Antimicrobial activity of Myrtus communis L. water-ethanol extract against meat spoilage strains of Brochothrix thermosphacta and Pseudomonas fragi in vitro and in meat

The antimicrobial activity of hydro-alcoholic ex- tract of Myrtus communis L. was investigate in vitro and in situ against different meat spoilage biotypes of Pseudomonas fragi and Brochothrix thermosphacta. Water-ethanol myrtle extract (WEME) was prepared from myrtle leaves and used to study the antimicrobial activity, Minimum Inhibitory Concentration (MIC) and Minimum Lethal Concentration (MLC). Naturally contaminated ground beef was used to evaluate in situ antibacterial activity of freeze-dried myrtle extract at different concentrations. In vitro antimicrobial activity of WEME was significantly more effective against B. thermosphacta than P. fragi strains. MIC and MLC values were in the range of 12.5–50 and 25–100 mg DM/ml, respectively, for B. thermosphacta and P. fragi strains. In situ results showed that the microbial population, except for Pseudomonas spp., decreased significantly in ground meat with added 5 % of freeze-dried myrtle extract. In con- clusion, the findings demonstrate the effectiveness of myrtle extract to control or prevent the proliferation of meat spoilage bacteria.