Preparation and characterization of konjac glucomannan/corn starch composite film containing bacteriocin garviecin LG34 as a novel antimicrobial packaging film

A novel antimicrobial packaging film containing konjac glucomannan, corn starch, and garviecin LG34 was prepared and its mechanical, physical, and antibacterial properties were investigated. Fourier transform infrared (FT-IR) spectra indicated that an interaction was produced between the functional groups in konjac glucomannan or corn starch and groups in garviecin LG34. The X-ray diffraction (XRD) patterns showed that the incorporation of garviecin LG34 made the network more orderly and decreased crystallinity. SEM analysis showed that garviecin LG34 significantly improved the surface state and made the surface flatter and smoother. The crystallinity decreased due to disruption of ordered starch domains caused by intermolecular interactions, and FTIR suggested possible intermolecular interactions, likely hydrogen bonding. Incorporation of garviecin LG34 significantly improved the thermal stability of composite film, and the T 10 % and the residual weight at 600 °C respectively increased by 38.23 % and 205.13 % when 6 % garviecin LG34 was added. The increase in heat stability suggested garviecin LG34, which could be inserted into the film structure, may serve as a mass tranfer barrier or thermal insulator in the composite film. When the addition amount of garviecin LG34 was increased from 0 % to 6 %, the breaking elongation, swelling degree and water solubility decreased by 16.65 %, 26.22 % and 28.71 %, and the tensile strength increased by 49.42 %. The konjac glucomannan/corn starch composite film containing garviecin LG34 not only inhibited gram-positive foodborne pathogenic Staphylococcus aureus but also Gram-negative Salmonella typhimurium . The konjac glucomannan, corn starch, and garviecin LG34 composite film can served as a novel broad spectrum antimicrobial packaging material cantainning natural antimicrobial peptide and safty for application in the food industry.