ABSTRACT
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1.1.1 Discovery and Origin
Chitosan usually exists in nature as chitin, which is a natural macromolecular compound, namely, a polysaccharide formed by connecting N-acetyl-2-amino-2-deoxy-d-glucoses through β-(1,4) glycoside bonds. The structural formula of chitosan is shown in Figure 1.1. Chitosan is formed when some acetyls are removed from chitin. Usually, products with over 60% deacetylation degree (DD) or that can be dissolved in dilute acid are called chitosan.
