ABSTRACT
Chitosan is a natural nontoxic biopolymer produced by the deacetylation of chitin, a major component of the shells of crustaceans, such as crab, shrimp, and crawsh. Currently, chitosan has received considerable attention for its commercial applications in the biomedical, food, and chemical industries (Knorr 1984; Kurita 1998; Razdan and Pettersson 1994). Chitosan contains three types of reactive functional groups, an amino/acetamido group as well as both primary and secondary hydroxyl groups at the C-2, C-3, and C-6 positions, respectively. The amino contents are the main reason for the differences between their structures and physicochemical properties as well as are correlated with their chelation, occulation, and biological functions. Chitooligosaccharides (COS) are the degraded products of chitosan or chitin, which have recently been produced by several methods such as enzymatic and acidic hydrolysis. Enzymatic preparation methods have received great attention because of their safety and ease of control. Many nonspecic enzymes, such as cellulases,
13.1 Introduction .......................................................................................................................... 223 13.2 Physico-Chemical Properties of Chitin and Chitosan Derivatives.......................................224 13.3 Chitin and Chitosan Oligosaccharides Preparation Methods ...............................................225 13.4 Biological Activity ................................................................................................................225
