Response surface optimization, kinetic modeling, and thermodynamic study for ultrasound-assisted extraction of dietary fiber from mango peels and its structural characterization

Mango peels, a major mango byproduct, are considered to possess high polysaccharide content, such as dietary fiber. In the present study, RSM was used to obtain the optimal conditions (liquid to solid ratio (49.8:1), temperature (26 degrees C), amplitude (38.6%), and treatment time (8.6 min)) for ultrasound-assisted extraction of dietary fiber. The extraction yield (73.5%) was further enhanced by using enzymatic treatment (alpha-amylase, protease, amyloglucosidase) after ultrasonication. Extraction kinetics indicated pseudo second-order model as most suitable model with R-2 > 0.9. Thermodynamic parameters for SDF (triangle G = - 15 to - 12.44 kJ/mol, triangle H = 51.45, and triangle S = 0.122) and IDF (triangle G = - 8.55 to - 6.52 kJ/mol, triangle H = 31.49, and triangle S = 0.077) extraction indicated spontaneous, endothermic, and irreversible nature of the process. SEM images indicate positive effect of sonoenzymolysis technique in enhancement of functional properties of dietary fiber fractions, whereas, FTIR analysis (3700-3000 cm(-1), 2920-2930 cm(-1), 1620 cm(-1), and 1430 cm(-1)) confirmed the expected functional groups in SDF and IDF. Overall, extraction of dietary fiber using ultrasound-assisted enzymatic technique could be an economical and eco-friendly route for valorization of mango byproducts.