Behaviour of Listeria monocytogenes and Staphylococcus aureus in sliced, vacuum-packaged raw milk cheese stored at two different temperatures and time periods

Abstract

The behaviour of Listeria monocytogenes and Staphylococcus aureus in raw milk cheese slices packaged under vacuum was evaluated. Artificially contaminated 80-day ripened cheese was portioned, vacuum packaged, and then stored for 28 days at 4 °C and for 56 days at 10 °C. Bacterial counts were obtained before vacuum packaging and then weekly during storage. At the end of ripening, the initial L. monocytogenes count was 4.46 ± 0.89 log cfu g−1; weekly bacterial counts remained substantially unchanged in the samples stored at 4 °C but decreased to 3.54 ± 1.54 log cfu g−1 in those stored at 10 °C. The initial S. aureus count before vacuum packaging was 3.60 ± 0.78 log cfu g−1; it then gradually decreased to 2.60 ± 1.32 log cfu g−1 in the samples stored at 4 °C and to about 1.9 log cfu g−1 in those stored at 10 °C.