Researchers Developing Risk Assessment Model to Evaluate Food Safety Impacts of Produce Defects
Supported by the Center for Produce Safety (CPS), researchers at Cornell University are developing a quantitative microbial risk assessment (QMRA) model to evaluate how post-harvest produce quality defects may affect food safety risks, particularly during the final stages of the supply chain.
Led by Martin Wiedmann, Ph.D., D.V.M., the project, “Quantitative Microbial Risk Assessments Need to Consider Quality Parameters to Accurately Predict Produce Food Safety Risk,” focuses on the effects of produce damage and defects on the growth and survival of Listeria monocytogenes and enterohemorrhagic Escherichia coli (EHEC).
Although produce quality and food safety have traditionally been considered separate issues, Dr. Wiedmann explained that certain quality defects, including damage caused by equipment, freezing, or pests, may influence microbial food safety risks.
“If it doesn't look good, if it doesn't taste right, very broadly speaking that doesn't mean it's unsafe. Similarly, product may carry an increased food safety risk even though it looks, smells, and tastes perfectly fine,” Dr. Wiedmann said. “Those are separate things, but I think the reality is quality defects can and may impact food safety risks.”
The researchers aim to develop a computerized model that will allow produce industry stakeholders to evaluate how different post-harvest conditions and quality defects may affect pathogen growth, survival, and the likelihood of foodborne illness.
Standardizing Produce Quality Defect Definitions
An early challenge identified by the researchers was the lack of standardized terminology used by produce handlers and processors to describe quality defects.
According to Dr. Wiedmann, industry stakeholders often used the same terms to describe different defects, or different terms to describe the same defect. For example, definitions of "watersoak" and other quality issues varied across industry.
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Working with the CPS Industry Advisory Council and industry contacts, the research team has sought to establish more consistent definitions for common produce defects.
Although certain defects, such as mechanical damage, were relatively consistently defined, others had multiple interpretations or required further clarification.
Standardizing defect terminology may represent an additional benefit of the research, potentially supporting more consistent produce quality assessments throughout the supply chain.
Developing and Validating the Quantitative Microbial Risk Assessment Model
To develop the QMRA model, the researchers drew on existing scientific literature and unpublished research, supplemented by laboratory inoculation experiments to address data gaps.
For the experiments, the team developed procedures to create standardized defects in finished produce products. The researchers then inoculated the products with L. monocytogenes and EHEC to evaluate pathogen growth under different conditions.
The researchers are validating the model by comparing its predictions with the results of additional inoculation experiments to determine how accurately it estimates microbial behavior.
Once validated, the QMRA will be used to simulate different scenarios during the final stages of the produce supply chain, allowing researchers to assess the effects of post-harvest quality defects on food safety risks.
The model will also enable the researchers to rank risk factors associated with produce defects according to their effects on pathogen growth and survival, as well as the likelihood of causing foodborne illness.
Potential Applications for Produce Industry Risk Management
Dr. Wiedmann expects the QMRA model to help produce industry stakeholders make more informed decisions about quality management, processing practices, and food safety interventions.
For example, the model could be used to compare how different cooling methods, such as vacuum-cooling and hydro-cooling, may affect produce quality and microbial food safety risks. Such assessments could help operators evaluate whether changes to processing practices would provide meaningful food safety benefits relative to their costs.
Dr. Wiedmann also suggested that the model could encourage more standardized produce quality assessments by demonstrating their potential value for managing both food safety and product quality.
Ultimately, the researchers intend for the QMRA to support evidence-based decision-making by allowing industry stakeholders to compare potential interventions and prioritize investments based on their expected effects on food safety.
“With these QMRAs, the biggest opportunity is to help people make sure they're putting their money where they get the biggest bang for their buck, because sometimes decision-making can be based on anecdotal evidence and it can be hard for people to rationally assess different alternatives,” Dr. Wiedmann said.
