Quantitative microbiological risk assessment as a tool to obtain useful information for risk managers - specific application to Listeria monocytogenes and ready-to-eat meat products

The presence of Listeria monocytogenes in a sliced cooked, cured ham-like meat product was quantitatively assessed. Sliced cooked, cured meat products are considered as high risk products. These ready-to-eat, RTE, products (no special preparation, e.g. thermal treatment, before eating is required), support growth of pathogens (high initial pH = 6.2–6.4 and water activity = 0.98–0.99) and has a relatively long period of storage at chilled temperatures with a shelf life equal to 60 days based on manufacturer's instructions. Therefore, in case of post-process contamination, even with low number of cells, the microorganism is able to reach unacceptable levels at the time of consumption. The aim of this study was to conduct a Quantitative Microbiological Risk Assessment (QMRA) on the risk of L. monocytogenes presence in RTE meat products. This may help risk managers to make decisions and apply control measures with ultimate objective the food safety assurance. Examples are given to illustrate the development of practical risk management strategies based on the results obtained from the QMRA model specifically developed for this pathogen/food product combinatio

Gene Transcription Patterns of pH- and Salt-Stressed Listeria monocytogenes Cells in Simulated Gastric and Pancreatic Conditions

A Listeria monocytogenes subgenomic array, targeting 54 genes involved in the adhesion, adaptation, intracellular life cycle, invasion, and regulation of the infection cycle was used to investigate the gene expression patterns of acid- and salt-stressed Listeria cells after exposure to conditions similar to those in gastric and pancreatic fluids. Three L. monocytogenes strains, one laboratory reference strain (EGDe) and two food isolates (wild strain 12 isolated from milk and wild strain 3 isolated from fermented sausage), were used during the studies. Differences in the expressed genes were observed between the gastric and pancreatic treatments and also between the serotypes. Increased transcripts were observed of the genes belonging to the adaptation and regulation group for serotype 4b (strain 12) and to the invasion and regulation group for serotype 1/2a (strain EGDe). Interestingly, no significantly differentially expressed genes were found for serotype 3c (strain 3) in most cases. The genes related to adaptation (serotype 1/2a) and to intracellular life cycle and invasion (serotype 4b) were down-regulated in order to cope with the hostile environment of the gastric and pancreatic fluids. These findings may provide experimental evidence for the dominance of serotypes 1/2a and 4b in clinical cases of listeriosis and for the sporadic occurrence of serotype 3c

Microbiological Quality of Ready-To-Eat Products and Potential Risks for Consumers in Latvia

Publisher Copyright: © 2016 by Elīna Ciekure.Ready-to-eat (RTE) foods are challenging for food business operators as they need to remain qualitative and safe for consumers. However, consumers tend to choose them more and more often because of fast and easy handling. The highest risk from RTE foods is microbiological contamination, particularly for vulnerable groups like children, elderly, and pregnant women. The aim of the research was to assess the microbiological quality of RTE meat and fish products to highlight possible risks for consumers. A total of 15 984 analyses performed on RTE meat and fish products were included in this study. It was found that RTE meat and fish product samples representative of the market in Latvia in the period 2012-2015 had high microbiological quality and only in rare cases was contamination with hygiene indicatororganisms (coliforms and Escherichia coli) and pathogens (Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and sulphite-reducing clostridia) detected. However, it is important to pay attention to customer habits of cooking and preparing RTE foods as well-thermal processing for products intended to be used cooked, use before expiration date and adequate storage rules for products, as these have important regarding microbiological risks for health.publishersversionPeer reviewe