Sonication and thermal treatment of pineapple juice: Comparative assessment of the physicochemical properties, antioxidant activities and microbial inactivation

Sonication is a novel processing method that is perceived as a substitute for heat treatment to ensure the safety of juice while reducing the loss of nutrients during processing. The impacts of sonication and thermal processing on pineapple juice, including physicochemical properties, antioxidant activities, and microbial inactivation, were studied. Pineapple juice was sonicated at 100 W and 140 W (for 5, 10 and 15 min) and heat-treated at 70 °C, 80 °C and 90 °C (for 1 min). Results indicated minor alterations in physicochemical characteristics after sonication and thermal processing, while sonication treatment showed better retention of the color, clarity, and browning index of pineapple juice. Moreover, sonication significantly increased the bioactive compounds (total carotenoids, ascorbic acid, phenolics, and flavonoids) and boosted the antioxidant activity of pineapple juice compared to the heat-processed juice. Although sonication reduced the microbial load significantly with the increasing exposure time, it could not thoroughly inactivate microorganisms like thermal treatment. Therefore, optimal sonication processing conditions are required to be determined. This study will help the food processors utilize sonication treatment in pineapple juice processing plants to inactivate microorganisms thoroughly while also boosting the nutritional value.