Filmes de quitosana reforçados com fibras de celulose para aplicações em embalagem de alimentos

Abstract

Chitosan is an artificial polymer obtained from the deacetylation of chitin, present in cell walls of fungi and exoskeletons of insects and crustaceans. Due to its biodegradable, biocompatible and antibacterial properties, its use in films for food packaging has been studied. However, its low mechanical properties still restrict its use. One of the ways to improve its mechanical properties and still keep it biodegradable would be through the incorporation of natural fibers in the polymer matrix. The objective of this work is to investigate the viability of using natural fibers as reinforcement in chitosan films for food packaging and to verify if their addition affects the properties of the composite. Chitosan solutions were be produced with 1.5% mass/volume dissolved in acetic acid 1.0% volume/volume with subsequent addition of 0.6% v/v of glycerol as a plasticizer. Mercerized sisal fibers with size of 0.5; 1.0 and 2.0 mm will be added to the solution, with a proportion of 10% on the mass of chitosan used and films will be produced from the drying in molds. Films with and without fiber were applied for tensile tests and solubility tests. Chitosan in both powder and film was chemically and thermally characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The antibacterial activity of chitosan was also measured using agar diffusion test and well microdilution test. The addition of fiber to the film promoted an increase in stiffness and tensile strength, while decreasing elasticity. The FTIR and TGA analyzes showed that in the film after drying there is no presence of acetic acid and there is a strong presence of glycerol. Antibacterial tests showed that chitosan has a moderate antibacterial ability, but that acetic acid when in solution also assists in inhibition. In the form of a solution, the inhibiting agent infiltrates the medium, but in the form of a film, it inhibits only the surfaces in direct contact. The fiber reinforced films produced have potential for use in food packaging, especially if applied in the form of coating, where the food is submerged in the solution and removed to form a film on the surface.