Chitosan is a polymer commonly found in nature. It is obtained from chitin , which is the structural material of shellfish ( shrimp, crab , crayfish, krill ) , insects , fungi and bacteria. It is a polysaccharide with a molecular structure very similar to cellulose. As a compound of natural origin , non-toxic and biodegradable , it is completely safe for the environment.
In terms of chemical structure is a polysaccharide made up of many particles aminosugar interconnected β 1-4 bond . This is chitozamina aminosugar (D- glucosamine ) which is a derivative of D - glucose , in which the OH group in the second position is substituted by amino (NH2). For comparison, cellulose is a polysaccharide composed of D - glucose particles also linked β1 - 4 bond.
The term chitosan is defined compounds that arise in the process of deacetylation of chitin, as a result of concentrated alkali at elevated temperature which leads to the gradual elimination of the acetate groups and the formation of free amine groups in the biopolymer glycosidic rings.
It is assumed that the natural form of the chitin present in the form of partially acetylated i.e. by OH or NH 2 group is attached acetyl group CH3 -C = O (Furda 1983).
It is interesting that despite the close relationship with the cellulose, is absent in higher plants , has however in relation to their very high biological activity min. increasing plant resistance to adverse environmental conditions for fungal and bacterial infection.