Effects of steaming with enzyme-assisted pretreatments on the physicochemicalproperties, phytochemical compounds, and antioxidant activities of Caricapapaya juice

The pectin in papaya fruits complicates juice extraction due to its viscous nature. Steam treatment has the potential to aid extraction by disrupting cellular membranes. However, heat treatment used in the processing of papaya juice has a substantial impact on the quality of the resultant juice. This study aimed to determine the effects of steaming with enzyme-assisted pretreatments on the physicochemical properties, phytochemical compounds, and antioxidant activities of papaya juice. Papaya fruit was cut to 2.5 cm3 and steamed for varying durations (0 (control), 2, 4, 6, 8 mins). Then, the fruit was blended into puree before being subjected to pectinase enzyme treatments at 20 parts per million (ppm) for 1 hr and pasteurised for 7 mins at 75℃. Steaming the fruit for up to 4 mins enhanced juice extraction yield by up to 56% compared to the control (51.67%). The total carotenoid content was significantly higher, reaching 756.0 µg/100 mL after 4 mins of papaya steaming compared to the control (629.2 µg/100 mL). Increasing steaming time significantly increased the papaya juice's total flavonoid and carotenoid content. However, the physicochemical properties of papaya juice exhibit a significant reduction with prolonged steaming time, accompanied by a considerable decline in total phenolic content (TPC) and ascorbic acid content. The papaya juice's antioxidant activities (DPPH, ABTS, and FRAP) experience a substantial reduction at 4 mins steaming pretreatment. This study determined that 4 mins was the most suitable steaming time for achieving higher yield and elevating high antioxidant content (carotenoid and flavonoid) in the papaya juice. Overall, this study provides valuable information for the application of steaming with pectinase enzyme-assisted pretreatments in papaya juice production.