Fish products and Byproducts Technology

Unit 11 - Chitin and Chitosan

11.1. Chitin and Chitosan
What is Chitin?
Chitin is the second most abundant naturally occurring biopolymer (after cellulose) and is found in the exoskeleton of crustaceans, in fungal cell walls and other biological materials. It is mainly poly (ß-(1-4)-2-acetamide- D-glucose), which is structurally identical to cellulose except that secondary hydroxyl on the second carbon atom of the hexose repeat unit is replaced by an acetamide group.

What is chitosan?
Chitosan is a natural polysaccharide comprising copolymers of glucosamine and N-acetylglucosamine, and can be obtained by the partial deacetylation of chitin, from crustacean shells, the second most abundant natural polymer after cellulose. Chitosan is derived from chitin by deacetylation in the presence of alkali. Therefore, chitosan is a co-polymer consisting of (ß-(1-4)-2-acetamido-Dglucose and (ß-(1-4)-2-acetamide-D-glucose units with the latter usually exceeding 80%.