Reducing Cross-Contamination When Produce Contacts Bins

A University of California, Davis, research team is taking a multidisciplinary approach to reduce microbial cross-contamination when produce contacts plastic totes and bins or plastic liners in bins.

Nitin Nitin, PhD, professor in food science and technology and biological and agricultural engineering at University of California, Davis, is leading the two-pronged effort that focuses on developing rechargeable antimicrobial plastic liners and novel plastic containers that reduce microbial attachment. Eventually, Dr. Nitin said, the goal is to combine the two technologies into plastic products that could both repel and reduce pathogenic and spoilage microbes. Joining him on the project (Rechargeable antimicrobial and antifouling plastics for improved cleaning and sanitation of plastic bins and totes) are co-principal investigators polymer chemist Gang Sun, PhD, and food safety microbiologist Glenn Young, PhD.

Before embarking on the research, Dr. Nitin and his group met with representatives from the Center for Produce Safety as well as several other industry representatives, including some from the apple industry.

“The input and feedback we’ve received from them has been very encouraging,” Dr. Nitin said.

The first part of their research involves developing plastic liners for bins or totes that would have antimicrobial activity and that could be recharged periodically with a bleach solution. The plastic polymers used in the liners would be designed to bind the chlorine to the surface.

“It would continue to maintain that antimicrobial activity for some period of time,” Dr. Nitin said of the liners. “Whether it’s one full day or a couple of hours, I think that needs to be determined.”

The group focused on extruded polyethylene and polypropylene materials already used by the plastic manufacturing industry. In addition, Dr. Sun met with plastic manufacturers to ensure products that look promising could be easily ramped up to large-scale production. Dr. Nitin said the group initially focused on bin liners because they are more economical to test compared to reusable plastic containers, or RPCs.

Having an antimicrobial plastic liner also would benefit produce sectors, such as the apple industry, which still rely heavily on wooden bins. “There are many examples where wooden bins are common, and they’re very difficult to sanitize,” Dr. Nitin said. “If you can develop materials that keep them relatively cleaner, that should help them.” The group has successfully completed a demonstration that showed the liners killed Listeria, their target organism, as well as other pathogens. The next step is to conduct a proof of concept.

The researchers are further along on part two of their project, which involves conducting a proof of concept on antifouling plastics that prevent Listeria surface contamination as well as formation of Listeria   biofilms. Initial testing was conducted in the laboratory, but the researchers plan to eventually field test the materials in fresh produce processing facilities. In addition to measuring the novel plastic’s effects on reducing pathogen populations, they also will examine what, if any, impact it has on produce quality after extended contact. “We believe it’s a good start to see how this works in a highly challenged environment, like bins. Then you can adapt it to other areas,” Dr. Nitin said. “Our interest is in developing this material, which could be used in other applications.”

Dr. Nitin envisions the benefits extending beyond just packers but to companies that collect, sanitize, store, and deliver RPCs to packinghouses, distributors, and retailers. “If this helps them meet their contract and improves sanitation of bins, I think they will be very interested in adopting some of this,” he said.

The researchers also have been in contact with a U.S. Army research facility interested in antimicrobial material technologies. The military facility has an extruder, which Dr. Nitin said could provide them an opportunity to determine how antimicrobial liner production could be scaled up.