January 2017
 A monthly series reporting to the produce industry on CPS research projects
Farm-to-fork project focuses on contact surface transfer of pathogens 
Key Take-Aways

* Project examines potential transfer of pathogens to and from cantaloupe from farm to fork

* Cantaloupe growers opened their operations so researchers could observe harvest and field packing firsthand

* Project goal is to develop best management practices to reduce potential pathogen transfer to and from surfaces

Although a handful of researchers have examined potential pathogen contamination of cantaloupe in the field, few have studied the melon in relation to potential pathogen transfer from and to contact surfaces throughout the food chain.  Dr. Laura Strawn, an assistant professor of food science and produce safety Extension specialist at Virginia Tech , is leading a project to do just that with a focus on Salmonella and Listeria monocytogenes transfer.  "We really want to hone in on the contact surfaces and take it from farm to fork," Strawn said. "There are hardly any farm-to-fork studies that use the same methodology throughout."

Assisting her are co-investigators Dr. Ben Chapman, an associate professor and food safety Extension specialist at North Carolina State University in Raleigh, N.C., and Dr. Michelle Danyluk, an associate professor of food safety and microbiology with the University of Florida in Lake Alfred.  As Chapman pointed out, the research does not duplicate work about potential cantaloupe contamination in the field. Instead it is designed to examine contact surfaces and potential pathogen transfer.  "Other entities are taking samples of the product itself. What we're really interested in is what are the contact surfaces like from a microbiological standpoint," he said.

The two-year project is just finishing up its first year, but Strawn said their goal is to develop best management practices the industry can use to significantly reduce the potential transfer of pathogens to or from surfaces cantaloupe that may contact.

Without the open-arm reception the cantaloupe industry gave the project, Strawn said her team wouldn't have been able to gain the real-world knowledge needed to make the results useful.  She and her team spent a week last summer observing cantaloupe harvest crews in Arizona and California and collecting microbial samples from various surfaces the fruit contacted during field packing. Members of harvest crews, for example, may wear gloves made of different materials ranging from rubber or nitrile to cotton-blend. They also may employ pack tables covered in materials, such as stainless steel or single-use cardboard. In addition, crews may use stainless steel knives, cotton rags to wipe melons or brushes to remove dirt - all of which were sampled.  "For them to show us and let us see what it was like in real life and ride along with harvest crews, it was just amazing," Strawn said. "I was really grateful to them to be able to trust us. We had a lot of doors opened because we were working with a group like CPS."

At the same time, Chapman is working with retail cooperators to identify surfaces that the cantaloupes may contact. So far, he has identified 17 surfaces, from the distribution center to the retail display. His work includes both whole and cut cantaloupe.  Chapman then swabs the surfaces to collect microbial samples and determine whether the organisms are transient or are part of a resident population.  "One of the things that we're investigating is whether there are certain contact surfaces that are more likely to harbor those pathogens," he said. "If there are, we can recommend specific management practices to address those cantaloupe contact surfaces."  Although only one retail cooperator has stepped forward so far, Chapman said a few others are interested in participating, which would make the results much more meaningful.  "It's always better to have more than less," he said. "If you only have one, they may be special - they may use a different surface or have different operating procedures so we're not really measuring any variability."

The next step will be to conduct laboratory experiments using pathogens. The work will look at potential transfer from inoculated cantaloupe to clean contact surfaces and transfer from inoculated surfaces to clean cantaloupe.  Depending on the organism and the source, Strawn said the risk of transfer may differ.  Once suspect surfaces are identified, Danyluk will provide expertise on sanitizers and different methods to clean contact surfaces to significantly reduce the risk of pathogen transfer. Sanitation procedures also will be validated in the laboratory.

Project abstract may be found on the Center for Produce Safety website:  
About CPS
The Center for Produce Safety (CPS) is a 501(c)(3), U.S. tax-exempt, charitable organization focused exclusively on providing the produce industry and government with open access to the actionable information needed to continually enhance the safety of produce.  
Enhancing produce safety through  research, outreach and education
For more information:
Center for Produce Safety
Phone:  530-554-9706

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