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Consumption of raw or insufficiently cooked mussels contaminated with hepatitis A virus (HAV) is a major cause of infection to humans. The origin of mussels commonly used for the preparation of marinated seafood salads is often unknown, since different producers worldwide undergo a precooking treatment at the original collection site with methods and parameters not always indicated. These treatments could be insufficient for the inactivation of HAV, which is characterized by a high temperature resistance. Both high hydrostatic pressure (HHP) and marinade treatments have been shown to affect HAV vitality. In this study, two treatments (HHP and marinating) were combined in order to assess a potential synergistic effect on the virus vitality. A kinetic test was conducted by subjecting the experimentally-contaminated mussels (HAV titre: 10(6)/ml TCID50) to marinating, and to different HHP treatment (4,000; 5,000; and 6,000 bar for 1, 5, and 9 min). Virus post-treatment vitality was assessed by its ability to grow on cell cultures and by quantitative real-time RT-PCR to evaluate virus resistance under such conditions. Marinating treatment alone (final pH 4.3, and NaCl 2 %) did not inactivate the virus. On the other hand, the use of HHP treatment alone on non-marinated HAV-contaminated mussels was effective only above 5,000 bar for 5 min. The results of the present study elucidate the synergistic effect of a combination between marination and HHP treatments on the inactivation of the virus.

Aims: The aim of the study was to evaluate the behaviour of Listeria monocytogenes in the conditioning liquid of packaged water buffalo mozzarella cheese (WBMC)., Methods and Results: The conditioning liquid was contaminated with L. monocytogenes, and the contaminated samples were stored at four different storage temperatures: 5 and 10 °C for 22 days; 20 °C for 9 days; 20 °C for 3 days and then at 5 °C for 6 days. The results showed that L. monocytogenes concentration decreased when contaminated samples were stored at 5 °C. When WBMC was stored at 20 °C and at 10 °C, L. monocytogenes started to grow after a lag phase of 3 and 10 days, respectively. When samples were stored at variable temperature conditions, L. monocytogenes numbers showed a lag phase of 5 days., Conclusions: Use of a conditioning liquid characterized by acidity and a correct storage temperature is able to counteract pathogen replication during shelf life. A high concentration of lactic acid bacteria was associated with effective control of L. monocytogenes but the role of lactic acid bacteria in WBMC conditioning liquid requires further investigation., Significance and Impact of the Study: According to European regulations, food producers should be able to justify decision-making on the shelf life assigned to their products, taking into account reasonable storage conditions and use by consumers. The results of the trial yielded information for producers of WBMC and similar cheeses for decision-making on product shelf life., (© 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.)