Training in tools and modelling to develop risk ranking and quantitative microbial risk assessment for cheese along the Polish and Spanish food

To ensure that ready-to-eat products are safe to eat, it is important to develop new tools to prevent and control bacterial contamination. Risk assessment has been gaining popularity in recent years and provides tools with which we can develop mathematical models for robust food safety management tools for use by health authorities, consumer protection agencies and industry stakeholders This training programme was developed under the EU-FORA programme and had the goal of training a fellow in modern quantitative microbiological risk assessment (QMRA) methods through a hands-on approach within the Unit of Microbiology and Risk Assessment at Universidad Politecnica de Cartagena (UPCT). The programme involved working on a case study focused on the microbiological safety of artisanal cheese, covering every step of a QMRA, including hazard identification, exposure assessment, hazard characterisation and risk characterisation. The case study was related to listeriosis, which constitutes a significant public health concern. Ready-to-eat foods, such as artisanal cheeses, provide an ideal environment for growth <i>Listeria monocytogenes</i>. The fellow developed skills in microbiological techniques such as preparation of thermal and growth experiments, development of a protocol for preparing artisanal cheeses at laboratory scale, as well as data analysis using the R programming language through the <i>bioinactivation</i>, <i>biogrowth</i> and <i>biorisk</i> packages. Experimental findings demonstrated that thermal treatment of milk at 60°C for 9 min causes more than 6 log-reductions of <i>Listeria</i> below the detection limit, with similar kinetics in cow's and goat's milk. Conversely, storing the finished cheese at elevated temperatures (e.g. above 25°C) was shown to promote <i>Listeria</i> proliferation. This information was combined into kinetic models based on predictive microbiology, and applied in an academic exercise to evaluate the exposure of the consumer to the hazard and to estimate the illness per serving.