Chitin and chitosan are produced with a thermochemical process from crab and shrimp shells’ Since protein, minerals and pigments are present in the structure of shrimp and crab shells, this process is divided into sub-branches for producing pure chitin. These are demineralization (caCo3) and the deproteinizationprocesses. (Tsigos et al., 2000), Acid is used for removal of minerals in chitin extraction with chemical method and base is used for removal of proteins. (No et al., 1989). % Components of sea shellfish are shown in Table 1.
Chitosan is a product obtained by N-deacetylation of chitin and is obtained by deacetylation process; this process is performed by using hot alkali solution. While chitosan deacetylation degree ranges from 40 o/o to 98 % of its molecular weight varies between 5×104 Da and 2×106 Da. (Mourya and Inamdar, 2008). N-deacetylation process
is carried out as chemically homogeneous or heterogeneous state. (Tsigos et al. , 2000).
Degrees of depolymerization and deacetylation are substantial parameters changing molecular weight of chitosan. These parameters limit or expand use of chitosan in different applications. (Mourya and Inamd, 2008). All properties of chitosan depend on degree of deacetylation, degree of depolymerization and dispersion during deacetylation of recurring units (Lamarque et al., Z00T).
Until recently, chitosan production was based on thermochemical process procedure conducted under harsh environment conditions. As a result of environmentally unsafe and uncontrolled reaction, the product was not produced as uniform and standard, And it was emerging as having different properties in heterogeneous range. In other words, the products so obtained were polymer communities in physical mixture state having non-specific properties and in high polydispersed structure with randomly deacetylated and different depolymerization (Tsigos et al. , 2000). Therefore, use of chitin deacetylas in chitosan production and development of enzymatic process have
ensured removal of the conditions posing disadvantage in chemical production. However, this method is seen as a fairly costly method in our current conditions.
Chitosan Properties and Application of Uses
Since chitosan is a polymer with the effect o high bioactivity and high biodegradable deacetylated amino groups, having capability of creating film and capacity of chelation, high adsorption capacity, high biocompatibility, antimutagenic and antitumor effect and due to other physicochemical properties, it has found its place in several applications of areas. If it is necessary to mention these properties, antibacterial properties can be mentioned in the first place. This property may vary according to type of bacteria, chitosan concentration, environment pH, solution
type used for chitosan, molecular weight of chitosan and degree of deacetylation.
Very effective results arising from polycationic natural structure in chitosan types up to L4 o/o of generally depolymerization have been obtained. In addition to this, antibacterial activity of low molecular weight chitosan is greater when compared with medium or high weight. The higher chitosan concentration, the more inhibition effect in bacterial killing property. It has been reported that this has exhibited more active and strong effect in microorganisms with no chitosan or its derivatives in its structure. (Kumar et.al, 2000J. General application of use area is provided in Table,
|. Treatment of metal ions, pesticides,
. Removal of dyes and radioisotopes
. Reverse osmosis membranes
|Agriculture||. Measurement of mold control in agricultural areai
. Fruit, vegetables and seed coating
|Cosmetics||. Skin and hair care products
. Toothpaste additive
|.Controlled release of drugs
. Artificial leather
. Operation Structures
. Contact lenses
. Treatment of severe burns
. Blood dialysis membranes
. Artificial blood vessel production
. Synthetic fibers
. Paper production
. Raw material in fiber production
. Film and sponge production
|. Antibacterial agent
. Antifungal agent