Research looks at risks of non-conventional surfaces

While many small- and medium-scale produce packers may innovate by using non-conventional surfaces in their facilities, little is known about the potential food safety risks they pose.

Through her CPS-funded research project, Kristen Gibson, Ph.D., with the University of Arkansas System Division of Agriculture, hopes to examine microbial persistence on those surfaces as well as common sanitation practices. Her goal is to develop a set of best practices with surface material and sanitation recommendations to reduce pathogen risks.

Gibson said:

“(Packinghouse operators) want to get the product harvested, packed, and then clean and sanitize. Can we give them the resources to make it easier?”.

She and her team chose to focus on small- and medium-scale packers because they may lack the resources, such as food safety officers or expansive stainless-steel surfaces, that large-scale packers have. 

“As I’ve been working in different aspects of produce safety, cleaning and sanitizing is an area that continues to be challenging in terms of smaller growers”. 

As part of the project’s initial phase, she and her team visited 15 packing facilities throughout the country that varied widely in size. The packing facilities handled a variety of fruits and vegetables, including indoor hydroponically grown leafy greens. 

What Gibson and her team observed in the packing facilities was a mix of non-conventional surfaces, such as those that were porous or hard to clean. The team also queried the packers about their choice of sanitizers and sanitation programs. One overriding theme was these had to be easy, economical and readily available.

They also interviewed 22 Extension and produce safety educators across 18 states who worked closely with growers about their experiences and observations in packinghouses. Their responses mostly aligned with the researchers’ observations.

In the project’s second phase the researchers will determine pathogen persistence on various surfaces. They plan to inoculate coupons, or disks, of several of the non-conventional materials with multi-strain cocktails of Salmonella, Listeria, Shiga toxin-producing E. coli or viruses. As part of those lab trials, they’ll use both clean and dirty coupons to reflect post-sanitizing and pre-sanitizing conditions.

The researchers will then incubate the inoculated coupons for seven days under temperature and relative humidity conditions that simulate packinghouse environments. Periodically, they’ll remove samples to assay for pathogen die-off.

Although they’re still finalizing their protocol for sanitizer efficacy, Gibson said it likely will involve inoculating non-conventional surface material coupons with a pathogen cocktail. They will then clean them with a common sanitizer, such as isopropyl alcohol. Afterward, they will try to recover the pathogens and assay survival to determine sanitizer efficacy.

Gibson said:

“As scientists, our job is to try to provide legitimate alternates if we’re telling them not to do something. Our end goal is a guidance document with recommendations that will at least give someone some confidence with the surfaces they’re using and the push to change if that’s needed.”

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.