Chitin . Nitrogen carbohydrate , white in color, insoluble in water and organic liquids .
[ hide ]
- 1 Location
- 2 Properties
- 1 Use
- 3 Obtaining
- 4 History
- 5 See also
- 6 Source
It is found in the dermoskeleton of arthropods , to which it gives its special hardness, in the skin of nematelminths and in the cell membranes of many fungi and bacteria .
The properties of chitin and chitosan depend mainly on the source of production and the method of preparation, and these polymers differ from each other in their distribution, molecular mass and degree of acetylation. Among these, the formation of foams, emulsions, gels with polyanions stands out, and they retain moisture due to the presence of free amino groups which, when dissolved in acidified aqueous solution, acquire a positive charge.
In addition it is reported that chitosan controls the growth of bacteria , fungi and yeast and has been applied to remove these organisms in tissues of plants and food. It has been established that chitosan cannot be digested by humans so it is considered as a dietary fiber with zero caloric content.
It is the second most abundant natural polymer after cellulose . It is used as flocculating agent for water treatment, as agent for wound healing, as a thickener and stabilizer in foods and medicines, as resin for ion exchange . It is highly insoluble in water and in organic solvents due to the hydrogen bonds that the molecule presents . Chitin becomes soluble in dilute inorganic acids when it loses acetyl from the acetylamino group, becoming chitosan.
This natural compound has aroused great interest in researchers because annually large volumes (120,000 tons) of chitin are obtained from shellfish residues (which have 14-35% chitin associated with proteins) and also due to the environmental problem caused by its slow degradation. The result of these investigations has been satisfactory due to the use of chitin and chitosan in the application of the pharmaceutical, food, and cosmetic industries, among others.
Chitosan is the main derivative of chitin, which can be obtained through a simple chemical deacetylation process. Under this term a family of copolymers is grouped with differences in the number of deacetylated units and in the molecular weight.
Chitin was first isolated in 1811 by Braconnot from some higher fungi (Fungi) as an alkali-resistant fraction and called it fungin. In 1823 Odier isolated insoluble residue solutions KOH of the elytra of a beetle and gave the name of chitin, of the Greek chiton, or tunic coverage. Odier identified the chitin in the crab’s demineralized shell and suggested that it is the base material for the exoskeleton of all insects and possibly arachnids.