Graphene reinforced Chitosan-Cinnamaldehyde derivatives films: antifungal activity and mechanical properties

Bioactive food-preserving systems are based on the use of a natural antimicrobial agent loaded in a carrier material, which is able to trigger its release once necessary and to control the rate of release, thereby exerting either lethal or inhibitory effects against food pathogens or spoilage microorganisms. In this study the Schiff base of chitosan was synthesized by the reaction with cinnamaldehyde at different concentrations. Cinnamaldehyde is an aromatic α,ß-unsaturated aldehyde, and the major component in essential oils from some cinnamon species. It has been shown to exert antimicrobial activity against a wide range of microorganisms including bacteria, yeasts, and mould. The formation of the Schiff base is reversible under suitable conditions, and this might allow the release of the active cinnamaldehyde from chitosan, used as the carrier. The reaction kinetics was investigated by means of rheological analyses and infrared spectroscopy was used to assess the efficacy of the functionalization. Cinnamaldehyde-functionalized chitosan films were then prepared and tested antifungal properties in vitro. Moreover, the effect of the addition of expanded graphite sonicated stacks was evaluated in term of mechanical properties.