Process Optimization for Ultrasonic-assisted Extraction of Polyphenols from Mulberry Fruit by Response Surface Methodology

Polyphenols are one of the important components in mulberry fruit with antioxidant activity. To establish efficient and easy-operated extracting technology for mulberry polyphenols will facilitate development of mulberry polyphenol products for medical and healthcare uses. Fresh mature mulberry fruit was used as experimental material to extract polyphenols by ultrasonic-assisted ethanol extraction method. Based on single-factor experiments,the effect of ethanol concentration,extraction pH value,mass concentration of raw material,ultrasonic power,and extraction time on the yield of polyphenols from mulberry fruit were optimized by response surface methodology. Combined with regression analysis by Design-Expert software and validation tests,the optimized extraction process was determined as follows: ethanol concentration 60. 0%,extraction pH value 5. 0,mass concentration of raw material 0. 025 g /mL,ultrasonic power 405 W,and extraction time 30 min.Under this process condition,the yield of polyphenols from mulberry fruit was 3. 016%,and the predictive value was 3. 161%. The result indicated that the establishedmodel could be used to predict the extraction yield of polyphenols from mulberry fruit,and the optimized extraction process condition has certain practical value.