水溶性壳聚糖只能溶于一些稀的无机酸或有机酸中，不能直接溶于水中，这在很大程度上限制了它的应用。
　　把甲壳素在均相条件下进行脱乙酰化反应，当脱乙酰度为百分之50左右时，水溶性壳聚糖能溶解于水。
　　一般的水溶性壳聚糖只能溶于一些稀的无机酸或有机酸中，不能直接溶于水中。水溶性壳聚糖又称脱乙酰甲壳素，由自然界广泛存在的几丁质经过脱乙酰作用得到的，化学名称为聚葡萄糖胺(1-4)-2-氨基-B-D葡萄糖。

　　很容易判(pan)断水(shui)(shui)溶(rong)(rong)(rong)性(xing)水(shui)(shui)溶(rong)(rong)(rong)性(xing)壳(qiao)聚(ju)糖(tang)(tang)(tang)，只要把它溶(rong)(rong)(rong)于水(shui)(shui)，首(shou)先看溶(rong)(rong)(rong)液(ye)有(you)没有(you)粘性(xing)，没有(you)粘性(xing)者是(shi)低分子甲(jia)壳(qiao)素或低分子水(shui)(shui)溶(rong)(rong)(rong)性(xing)壳(qiao)聚(ju)糖(tang)(tang)(tang);其(qi)次，往此(ci)水(shui)(shui)溶(rong)(rong)(rong)液(ye)中(zhong)(zhong)滴(di)(di)加几滴(di)(di)NaOH溶(rong)(rong)(rong)液(ye)，产(chan)生(sheng)浑浊或沉淀者，是(shi)水(shui)(shui)溶(rong)(rong)(rong)性(xing)壳(qiao)聚(ju)糖(tang)(tang)(tang)盐(yan)酸盐(yan)，因为其(qi)中(zhong)(zhong)的(de)盐(yan)酸被碱(jian)中(zhong)(zhong)和了，水(shui)(shui)溶(rong)(rong)(rong)性(xing)壳(qiao)聚(ju)糖(tang)(tang)(tang)不(bu)溶(rong)(rong)(rong)于中(zhong)(zhong)性(xing)或碱(jian)性(xing)的(de)水(shui)(shui)中(zhong)(zhong);如果滴(di)(di)加几滴(di)(di)HCl溶(rong)(rong)(rong)液(ye)而产(chan)生(sheng)浑浊，则(ze)是(shi)羧甲(jia)基(ji)水(shui)(shui)溶(rong)(rong)(rong)性(xing)壳(qiao)聚(ju)糖(tang)(tang)(tang)，因为羧甲(jia)基(ji)水(shui)(shui)溶(rong)(rong)(rong)性(xing)壳(qiao)聚(ju)糖(tang)(tang)(tang)实际是(shi)羧甲(jia)基(ji)水(shui)(shui)溶(rong)(rong)(rong)性(xing)壳(qiao)聚(ju)糖(tang)(tang)(tang)的(de)钠盐(yan)，如果此(ci)溶(rong)(rong)(rong)液(ye)被酸化(hua)，则(ze)不(bu)再是(shi)羧酸钠盐(yan)，而成了羧酸，它就不(bu)溶(rong)(rong)(rong)于酸性(xing)水(shui)(shui)中(zhong)(zhong):R一COONa + H ―→R-COOH+ Na式中(zhong)(zhong)R氨(an)基(ji)葡萄糖(tang)(tang)(tang)残基(ji)。