Pure chitosan was prepared from cuticle of crab shells by hydrothermal methods. The hydrothermal treatment was useful for demineralization, deproteination and deacetylation of cuticle. The hydrothermal treatment of cuticle with 2M HC1 solution at 120 °C for lh brought about demineralization up to 100% (Fig. 2), then the demineralized product was deproteinated and deacetylated significantly by the hydrothermal treatment with 15 M NaOH solution at 150 °C for 1 h. These processes of deproteination and deacetylation could be carried out at the same time. Furthermore, these hydrothermal treatments brought about a considerable reduction in time (Fig. 4). Highly deacetylated chitosan from cuticle thus treated hydrothermally had molecular weight of about 7.4x104.
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