Polysaccharide of chitin

Chitin is a major structural polysaccharide found in inveterate animals and lower plants. It is widely available biopolymer obtained principally from shrimp and crab shell waste.

It is occurs as highly ordered microfibrils in many species, in a variety of arrangements, from diatom spines to cell was components of many fungi and yeasts.

Chitin is a type of polysaccharide composed of an amino sugar and consisting of a straight chain molecule by binding D-glucosamines in which each amino sugar is acetylated by β-1,4 linkage.

Chitin

Among the three forms, α-chitin is the most abundant, crystalline, tightly compacted and stable form in which the chains are arranged in an anti-parallel fashion. α-chitin is found where extra hardness proves essential, whereas β- and γ-chitin provide toughness, flexibility and mobility.

Chitin is considered the second most plentiful biomaterial following cellulose. When chitin is deacetylated to about 50% of the free amine form, it is referred to as chitosan.

Chitin is produced by removing calcium carbonate and proteins from the shells. In the production of chitin, calcium carbonate is first dissolved by stirring the shells in dilute hydrochloric acid at ambient temperature.

Proteins are then extracted from the decalcified shells by threatening them with dilute aqueous sodium hydroxide; crude chitin is then obtained.
Polysaccharide of chitin