Article 36 - 4 key produce safety takeaways from the 2023 Research Symposium

Article 36 - 4 key produce safety takeaways from the 2023 Research Symposium

This article originally appeared in The Packer, and is reprinted here with permission. © 2023 The Packer www.thepacker.com

by Center for Produce Safety

Key learnings are now available from the Center for Produce Safety’s Research Symposium in June.

That’s where industry, regulators, public health and other stakeholders gathered with researchers to discuss how to apply their findings. Here are four key takeaways to help enhance food safety across the fresh produce supply chain.

1) IF YOU CAN’T FIND LISTERIA, LOOK HARDER
Three European fresh-cut facilities gave CPS-funded researcher Ana Allende full access to look for listeria. Researchers employed enhanced sampling and testing, including collecting samples with sponges instead of swabs. Allende’s team found Listeria spp. and Listeria monocytogenes across Zones 1, 2 and 3. Positive samples were high in Zone 3, which should be a cleaning and sanitation high priority.

Bottom line: We know listeria can be introduced into and become established in our production environments. If your environmental monitoring program isn’t finding it, then consider dialing up your program. An aggressive “seek and destroy” strategy may be called for. Also, Allende noted it’s easier to identify contamination sources (and develop preventive controls) by swabbing before cleaning and sanitation, when surfaces are most likely to have detectable listeria.

2) CLEANING AND SANITATION TIMING IS EVERYTHING
We’ve known pathogens can persist in some dry conditions. Clemson University’s Paul Dawson found that Listeria monocytogenes and Salmonella can persist on dry packinghouse surfaces, specifically, and after the season is over. 

Bottom line: Clean and sanitize dry environments at the end of each day; don’t wait until the next day. At season’s end, rigorously clean equipment and production environments with detergents and agitation to eliminate organic residues, then sanitize surfaces to kill Listeria monocytogenes and other bacteria and prevent biofilms. Repeat this immediately before start-up the next season.

In addition, Allende and University of Georgia’s Jinru Chen noted that when cleaning and sanitation crews understand their job and its importance, their work improves measurably. Train your crews well.

3) LEARNING FROM THIS YEAR’S FLOODING
CPS moved quickly to gather produce safety learnings from California’s 2023 floods, which caused billions of dollars in damages and uprooted many lives. Ranches across flood-impacted areas opened their gates to University of Arizona’s Channah Rock.

Her team found not all flood waters are the same, nor pose the same food safety risks. For example, soil samples from fields flooded by tributaries and creeks tested positive more often for Shiga toxin-producing E. coli than fields flooded by rivers; that likely reflects the volume and force of flood waters, and surrounding land traits such as wildlife density or animal agriculture.

Unexpectedly, researchers found relatively low levels in flooded fields of fecal indicator organisms commonly used to assess safety. Pathogen die-off was fairly rapid, within 20 days after flooding. Data suggests generic E. coli may be a more consistent marker of fecal material impacts in flooded fields.

Bottom line: There is no silver bullet. Flood water is a recognized hazard to produce safety; by incorporating soil testing for indicators and pathogens in their food safety programs, growers can evaluate potential risk to their fields, and select pre-plant time and soil management options to mitigate that risk.

4) WAX COATINGS IMPACT FOOD SAFETY
University of California, Davis’ Luxin Wang and Linda Harris found that Salmonella and Listeria monocytogenes can survive — though not grow — on waxed lemons in storage. Over time, pathogen loads decreased more on stored waxed fruit than unwaxed fruit.

Bottom line: Suppliers’ practices and controls can help prevent microbial contamination of produce coatings during product handling. Packers should store and handle waxes to prevent cross-contamination, and clean and sanitize waxing equipment frequently to prevent lot-to-lot contamination.

Industry wins when we assist Center for Produce Safety projects. To become a research cooperator, contact info@centerforproducesafety.org.

Related link: View all 2023 symposium Key Learnings and access CPS’ entire research database