Antimicrobial Effects on Starch-Based Films Incorporated with Lysozymes

An antimicrobial (AM) Active Packaging can be made by incorporating and immobilizing suitable AM agents into food package matrices and applying a bio switch concept. A starch-based film was prepared and incorporated with an antimicrobial agent, i.e. lysozyme with EDTA as a chelating agent. This film was then inoculated with the bacteria Escherichia coli and Bacillus subtilis to carry out the microbial contamination study. The inhibition of both E. coli and B. subtilis by the AM film was clearly observed as a clear zone formation in the culture agar test. The film appearance showed that lysozymes could give a better inhibition to the growth of E. coli and to B. subtilis, at a satisfying inhibition rate. From the broth test, the decreased in the optical densities were found to be 65.83% and 91.30%, suggesting an effective growth inhibition of E. coli and B. subtilis, respectively. Physically, the film which was incorporated with lysozymes was found to be slightly different from the control film. Themoisture content of the film, with lysozymes, was found to be below 10.5%, as compared to the control, after 24 hours of formation in the storage at ambient temperature.