Polyphenol assisted nano-reinforced chitosan films with antioxidant and antimicrobial properties

Active packaging with nano-reinforcement has appeared as an emerging strategy to replace the conventional plastic packaging films. In this contribution, Quercetin/rutin/vanillic acid incorporated chitosan nanocomposites with a reinforcement effect of cellulose derived cellulose nanocrystals (CNC) or chicken feather derived nanokeratin (NK) were developed using solvent casting method. Polyphenol incorporated CNC reinforced films displayed 69% increase in tensile strength whereas only 38% rise in strength was depicted by nano-keratin reinforcement. Quercetin incorporated CNC reinforced films exhibited 22% decline in film's permeability to water vapors and almost 38% upsurge in opacity. The crosslinking between hydroxyl, amino and carboxyl groups of polyphenols, Chitosan and CNC respectively was confirmed by FTIR. XRD and SEM analysis suggested dispersed nano fillers in chitosan matrix and depicted intercalated morphologies with rough surface. The thermal transitions of prepared films were found to be comparable to chitosan control. Quercetin incorporated CNC reinforced films exhibited 70% DPPH free radical scavenging activity with highest phenolic content. Quercetin and rutin incorporated CNC composites showed anti-microbial activity which may be due to polyphenols in the film's structure. Moreover, baby carrots wrapped with quercetin incorporated CNC reinforced chitosan films exhibited least weight loss and maintained overall acceptability over one-week storage. Comparatively, among all blends, combining quercetin and chitosan along with CNC reinforcement, can aid in development of active films with improved mechanical strength, enhanced UV protection, free radical scavenging ability and antimicrobial properties appropriate for food preservation.