Intensification of bio-actives extraction from pomegranate peel via microwave irradiation: Effect of factors, optimization, kinetics, and bioactive profiling

Pomegranate (Punica granatum L.) peel is an appealing agri-food byproduct due to its high content of health-beneficial phytochemicals. However, the extraction processes may alter their bioactivity. A microwave irradiation treatment was applied to enhance the extraction efficiency. Extraction time, microwave power, and temperature were examined and optimized numerically using polynomial model and genetic logarithm. Time and temperature were the most influential factors in intensifying bioactives extraction. The optimal variables were 620 W microwave power at 74°C for 18 minutes (RSM), and 685 W power at 75°C for 24 minutes (ANN-GA). The obtained yields of total polyphenols, flavonoids, punicalagin, ellagic acid, and total hydrolyzable tannins contents were 165.53 mg GAE/g, 40.78 mg QE/g, 91.05 mg/g, 4.28 mg/g, and 130.82 mg TAE/g of pomegranate peel, respectively. The extract showed significant antioxidant capacities, with 65.74% DPPH inhibition and 71.26% ABTS inhibition. Several kinetic models were studied to define the extraction kinetics, with Peleg's model being the best fitting with the highest R2 (0:963-0.987) and lowest RMSE (0.95-5.08). LCMS analysis confirms the presence of 15 hydrolyzable tannins, with punicalagin and ellagic acid being the most abundant. These findings demonstrated the significant potential of microwave irradiation for extracting bioactives from fruit byproducts.