Effect of modified atmosphere packaging on the growth/survival of Yersinia enterocolitica and natural flora on fresh poultry sausage

Modified atmosphere packaging (MAP) is increasingly used to extend shelf-life of fresh produce. In the present work, we determine the survival and growth of Yersinia enterocolitica and aerobic mesophiles on fresh poultry sausage under MAP. Samples were divided in two lots, half inoculated with 10 cfu g of Y. enterocolitica ATCC 9610, and half uninoculated control samples. The inoculated and control samples were packaged in different CO2 concentrations and storage at 4±1°C, during 19 days. Parameters of microbial growth (lag and log phase) were determined by Baranyi and Roberts’s equation. Aerobic mesophiles counts presented similar log and lag phase in all samples, except for the ones packaged with 20% CO2. In the inoculated samples Y. enterocolitica showed negative log phase in 100% CO2, 80% CO2, and 40% CO2, 2.1 days in 20% CO2, and approximately 0.3 day in air and 100% N2. The lag phase varied from 0.9 to 12.0 days (air and 100% CO2, respectively). Results show that MAP slowed the growth of Y. enterocolitica due to the bacteriostatic effect of CO2 on the development of this pathogen in the samples, but MAP itself was not able to eliminate this pathogen.