Evaluation of the Effects of Modified Atmosphere Packaging and Bacteriophages on the Control of Pathogen Growth in Cheese

This study evaluated the effects of modified atmosphere packaging (MAP) and bacteriophage treatment on the control of pathogenic Escherichia coli strains (EHEC, EPEC, ETEC) and Listeria monocytogenes in cheese stored at 4℃, 7℃, 10℃, and 15℃. Cheese inoculated with the pathogens were packaged under various MAP conditions (MAP1: 100% N₂, MAP2: 75% N₂ + 25% CO₂, MAP3: 50% N₂ + 50% CO₂, MAP4: 25% N₂ + 75% CO₂, and MAP5: 100% CO₂). Bacteriophages were applied at concentrations of 1%, 1.5%, and 2% to the surfaces (7.5 ㎠) of the cheese. At 7℃, pathogenic E. coli did not grow in cheese packaged at any MAP conditions. Cheese packaged at MAP4 conditions exhibited a trend of pathogenic E. coli die-off beginning on the 12th day of storage. Increasing CO₂ levels in the packaging significantly inhibited the growth of pathogenic E. coli and L. monocytogenes at 10℃ and 15℃. Specifically, E. coli O157:H7 growth was reduced by 70%∼ 87%, while L. monocytogenes growth was reduced by 52%∼64%. At 4℃, the growth of L. monocytogenes was not effectively controlled by either bacteriophage or MAP4 condition alone, although the population of pathogenic E. coli decreased. However, the combination of bacteriophage treatment and MAP4 condition completely eliminated L. monocytogenes growth at 4℃. This study underscores the potential synergistic effects of combining bacteriophage application with MAP to enhance the food safety of cheese, particularly at lower storage temperatures.