Influence of chemical treatment on yield and quality of chitosan from crabs exoskeletons

There is a significant excess of crabs exoskeletons residues that impact the environment, and chitosan obtaining from these materials is important due to its high applicability; therefore it is necessary to study the effect of chemical processes on the properties and comercial quality of this biopolymer. Six methods by changing the processes of demineralization, deproteinization, depigmentation and deacetylation to obtain six chitosans were evaluated. Demineralization was the process with the greatest influence on the yield and purity of chitin. The infrared spectra corroborated the obtaining of the chitosan with the applied methods, presenting deacetylation degree values between 78.77 +/- 3.99 to 93.11 +/- 0.36%. M3 and M6 methods were more efficient where it was posible to obtain two biopolymers with higher purity and good chemical, physicochemical and microbiological properties. The conditions for chitosan obtaining have an effect on the final quality of product.