KEY TAKEAWAYS:
- Produce damage or defects may impact food safety risks.
- Terms used to describe produce defects appear to vary widely and will need to be standardized.
- The QMRA, or quantitative microbial risk assessment, developed in this project will examine how post-harvest produce quality and defects may affect food safety.
- The computerized model will allow users to ask “what if” questions related to quality defects and food safety risks.
Referenced CPS Research:
A Cornell University researcher is developing a computerized model to help assess potential food safety risks for produce during the “last mile” of the supply chain.
Known as a QMRA, or quantitative microbial risk assessment, the tool will examine how produce quality and defects may affect food safety, said Martin Wiedmann, Ph.D., and principal investigator.
Titled “Quantitative microbial risk assessments need to consider quality parameters to accurately predict produce food safety risk,” the project focuses on Listeria monocytogenes and enterohemorrhagic E. coli, or EHEC.
In the past, Wiedmann said physical damage or defects — such as those caused by machines, freezes or pests — were typically viewed separately from food safety risks.
“Quality is quality, safety is safety. Don't confuse the two of them,” he said was often the general sentiment. “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. Those are separate things, but I think the reality is quality defects can and may impact food safety risks.”
Importantly, his team found a wide variation in the terms handlers and processors use to describe certain damage or quality defects, such as watersoak.
“So they might use the same term to describe different things or they might use different terms to describe the same thing,” Wiedmann said. Working closely with the CPS Industry Advisory Council and their industry contacts, his team is trying to better define many quality defect descriptions, which he said may become one of the project’s unexpected benefits. Mechanical damage, for example, was fairly widely agreed upon. Some other defects appeared to fit a range of definitions, while still others remain a work in progress.
Much of the data used to develop the QMRA model was obtained through existing literature or unpublished research, but Wiedmann and his team still spent significant time conducting laboratory inoculation studies to fill in the gaps. In that work, they developed procedures to create standardized defects in finished product and then inoculated the products with the pathogens to determine how quickly they reproduced.
He and his team are currently validating the QMRA model by running its predictions, then conducting another set of inoculation experiments to determine whether the outcome was correct.
Their last objective is to run what-if scenarios with the validated QMRA to model the impact of different last-mile scenarios on produce food safety risks. It also will allow the researchers to rank risk factors tied to post-harvest defects by how they impact pathogen growth and survival on produce and the likelihood of causing foodborne illness.
“I think the QMRA will give people an idea if they have this defect, what's the magnitude of impact on food safety,” Wiedmann said.” And hopefully it will get people a little bit more committed to doing more standardized quality assessments because they can see the value of it to manage their overall supply chain for both safety and quality.”
Ultimately, he envisioned the QMRA helping industry develop big picture business strategies by examining different scenarios. For example, maybe they’re worried about introducing defects during raw product cooling and wonder if using vacuum-cooling, instead of hydro-cooling, would have a positive or negative effect on safety and quality. Running a QMRA could therefore help managers determine how cost-effective a change would be and whether it would reduce potential food safety risks.
“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,” Wiedmann said.