Quantitative Analysis by IR: Determination of Chitin/Chitosan DD DOI: http://dx.doi.org/10.5772/intechopen.89708

adopted. Deproteinization and demineralization can be carried out using chemical or enzymatic treatments. In the case of shrimp, the shell wall is thinner, which facilitates the isolation of chitin compared to other types of shells. The selected shells are then cleaned, dried, and ground into small shell pieces. Shrimp carapaces

We then develop the two essential steps for the preparation of chitin from the

The deproteinization of chitin consists in eliminating proteins; it is difficult because there is a breakdown of the chemical bonds between chitin and proteins. This is done using basic solutions in a heterogeneous way. Complete protein isolation is particularly important for biomedical applications. A wide range of chemicals have been tested as deproteinization reagents, including NaOH, Na2CO3, NaHCO3, KOH, K2CO3, Ca(OH)2, Na2SO3, NaHSO3, CaHSO3, Na3PO4, and Na2S. The reaction conditions vary considerably in each study. NaOH is the preferred reagent and is applied at a concentration ranging from 0.125 to 12 M, at different temperatures (up to 20°C) and a duration of treatment (from a few minutes to a few days). In addition to deproteinization, the use of NaOH results in partial deacetylation of chitin and hydrolysis of the biopolymer, which decreases its molecular weight.

Demineralization is a necessary step to produce chitosan. It consists of dissolving minerals, mainly calcium carbonate bound to chitin. Demineralization is generally carried out by acid treatment using HCl, HNO3, H2SO4, CH3COOH, and HCOOH [26, 27]. Of these acids, the preferred reagent is dilute hydrochloric acid. Demineralization is an acid–base reaction between carbonate ions and acids in water with

All the other minerals present in the crustacean cuticle react in the same way and give soluble salts in the presence of acid. Then, the salts can be easily separated by filtering the solid phase of chitin, followed by washing with distilled water.

Chemically, a kilogram of fresh shells provides about 40 g of dry chitin. After the chemical treatment, the grinding and sieving processes to obtain a homogeneous chitin cause losses of about 40%. The final yield is 2.5%, 25 g of chitin per kilogram of shell. Table 2 summarizes the operating conditions of chitin extraction

2 HCl þ CaCO3 ! CaCl2 þ H2O þ CO2 (1)

the release of carbon dioxide, as indicated in the following equation:

have the following average mass composition:

Modern Spectroscopic Techniques and Applications

• traces of lipids and organic pigments

carapaces, namely deproteinization and demineralization.

• 75% water

• 12% protein

• 4% chitin

• 9% mineral salts

2.1 Chemical deproteinization

2.2 Chemical demineralization

according to different sources.

110

Table 2. Chitin extraction conditions.
