Abstract:In order to develop biodegradable gelatin-calcium caseinate composite films with anti-microbial activity, nisin solutions of different concentrations were added to gelatin-calcium caseinate and the mechanical properties, optical properties, surface topography, anti-microbial activity and preservation efficacy of nisin-gelatin-calcium caseinate composite films were analyzed. The results indicated that the interaction between gelatin and nisin resulted in various degrees of changes in the macroscopic and microscopic properties of the composite film. With increasing concentration of nisin, the thickness and elongation at break of the composite films gradually increased. The composite films containing nisin were darker in appearance and showed a decrease in the tensile strength, water solubility, and water vapor permeability. The light transmittance of the composite film was reduced, while the light-blocking properties increased gradually with increasing nisin content, as did the surface roughness observed by atomic-force microscopy (AFM). The composite film exhibited an apparent inhibitory effect on food spoilage microorganisms (especially the gram-positive bacteria). The inhibitory effect showed an increasing trend with the increase in nisin concentration. The efficacy of the composite film in meat preservation improved continuously. In summary, the nisin-gelatin-calcium caseinate composite film developed in this study has a potential application in food packing and preservation.
