Development of a Facility-level Quantitative Microbial Risk Assessment Model for Listeria monocytogenes in Cold Smoked Salmon

Introduction: Cold smoked salmon (CSS) has traditionally been challenging in regard to the development of Hazard Analysis Critical Control Point (HACCP) plans as the process lacks a definitive inactivation step. Instead control is established through various steps, each contributing to partial control of microbiological hazards. To determine if quantitative microbial risk assessment (QMRA) techniques can be used to develop risk-based HACCP plans, a manufacturing facility-level risk assessment was undertaken for Listeria monocytogenes.

Purpose: This work undertook development of a QMRA to identify key factors contributing to the risk of L. monocytogenes in CSS. The objectives were to develop a facility-specific modular product pathogen pathway risk assessment model for CSS and determine if sensitivity analysis can be used to identify risk-based critical control points (CCPs).

Methods: An extensive literature search was performed; relevant data was reviewed, including identification of appropriate predictive microbiology models describing L. monocytogenes behavior in CSS. The exposure assessment for the CSS process was based on seven modules (Primary Production, Raw Product Processing, Brining, Cold Smoked Product Processing, Post-Cold Smoking Processing, Distribution/Marketing, and Consumer). The output of the exposure assessment was then linked to the dose response module. The model was simulated using Latin Hypercube Sampling for 100,000 iterations with @Risk software.

Results: Predicted contamination levels at retail were similar to those from the published literature. The sensitivity analysis indicated slicing, the incoming concentration of L. monocytogenes in raw salmon, and cold smoking as the three main critical factors affecting the concentration of L. monocytogenes at the end of the manufacturing process.

Significance: This study provides a QMRA at a facility level that can be used to evaluate risk mitigation strategies for L. monocytogenes. This model is being used to identify CCPs and the impact of critical limits for the control of L. monocytogenes in CSS.