Ultrasonic microwave-assisted vacuum frying technique as a novel frying method for potato chips at low frying temperature

The ultrasonic microwave-assisted vacuum frying (USMVF) was properly designed and tested as a novel frying technique for potato chips at low frying temperature in this work. The USMVF was carried out by the combination of ultrasound and microwave in the vacuum frying to shorten the frying time and improve the quality of products. Two frying temperatures (90 °C and 100 °C) were comparatively analyzed both in USMVF and microwave-assisted vacuum frying (MVF). Based on the analysis of drying kinetics and quality assessment, the USMVF markedly increased the moisture evaporation kinetics and effective moisture diffusivity, reducing 20-28% of the drying time compared with the MVF, especially at lower frying temperature. The oil uptake of fried potato chips was reduced in the USMVF with low frying temperature. The texture properties (crispness) and color of fried potato chips were greatly improved by the combination of ultrasound in MVF. The energy consumption in USMVF was also decreased compared to that in MVF, decreasing 20.4-24.7% depending on the frying temperature in this test. A more porous microstructure in USMVF samples was observed by SEM and helped to explain the effects of ultrasound. The drying data (moisture ratio versus time) were successfully fitted to the Logarithmic model.