Ultrasound-assisted extraction of polysaccharides from mulberry leaves

Ultrasound-assisted extraction (UAE) of polysaccharides from mulberry leaves was studied. The effects of four factors on the yield of polysaccharides were investigated. The results showed that optimum conditions were extraction power of 60 W, extraction temperature of 60 °C, extraction time of 20 min and ratio of water to raw material of 15:1 (ml/g). The three different methods (UAE, MAE and CSE) were compared for extracting polysaccharides from the mulberry leaves by SEM images. Totally, UAE had the largest yield of polysaccharides. The crude polysaccharides obtained from UAE were purified and two components (MPS-1 and MPS-2) were obtained. Their structure was analysed with chemical methods. From FT-IR, they were polysaccharides. MPS-1 had more functional groups than MPS-2. From HP GPC analysis, molecular weights of MPS-1 and MPS-2 were 24898D and 61131D, respectively. From GC analysis, MPS-1 was composed of Sor, Ara, Xyl and Glc, and MPS-2 was composed of Rha, Ara, Xyl, Glc, Gal and Man.