Optimization of ultrasonic-assisted extraction of phenolic antioxidants from Malus baccata (Linn.) Borkh. using response surface methodology

In this study, the optimum extraction conditions for maximum recovery of the content of total phenolics (TPC) and total antioxidant abilities were analyzed for Malus baccata (Linn.) Borkh. using response surface methodology. The effects of ethanol percentage (X₁,%), ultrasonic power (X ₂, W) and extraction temperature (X₃, °C) on the total phenolic content (Y₁) and antioxidant ability (Y₂) were evaluated. A second-order polynomial model produced a satisfactory fitting of the experimental data with regard to total phenolic content (R² = 0.9942, P < 0.0001) and antioxidant ability (R² = 0.9966, P < 0.0001). The optimized conditions were ethanol concentration of 61.0%, ultrasonic power of 308.6 W, extraction temperature of 51.1°C for TPC and 60.5%, 311.4 W, 51.6°C for antioxidant ability, the predicted values agreed well with the experimental values. Results implied that the major phenolic compounds in obtained extracts as chlorogenic acid, quercetin-3-gal/glu, quercetin-3-xyl/ara, phloretin-2-xyloside, quercetin-3- rhamnoside, and phloridzin.