Alkali process for chitin extraction and chitosan production from Nile tilapia scales

Chitosan is a biopolymer of wide application due to its characteristics and non-toxicity, presenting antimicrobial, antitumoral and cicatrizing activities. It is currently used as emulsifier, metal's chelating, edible biofilm and fat reducer. The variation in the deacetylation degree of this polymer gives differentiated functional properties. It is mainly obtained from crustaceans, but fish scales are also a potential source of this product, despite neglected so far. The aim of this study was to develop a method for chitin extraction and deacetylation for chitosan obtaining from Nile tilapia (Oreochromis niloticus) scales. Characterization showed that chitosan was completely purified. The chitin infrared spectrum presented a characteristic larger band in the region of 3,500 [cm.sup.-1], due to axial stretching vibrations of the OH group been completely purified, which disappeared in the chitin spectrum. However, a new band aroused at 1,640 [cm.sup.-1] due to the N[H.sub.2] deformation, which predominated over the band at 1,655 [cm.sup.-1], associated to the carbonyl (C=O) that tends to decrease, as the degree of deacetylation of chitosan increases. All bands observed were similar to those described in the literature. Although the yields were lower than the averages usually reported for crustaceans, they can be improved to obtain higher yields and deacetylation. Keywords: fish residue, chitin, chitosan, infrared, deacetylation, chemical processes. El quitosano es un biopolimero de amplia aplicacion debido a sus caracteristicas y no toxicidad, presentando actividad antimicrobiana, antitumoral y cicatrizante. Actualmente se utiliza como emulsionante, quelante de metales, biopelicula comestible y reductor de grasas. La variacion en el grado de desacetilacion de este polimero ofrece diferentes propiedades funcionales. Se obtiene principalmente de crustaceos, pero las escamas de pescado tambien son una fuente potencial de este producto, proceso descuidado hasta ahora. El objetivo de este estudio fue desarrollar un metodo para la extraccion de quitina y desacetilacion de quitosano a partir de escamas de tilapia del Nilo (Oreochromis niloticus). Esta caracterizacion mostro que el quitosano fue completamente purificado. El espectro infrarrojo de la quitina presento una ancha banda caracteristica en la region de 3,500 [cm.sup.-1], debido a vibraciones del estiramiento axial del grupo OH que ha sido completamente purificado, que desaparecio en el espectro de la quiti