An experimental design to obtain films from chitosan was elaborated with the incorporation of crosslinker (ethylene glycol diglycidylether), nisin and glycerol. The independent variables were chitosan concentration (0,7-2,3%), acetic acid concentration (0,3-3%) and molar ratio of crosslinking/polymer (0-4). Although there was a significant effect of the single independent variables on the films properties determined throughout the study, no interaction between them was noticed. Chitosan and gelatin blend films were also produced with different proportions, as well as bi-layered films. The rheology of the filmogenic solutions showed that crosslinking only takes place during film formation, and not when the crosslinking agent was added to the solution. We observed that the value of the storage and loss modulus as well as the viscosity, increased with concentration of chitosan. The films obtained were very hydrophilic. Even though the values were relatively high, there was less water absorption capacity and solubility in water and in acid, for central values of molar ratio crosslinker/polymer. Regarding the mechanical properties of the films, the tensile strength was positively affected by the decrease of pH and the increase of molar ratio crosslinker/polymer, whereas, the elongation at rupture was only affected by the chitosan concentration. As expected, the higher the proportion of chitosan on blend and bi-layer films the closer they resembled the straight for waned chitosan films in what mechanical behavior is concerned

Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia