Optimization of Ultrasonic-Assisted Enzyme Extraction of Polyphenols from Burdock and Its Antioxidant Activity Evaluation

Abstract:

Optimization of the experimental conditions for extracting polyphenols from burdock by ultrasonic-assisted enzymatic hydrolysis method and evaluation of the antioxidant activities were performed. On the basis of single factor experiment，the extraction conditions of polyphenols was optimized using response surface methodology. Antioxidant capacity was determined by DPPH radical scavenging capacities，superoxide anion scavenging capacities as well as hydroxyl radical scavenging capacities. Results showed that the optimum extraction parameiers were as follows: ethanol concentration 45%，solid to liquid ratio 1∶20（g/mL），ultrasonic time 6 min，cellulase concentration 1.25 mg/mL，reaction time 80 min，reaction temperature 50℃. The extraction rate of polyphenols（41.33 mg/g） increased by 39.30% and 25.13% compared to treatment with ultrasonic or cellulose individually under optimal conditions. The polyphenols derived from burdock displyed strong antioxidant activity，and the antioxidant capacity of polyphenol has a dose effect on its mass concentration within a certain concentration range. Under the concentration of 0.5 mg/mL，the radical scavenging rate on DPPH was 55.66% which is close to that of Vitamin C with the same concentration.