通过醇沉、酶解和超滤等方法，分离提取甘蔗混合汁中的粗葡聚糖，并以凝胶渗透色谱( GPC) 测定其相对分子质量分布; 然后，采用葡聚糖酶降解混合汁中的葡聚糖，通过GPC 及离子色谱研究葡聚糖的相对分子质量及浓度变化规律．结果表明: 混合汁在室温下静置20 h 后，生成的葡聚糖相对分子质量主要为1．02 × 106和3．57 × 103 ; 随着酶解时间的延长，葡聚糖相对分子质量明显下降;葡聚糖酶可将葡聚糖降解为较小聚合度的多糖，酶解产物主要以低聚合度糖形式存在;葡聚糖浓度变化与其相对分子质量有关．

The crude dextran was separated and purified from the mixed juice ( MJ) of sugarcane through ethanolprecipitation,enzymatic hydrolysis and ultrafiltration,and the corresponding relative molecular mass distributionwas characterized by means of GPC. Then,dextranase was used to hydrolyze the dextran in the MJ,and the changelaws of the relative molecular mass and concentration of dextran during the enzymatic hydrolysis were investigated bymeans of GPC and IC.The results show that (1) the relative molecular masses of the dextran in the MJ stored atthe room temperature for 20h are mainly 1.02 × 106 and 3.57 × 103 ; (2) the relative molecular mass of the dextransignificantly decreases with the extension of the reaction time; (3) dextranase can hydrolyze the dextran into theoligosaccharides，which are the final major products; and (4) the concentration change of dextran is related to thecorresponding relative molecular mass change.