Influence of ultrasound on the microbiological, physicochemical properties, and sensory quality of different varieties of pumpkin juice

This study has investigated the effect of ultrasound (US) as an emerging non-thermal sterilization technique on microbial growth and quality changes in three freshly squeezed pumpkin juices (Cucurbita maxima Duchesne, Cucurbita moschata Duchesne, and Cucurbita pepo L.).The three pumpkin juices were ultrasonicated at different ultrasonic power (0–400 W), time (0–20 min), and temperature (0–30 °C), and the total colony counts of the treated pumpkin juices were less than 5 log CFU/mL, which complied with the food safety and consumption standards. Based on these results, we further investigated the effects of different ultrasonic power (25 kHz, 10 min, 20 °C, 0–400 W) on the physicochemical properties and sensory quality of the three pumpkin juices. The physicochemical properties (color, sugar content, organic acid content, soluble solids, and carotenoids) of treated pumpkin juice were retained or improved to some extent. The antioxidant capacity was also increased by 9.09%, 10.25%, and 16.9% compared to the untreated group. During sonication, the particle size of all samples decreased significantly, the microstructure broke down significantly, and the sensory qualities of pumpkin juice were well preserved after sonication. •Pumpkin juices were ultrasonicated with a significantly higher sterilization effect.•Ultrasound increased the carotenoid content and the antioxidant activity.•Ultrasound reduced the enzyme activity and particle size of the three pumpkin juices.•Ultrasound destroys the sample structure,the higher the power the greater the damage.•Ultrasound had no significant effect on the sensory evaluation of the pumpkin juice.