Optimization of Ultrasound Assisted Extraction of Phenolic Compounds and Antioxidants from Grape Peel through Response Surface Methodology

Functional components from Campbell Early grape peel were extracted by ultrasound-assisted extraction technology. The experiments were carried out according to a five level, three variable central composite rotatable design. The best possible combinations of extraction variables were obtained for the maximum phenolic compounds and antioxidant activities of grape peel extracts using response surface methodology. The optimal conditions include 53.14% ethanol, 46.03℃ temperature and 24.03 min time for the maximum total phenolic compounds (6.70 mg GAE/100 mL) and 53.06% ethanol, 50.65℃ temperature and 25.58 min time for the maximum antioxidant activity (555.90 mg/L). Under these conditions, the experimental total phenolics were 6.67 mg GAE/100 mL and antioxidant activity was 554.84 mg/L of the grape peel extract, which is well matched with the predicted values.