Modelling Listeria monocytogenes contamination and application of the resilience concept in the soft cheese supply chain

Listeria monocytogenes remains one of the most relevant foodborne pathogens of public health concern, particularly in ready-to-eat products. This research aims to assess the impact of selected control strategies on possible contamination with L. monocytogenes at retail in a virtual soft cheese production facility. An integrated modelling approach that combines Agent-Based Modelling (ABM) and microbial growth modelling, while embedding resilience analysis was used. The resilience of the soft cheese supply chain was evaluated using a performance indicator: the proportion of products at the end of retail storage below the EU legal threshold of 100 CFU/g. The soft cheese production facility is partitioned into three critical post-pasteurization zones: Molding, Brining, and Ripening. The baseline scenario assumed sanitation every three days, representing a standard facility operation for a soft cheese processing facility in Europe. Two potential shocks to the system were considered: elevated initial contamination of L. monocytogenes in raw milk and elevated retail temperature. In addition, three control measures: pasteurization of raw milk, daily sanitation of the facility, and lower retail temperature were considered. Model results indicated that daily sanitation lowered L. monocytogenes concentrations across post-pasteurization zones, resulting in lower contamination levels at retail. A combination of pasteurizing raw milk, sanitizing the processing facility daily, and lowering the retail temperature during cheese handling provided full resilience to L. monocytogenes contamination. These findings are derived from a simulated soft cheese production facility and should be interpreted within the context of the applied modelling assumptions and scenarios. • The soft cheese supply chain is vulnerable to L. monocytogenes contamination. • Microbial growth models and ABM are combined to improve the resilience of the chain • Applying a combination of control measures is most relevant to recover after a shock