Preparation and functional characterization of the bio-composite film based on chitosan/polyvinyl alcohol blended with bacterial exopolysaccharide EPS MC-5 having antioxidant activities

In this study, the plate casting method was successfully used to prepare biocomposite films containing EPS from probiotic Enterococcus faecium MC-5 in combination with PVA and chitosan. The findings demonstrated that EPS was uniformly distributed in the film matrices and significantly improved the physicochemical properties of the resulting composite films. The development of intermolecular connections between the polymers was detected by high tensile strength and low water vapour transmission rate. EPS plays an important role in limiting the passage of UV- and visible light radiations through the films. FT-IR analysis was used to determine the molecular compatibility between the functional groups of the blended films made up of chitosan-EPS and PVA-EPS. The TGA results showed that composite films have a significant degree of thermal stability. The presence of amorphous peaks in the composite film was confirmed by XRD analysis. The EPS blended films displayed a greater antioxidant property than the PVA and chitosan films, as determined by DPPH and hydroxyl radical scavenging activities. Interestingly, the EPS-derived films showed enhanced metal chelation activity and strong antibacterial properties against Listeria monocytogenes and Staphylococcus aureus. EPS-based composite films performed better than chitosan and PVA films in terms of degradation rate. The overall functional characteristics of the EPS blended films suggested that they could be used as a packaging material to replace or reduce the use of conventional petroleum-based packaging materials.

Automated summary

In this study, biocomposite films containing EPS from probiotic Enterococcus faecium MC-5 were successfully prepared using the plate casting method and combined with PVA and chitosan. The EPS was evenly distributed in the films, improving their physicochemical properties. The intermolecular connections between the polymers were detected, resulting in high tensile strength and low water vapor transmission rate. The EPS-based films showed a greater antioxidant property, metal chelation activity, and antibacterial properties compared to chitosan and PVA films. They also had a higher degradation rate, suggesting their potential as sustainable packaging materials.