Optimization of ultrasound-assisted deep eutectic solvent extraction of bioactive compounds from pomegranate peel using response surface methodology

The efficient extraction of polyphenols from pomegranate peels using a deep eutectic solvent (DES) and ultrasound-assisted extraction (UAE) was investigated. A Box-Behnken design was used to investigate the effects of four independent variables (water content, liquid-to-solid ratio, ultrasonic power, and extraction time) on total polyphenol content (TPC), punicalagin content (PC), and ellagic acid content (EC). Optimized DES-based UAE conditions were as follows: TPC (water content, 29.30%; liquid-to-solid ratio, 53.50 mL/g; ultrasonic power, 238.20 W; extraction time, 29.50 min), PC (water content, 25.65%; liquid-to-solid ratio, 44.20 mL/g; ultrasonic power, 120 W; extraction time, 20 min), and EC (water content, 33.13%; liquid-to-solid ratio, 60 mL/g; ultrasonic power, 300 W; extraction time, 20 min). Under these optimal conditions, the experimental values for TPC, PC, and EC were 67.50 mg GAE/g, 130.65 mg/g, and 2.04 mg/g, respectively; these values were consistent with the predicted values.