Effects of superheated steam drying on the physical properties, functional characteristics, and antioxidant capacity of papaya powder

Carica papaya is high susceptibility to microbial degradation and enzymatic browning due to its high moisture content, significantly limiting its post-harvest shelf life and marketability. While various drying techniques have been explored to overcome these issues, there is a lack of comprehensive studies that establish the ideal parameters for superheated steam drying (SSD) to maximise the retention of bioactive compounds while enhancing the functional properties of papaya powder. This study aims to investigate the impact of superheated steam drying (SSD) time and temperature on the physiochemical attributes, functional properties, and antioxidant capacity of papaya powder. Papaya powders obtained from drying at different temperatures (100, 110 and 120 °C) and times (120 and 140 min) have been analysed for yield, colour, moisture content, water activity, functional characteristics, and antioxidant capacity. Papaya powder produced from drying at 100 °C for 120 min yielded the most due to its high moisture content. Increasing the drying time to 140 min resulted in the highest lightness (L* value) compared to other samples. Drying at 120 °C for 140 min increases solubility, increase hygroscopic and bulk density, and retains maximum retention of ascorbic acid, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities (ABTS assay) compared to other drying times and temperatures. Drying at 110 °C for 140 min retained a higher beta-carotene content than other samples. Results show a significant positive correlation between TFC and DPPH (r = 0.852), and ABTS (r = 0.719) at p < 0.01, contributing to papaya powder’s high antioxidant compounds and activity. Scanning electron microscope (SEM) analysis showed that particles at 120 °C for 140 min were the smallest. This can improve particle morphology, enhancing the exposure and stability of bioactive compounds. In conclusion, drying papaya at 120 °C for 140 min effectively preserves total phenolic content (TPC) and total flavonoid content (TFC), which subsequently enhances the powder's antioxidant activity and functional properties.