage of the samples was modeled as a function of process time. Ultrasound pretreatment was performed at 28 and 40 kHz for 15 min and drying pretreatment was conducted at 80°C for 8 and 15 min. Frying was done at 150، 170 and 190 °C for 60، 120، 180 and 240 s. In addition to model shrinkage، the experimental data were fitted to the six empirical models proposed in this study; to determine the best model، R2 and RMSE indices were used. The results showed that، applied separately، ultrasound pretreatment reduced the shrinkage of fried samples and drying pretreatment reduced the shrinkage when compared to the control samples. The applied models were well fitted to the experimental data and showed high R2 and low RMSE values. The use of ultrasound pretreatment is a promising method to improve qualitative and quantitative properties of fried products، including decreased sample shrinkage rate. The models proposed in this study can be useful to the deep-fat frying process and help control the quality and shrinkage rate of the final product.