Quantitative risk assessment of Listeria monocytogenes in a traditional RTE product

Ready to Eat (RTE) cooked meat products are among the most consumed RTE food subcategories in the EU. They are also associated with the highest number of listeriosis cases per year. Contamination with Listeria monocytogenes may arise from post-processing and its growth is often supported by the pH and water activity of the product. L. monocytogenes may grow during refrigeration and reach unacceptable levels at the time of consumption, posing a public health risk. The aim of this study was to conduct a Quantitative Microbiological Risk Assessment (QMRA) of L. monocytogenes in a traditional Italian RTE cooked meat product. Data for the risk assessment included prevalence and concentration of the microorganism, temperature-time conditions during transport and storage, information on the growth of the microorganism and its potential for disease (dose–response). These data were obtained from laboratory analysis of product samples (n = 50), a consumer survey (n = 160), recordings of temperatures of domestic refrigerators (n = 60) and were complemented with information from the literature. The data were described with appropriate probability distributions and introduced into a previously described growth model of L. monocytogenes. Based on the above components, a probabilistic model was created to evaluate the growth of L. monocytogenes at each stage of the product pathway (retail storage, transportation and domestic storage) using Monte Carlo simulations. The model design for this pathogen/food product combination, alongside with the findings of the study are included in a separate publication (manuscript under preparation). The results may help risk managers to apply appropriate control measures to minimise the public health risk. The project contributed to further education of the fellow, especially in the use of QMRA risk analysis tools and laid the foundations for future collaborations between the fellow's home institution, the University of Crete, Greece and the University of Perugia, Italy.