Pulsed ultrasound-assisted extraction of bioactive compounds from papaya pulp and papaya peel using response surface methodology: Optimization and comparison with hot water extraction

This article focusses on the pulsed ultrasound-assisted extraction (PUSAE) of nutritionally significant bioactive components from papaya pulp (PP) and papaya peel (PPEE) system. The effects of independent process variables such as sonication time (5 - 20 min), extraction temperature (40-70 degrees C), and solid to liquid ratio (loading ratio) (0.2-0.5 g/mL) on the yield of response variables such as total flavonoids (TF), total phenols (TP), antioxidant activity (AOA), and vitamin C (VC) from papaya pulp (PP) and papaya peel (PPEE) system were investigated using a face centred design (FCD) of the response surface methodology (RSM). For comparative analysis, findings from the hot water extraction process (HWEX) were compared with the optimal results of this study. According to the findings, the bath type pulsed ultrasound-aided system yielded 80.87-169.16 mg GAE/g total phenols (TP), 31.29-92.9% antioxidant activity (AOA), and 28.52-164.94 mg/100 g vitamin C (VC) for the PP case and 97.46-145.44 GAE/g sample total phenols (TP), 97.36-292.2 mg QE/g total flavonoids (TF), and 46.51- 89.17% antioxidant activity (AOA) for the PPEE case. The investigations confirmed that the PUSAE technique outperformed the HWEX (105 mg GAE/g sample total phenols (TP), 89.4 mg/100 g vitamin C (VC), and 76.50% antioxidant activity (AOA) for PP case and 88.5 mg GAE/g sample total phenols (TP), 145 mg QE/g vitamin C (VC), and 71.5% antioxidant activity (AOA) for PPEE case) quite effectively for both PP and PPEE systems. Furthermore, the study revealed that the PP extract contained the highest level of bioactives when compared to the PPEE system. These findings suggest that the pulsed mode ultra-sonication process has more potential than traditional extraction methods (such as soxhlet extraction, maceration, percolation etc.) for producing papaya pulp and papaya peel aqueous extract for medicinal and functional food applications.