Survey of retail smoked fish with particular reference to the presence of Listeria monocytogenes
- Project start date: 1 October 2006
- Project status: Completed
- Project type: Food safety
- Discipline: Microbiology and food hygiene
- Principal researcher/s: Dr Jeff Banks, Food Safety Assurance, North Littleton, UK
- Collaborator/s: Single supplier
Research objective
The objective of this study was to assess the prevalence of Listeria monocytogenes in ready-to-eat (RTE) retail smoked fish products in Ireland. Specifically, the research aimed to determine the contamination levels of both hot and cold smoked fish by Listeria spp., with a focus on identifying the presence of Listeria monocytogenes, and to evaluate the general microbial quality of these products.
Research report
- Title: Unpublished report
- Summary: This study examined the presence of Listeria monocytogenes in ready-to-eat (RTE) smoked fish purchased from retail outlets across the Republic of Ireland. Both hot and cold smoked fish samples were analysed to determine the prevalence of Listeria spp. and specifically Listeria monocytogenes. A total of 256 samples were tested. In addition to Listeria, the study also checked for Salmonella, E. coli, Staphylococcus aureus, and Enterobacteriaceae.
- Findings:
- Overall contamination by Listeria spp. was 10.2%, with all levels deemed acceptable.
- Listeria monocytogenes was detected in 4.7% of samples at levels below 10 cfu/g.
- Cold smoked fish had a higher prevalence of Listeria, with 18.1% of 105 samples testing positive; nine of these were Listeria monocytogenes.
- Hot smoked fish had seven out of 151 samples contaminated with Listeria, including two cases of Listeria monocytogenes.
- Salmon was the most frequently contaminated with Listeria spp., showing 22 positive isolations, including 10 Listeria monocytogenes.
- Mackerel had three positive Listeria isolations, two of which were Listeria monocytogenes.
- Trout showed the lowest prevalence of Listeria spp.
- No Salmonella or E. coli were found in any of the samples.
- Nine samples contained Staphylococcus aureus.
- Enterobacteriaceae were detected in only two samples.
