Survival of Listeria monocytogenes and Salmonella Enteritidis in sea bream (Sparus aurata) fillets packaged under enriched CO₂ modified atmospheres.

摘要

The effect of packaging of fresh sea bream fillets under different modified atmospheres (high levels of CO₂ combined with N₂) on the behaviour of Listeria monocytogenes and Salmonella Enteritidis was studied. Two different strains of each pathogen were spread over the sea bream fillets stored at either 0 degrees C or 4 degrees C for 16 days under standard supermarket lighting conditions (14 h a day). The atmospheres investigated were 60% CO₂/40% N₂, 70% CO₂/30% N₂, 80% CO₂/20% N₂ and air as control. Mesophilic, psychrotrophic and Enterobacteriaceae microbial counts were also performed in control batches. The results indicate that all the CO₂ concentrations used favoured the control of pathogen bacteria inoculated, when compared with air conditions especially, when combined with storage at 0 degrees C. Both storage temperature (0 degrees C and 4 degrees C) resulted in a decrease in Salmonella count. The results were more significant for Listeria strains, because during the storage at 4 degrees C Listeria count increased in all batches, while for samples stored at 0 degrees C a significant reduction in microbial load except in control batch was observed. Sensitivity differences of inoculated strains against temperature and CO₂ concentrations were also discussed