Effectiveness of bacteriophages incorporated in gelatine films against Staphylococcus aureus

Abstract The use of antibiotics in the food industry is declining due to the emergence of resistant bacteria. Thus, the use of bacteriophages may provide a suitable alternative, since it allows the selective elimination of microorganisms. Another issue that faces the industry is concern about the difficulty of removing petroleum-derived plastics from the environment. This problem makes the search for new food packaging materials with extended properties a necessity. In this study, edible gelatine films containing bacteriophages were produced, and the effects of increasing concentrations of bacteriophages on the light transmission, water vapour permeability, solubility and mechanical properties of the films were characterised; in addition, micrographs of transverse film sections were made and analysed. Finally, with the purpose of assessing the influence of the manner of application and the antimicrobial properties of the prepared packaging materials, pieces of cheese previously contaminated with Staphylococcus aureus were either coated by immersion in the film-forming solution or wrapped directly with gelatine films loaded with bacteriophages. According to the results obtained, the physical properties of the films remained unaltered, irrespective of the bacteriophage concentration. The pieces of cheese immersed in the film-forming solution showed higher microbial reduction than the pieces of cheese wrapped with previously dried films. Overall, the packaging materials prepared possessed concentration-dependant antimicrobial properties, but the results obtained underline the importance of the manner of application of the bacteriophages on the foodstuff in maximizing their antimicrobial properties.