Abstract: This study was concerned with the extraction, separation and purification of polysaccharides from pear pomace from juice processing and the analysis of their relative molecular mass, monosaccharide composition and structures. The results showed that a maximum yield of polysaccharides of 62.375 mg/g was obtained by ultrasonic-assisted extraction method under the following conditions: ratio of water to material 1:13 (g/mL), extraction time 60 min, ultrasonic power 132 W and extraction temperature 57 ℃. The best efficiency of protein removal from the polysaccharides was achieved using the Sevag method combined with papain; the process was easy to operate and time saving and led to maximum removal efficiency (75%) while reducing polysaccharide loss (24.71%). A maximum decolorization rate of 78.56% and a minimum polysaccharide loss of 25.86% were obtained by H2O2 treatment. A homogenous polysaccharide (LPB-C) was obtained after purification of the crude extract by DEAE-52 cellulose column chromatography. The viscosity average molecular mass of LPB-C was determined to be 8.47 × 104 g/mol, consisting of mannose, glucose, rhamnose and xylose in a molar ratio of 3.3:2.3:10.6:23.2. LPB-C was identified as a pyranoid polysaccharide containing beta glycosidic bonds. These results provide a basis for the development and utilization of pear pomace.

Key words: pear residue, polysaccharide, extraction, separation and purification, structural characterization