Impact of pulsed electric fields and ultrasound on the frying characteristics of sweet potato chips

Abstract

Sweet potato fries and chips are a popular snack worldwide. However, as the high oil and acrylamide contents in fried foods may contribute to increased risks of obesity, diabetes, hypertension and cancer, methods to reduce these harmful components have become a research focus. In this study, the impacts of pulsed electric fields (PEF) and ultrasound (US) on the frying kinetics and characteristics of sweet potato chips were investigated. The intensity of PEF treatment was set at E = 1.0 kV/cm with a total duration of t_PEF = 0.2 s; the energy applied in the PEF pre-treatment was 9.47 ± 0.5 kJ/kg. US treatment was performed at 53 kHz (10 s ON/1 s OFF), 180 W, and 25 °C for 30 min. Low-field nuclear magnetic resonance (LF–NMR) revealed that both PEF and US pre-treatment influence the binding force between water molecules in sweet potatoes. Reducing sugars in raw products treated with PEF, US, and PEF + US were significantly (p < 0.05) reduced by 33.3 %, 20.0 %, and 53.3 %, respectively. The first-order kinetics model provided a good fit for water evaporation during frying. The PEF, US, and PEF + US treatments resulted in oil content reductions of 32.3 %, 37.0 %, and 40.3 %, respectively, compared with the untreated samples. Pre-treatments also improved the color and textural characteristics of fried sweet potato chips. Furthermore, the acrylamide content was reduced by 55.28 % (549 µg/kg) with PEF + US pre-treatment. These results reveal a potential method for producing high-quality fried products.