Estudos para a extração de quitina, obtenção e modificação química de quitosana via reação de Zincke e preparação de filmes à base de quitosana para aplicação em embalagens de alimentos

Abstract

The growing concern for the environment increased the look for biodegradable polymers-based that is eco-friendly and can be applied in many areas. Chitosan stands out due to its properties, such as biocompatibility, biodegradability, non-toxicity, and antimicrobial activity, which is attributed to its polycationic nature. The first chapter of this work describes the studies carried out regarding the acquisition of chitin from the residue of the Brazilian fishing industry, the pink shrimp shell, through biological method using the fungus Aspergillus niger. The attempts made to obtain chitosan from the chemical deacetylation of the material extracted from the shrimp shell were also described. In chapter 2, an unprecedented chitosan derivative, Q1, containing a pyridine ring directly linked to the chitosan monomeric glycosamine unit was synthesized from the quaternization of the primary amino group with a Zincke salt in a never-before seen strategy in literature. The characterization of the new material was carried out through IR spectroscopy, 13C solid-state NMR and thermogravimetric analysis (TGA). Due to the permanent positive charge on nitrogen atoms in the Q1 structure, this derivative has potential application as antimicrobial agent. Due to its inherent properties, such as biocompatibility, biodegradability, chitosan has been explored for the preparation of films for use as food packaging to substitute for the packaging petrochemical-based that causes environmental damage. Thus, in the third chapter of this work, chitosan-based films were obtained for application as food packaging and coating, their mechanical properties were analyzed and the ability of these films to maintain fruit quality was evaluated. The results showed that the mechanical properties of the films improve with the addition of the glycerol plasticizer. When applied as a coating, films containing didecyl-dimethylammonium chloride, an antimicrobial agent, were more effective in extending the shelf life of strawberries and bananas. However, when applied as films in packaging, was observed that the addition of plasticizer and antimicrobial agents increased water absorption by the film, which affected the quality of packaged strawberries.