The effect of ultrasound and blanching on oil uptake during deep-fat frying of potato

Abstract

The aim of this study was to investigate the influence of ultrasound and blanching pretreatments on oil uptake and to model them on potato slices during deep-fat frying. Ultrasound pretreatments were applied at 40 kHz for 20 and 40 min and blanching pretreatments were done in hot water at 80˚C for 2 and 4 min. Then, frying processes were performed at 150, 170 and 190˚C for 90, 180, 270 and 360 seconds. To model the oil uptake as a function of time, four experimental proposed models and two empirical models available in the literature were used. In addition to the time, the oil uptake was modeled as a function of moisture content, density and shrinkage. Results showed that blanched samples for 2 min had the lowest oil uptake at the frying temperature of 150˚C. Furthermore, the combination of ultrasound pretreatment (at 40 kHz for 20 min) and blanching (for 2 and 4 min), decreased oil uptake at the frying temperatures of 150 and 170˚C. Moreover, experimental data were fitted well with empirical models. In addition, for determining the coefficients of the oil uptake models, some correlations were found by multivariate regression analysis in various conditions of the frying process.

Keywords

• blanching
• frying
• modeling
• oil uptake
• ultrasound