Process Optimization for Ultrasound-assisted Ethanol Extraction of Polyphenols from Mulberry Leaf

Polyphenols are important medicinal active ingredients in mulberry leaves. Mulberry leaf powder was used as material for extraction of polyphenols with ultrasound-assisted ethanol extraction method. The results from single factor experiment under 160 W ultrasound power showed that ethanol concentration,material mass concentration,extraction temperature and extraction time could affect the yield of polyphenols from mulberry leaf. Orthogonal experiment demonstrated that the four factors affected the extraction were in the order of material mass concentration,extraction temperature,extraction time and ethanol concentration. The optimum extraction condition for mulberry leaf polyphenols was as follows: material mass concentration 33. 3 g /L,volume fraction of ethanol solution 60%,ultrasound power 160 W,extraction temperature 50 ℃,and extraction time 20 min. Under this optimized condition,the yield of polyphenols from mulberry leaf was 3. 51%. Compared with conventional ethanol extraction,ultrasound-assisted extraction can obviously shorten the extraction time and improve extraction efficiency.