Microbial load reduction in stored raw beef meat using chitosan/starch-based active packaging films incorporated with cellulose nanofibers and cinnamon essential oil.

Food safety is a global concern due to the risk posed by microbial pathogens, toxins and food deterioration. Hence, materials with antibacterial and antioxidant properties have been widely studied for their packaging application to ensure food safety. The current study has been designed to fabricate the chitosan/starch-based film with cinnamon essential oil (CEO) and cellulose nanofibers for active packaging. The nanocomposite films developed in this study were characterized by using UV-Vis Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), and Gas Chromatography-Mass Spectroscopy (GC-MS). The biodegradability, hydrodynamic, mechanical, antioxidant and antibacterial properties of the films were also evaluated. From the results, the addition of CEO and cellulose nanofibers was found to enhance the antimicrobial and material properties of the film. FE-SEM analysis has also revealed a rough and porous surface morphology for the developed nanocomposite film. FT-IR analysis further demonstrated the molecular interactions among the various components used for the preparation of the film. The film has also been shown to have antibacterial activity against Staphylococcus aureus and Escherichia coli. Furthermore, the film was found to reduce the bacterial load of the stored beef meat when used as a packaging material. The study hence provides valuable insights into the development of chitosan/starch-based films incorporated with CEO and cellulose nanofibers for active food packaging applications. This is due to its excellent antimicrobial and physicochemical properties. Hence, the nanocomposite film developed in the study can be considered to have promising applications in the food packaging industry.

ZnO nanoparticles induced biofilm formation in Klebsiella pneumoniae and Staphylococcus aureus at sub-inhibitory concentrations.

Biofilm formation by the pathogenic bacteria generates a serious threat to the public health as it can increase the virulence potential, resistance to drugs, and escape from the host immune response mechanisms. Among the environmental factors that influence the biofilm formation, there are only limited reports available on the role of antimicrobial agents. During the antimicrobial drug administration or application for any purpose, the microbial population can expect to get exposed to the sub-minimum inhibitory concentration (sub-MIC) of the drug which will have an unprecedented impact on microbial responses. Hence, the study has been conducted to investigate the effects of sub-MIC levels of zinc oxide nanoparticles (ZnO NPs) on the biofilm formation of Klebsiella pneumoniae and Staphylococcus aureus. Here, the selected bacteria were primarily screened for the biofilm formation by using the Congo red agar method, and their susceptibility to ZnO NPs was also evaluated. Quantitative difference in biofilm formation by the selected organisms in the presence of ZnO NPs at the sub-MIC level was further carried out by using the microtiter plate-crystal violet assay. Further, the samples were subjected to atomic force microscopy (AFM) analysis to evaluate the properties and pattern of the biofilm modulated under the experimental conditions used. From these, the organisms treated with sub-MIC levels of ZnO NPs were found to have enhanced biofilm formation when compared with the untreated sample. Also, no microbial growth could be observed for the samples treated with the minimum inhibitory concentration (MIC) of ZnO NPs. The results observed in the study provide key insights into the impact of nanomaterials on clinically important microorganisms which demands critical thinking on the antimicrobial use of nanomaterials.