This study investigates the antibacterial action of chitosan‐based nanofibers (CNFs) obtained by the electrospinning process on the permeability of bacterial membranes. The bactericidal efficiency of CNFs was first determined against Gram‐negative Escherichia coli and Salmonella Typhimurium, and Gram‐positive Staphylococcus aureus and Listeria innocua bacteria as a baseline. The results strongly suggest that CNFs interact with the negatively charged bacterial cell wall causing membrane rupture and inducing leakage of intracellular components among which are proteins and DNA. Results clearly indicate that the release of such components after contact with CNFs is an indication of membrane permeabilization and perforation, as pore formation was observed in transmission electron microscopy (TEM). This work suggests a plausible antibacterial mechanism of action of CNFs and also provides clear evidence in favor of chitosan as a bacterial membrane disruptor and perforator. As a result, CNFs can find promising applications as bioactive food packaging materials capable to extend shelf life of food products while inhibiting the spread of alteration flora and foodborne pathogens.

Shelf life and safety of minimally processed food are crucial for both consumers and the food industry. This study investigates the in vitro and in situ efficiency of electrospun chitosan‐based nanofibers (CNFs) as inner part of a multilayer packaging in maintaining the quality of unprocessed red meat. Activated CNF‐based packaging (CNFP) were obtained by direct electrospinning of chitosan/poly(ethylene oxide) solutions on top of a conventional multilayer food packaging. The electrospinning solutions were firstly characterized at the molecular level, mainly in terms of zeta potential and viscoelastic properties, and the evolution of the conformational structure was correlated to the nanofiber formation process. The oxygen and water vapor barrier properties of CNF‐based (CNFP) meat packaging were also investigated. The in vitro antibacterial activity of CNFs was determined against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus, and Listeria innocua, bacteria commonly incriminated in the alteration of food products. The efficiency of the CNFP materials against meat spoilage by E. coli was also assessed. Our results indicate that the electrospinning of CS is a multifactorial process and fiber formation requires the choice of a good solvent, high electrical conductivity, moderate surface tension, optimum viscoelastic properties, and sufficient chain flexibility and entanglement. The results also indicate that all the tested bacterial strains were significantly sensitive to the action of CNFs. The in situ bioactivity against E. coli showed the potential of CNFP as bioactive nanomaterial barriers to meat contamination by extending the shelf life of fresh meat up to 1 week.

This study investigates the antibacterial mechanism of action of electrospun chitosan-based nanofibers (CNFs), against Escherichia coli, Salmonella enterica serovar Typhimurium, Staphylococcus aureus and Listeria innocua, bacteria frequently involved in food contamination and spoilage. CNFs were prepared by electrospinning of chitosan and poly(ethylene oxide) (PEO) blends. The in vitro antibacterial activity of CNFs was evaluated and the susceptibility/resistance of the selected bacteria toward CNFs was examined. Strain susceptibility was evaluated in terms of bacterial type, cell surface hydrophobicity, and charge density, as well as pathogenicity. The efficiency of CNFs on the preservation and shelf life extension of fresh red meat was also assessed. Our results demonstrate that the antibacterial action of CNFs depends on the protonation of their amino groups, regardless of bacterial type and their mechanism of action was bactericidal rather than bacteriostatic. Results also indicate that bacterial susceptibility was not Gram-dependent but strain-dependent, with non-virulent bacteria showing higher susceptibility at a reduction rate of 99.9%. The susceptibility order was: E. coli > L. innocua > S. aureus > S. Typhimurium. Finally, an extension of one week of the shelf life of fresh meat was successfully achieved. These results are promising and of great utility for the potential use of CNFs as bioactive food packaging materials in the food industry, and more specifically in meat quality preservation.

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