Demineralization, chitin isolation

Chitin isolation processes are generally performed through the following consecutive steps raw material conditioning, protein extraction (deproteinization), removal of inorganic components (demineralization) and decolouration. This sequence is preferred if the isolated protein is to be used as food additive for livestock feeding. Otherwise, demineralization can be carried out first [10]. A brief account of these processes will be given below. A more detailed description of chitin isolation (and chitosan preparation) can be found elsewhere [5, 8, 11]. 

Keywords Chitin isolation, demineralization, deproteinization, natural whiskers. 

There are many traditional methods for isolation of chitin oligomers. The procedures involved acid hydrolysis, neutralization, demineralization, fractionation by charcoal-celite column, fractionation by high-performance liquid chromatography (HPLC), and lyophilization. 

The isolation of chitin from shellfish waste consists of three steps deproteinization (DP), demineralization (DM), and decolorization (DC) whereby the order of the first two steps is generally considered irrelevant if protein or pigment recovery is not an objective (Shahidi and Synowiecki 1991). Chitin is further deacetylated (DA) to make chitosan or other products for a wide array of applications. Both chemical and enzymatic non-continuous batch methods are widely used on an industrial scale for the production of chitin, chitosan, and COS. 

Chitin and chitosan rarely occur in a pure, easily isolated form. A substantial effort has been made to develop chemical, mechanical, and enzymatic methods to obtain purified materials (25). The usual method of obtaining chitin involves the chemical treatment of shell fish wastes from the crab and shrimp industries. The first step is to demineralize the shell with dilute hydrochloric acid at room temperature. This is followed with a deproteinization step with warm dilute caustic. This yields a partially deacetylated chitin, which may then be further deacetylated to chitosan. Figure 3 shows the underlying chitin matrix in the crab shell and its microfibrillar... 

---