Researchers Investigate Antimicrobial Light, Optimal Sanitation Protocols for Produce Packinghouse Brushes
Two ongoing research projects funded by the Center for Produce Safety (CPS) are investigating ways to improve produce packinghouse brush sanitation, including the use of antimicrobial light and choosing the best time to replace brushes.
Antimicrobial Light vs. Pathogens on Produce Brushes
The first project, led by Govindaraj Dev Kumar, Ph.D., Associate Professor in the University of Georgia’s Center for Food Safety, is examining the efficacy of different antimicrobial light wavelengths against Salmonella enterica, Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes, considering how light application conditions, wax wash, and brush material and color impact pathogen inactivation.
Dr. Kumar chose to investigate ultraviolet-C (UV-C) at 222 nanometers (nm) and antimicrobial blue light at 405 nm due to their known germicidal activity, as well as the demonstrated safety of UV-C at 222 nm for humans, and because light at both wavelengths is less damaging to plastics and other materials than other germicidal UV light.
Having already gathered data in the lab about the influence of light treatment conditions and brush factors on antimicrobial efficacy, the researchers’ next step is to validate the antimicrobial lights in cooperating commercial peach and apple packinghouses throughout summer 2026. After employees at participating packinghouses perform normal end-of-shift sanitation, and while brushes are still wet, antimicrobial lights will be turned on for eight hours.
Dr. Kumar and his team hope that his research will help industry select the right treatments and brushes for optimal microbial safety and sanitation, and believe the use of antimicrobial light for brush sanitation in produce packinghouses could be a practical additional intervention.
“Putting in a second hurdle, we think, will reduce the presence of pathogens,” he said. “It’s cost-effective and not a chemical, so it’s a residue-free antimicrobial treatment.”
Dr. Kumar is joined on the project by co-investigators Cameron Bardsley, Ph.D., Research Food Technologist with the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS); David Shapiro-Ilan, Ph.D., Research Entomologist and Lead Scientist, USDA-ARS; and Claire Murphy, Ph.D., Assistant Professor in the School of Food Science and Extension Specialist at Washington State University.
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When is the Right Time for Packinghouses to Replace Brushes?
The replacement of worn-down brushes in produce packinghouses is necessary to ensure sanitation effectiveness and minimize pathogen cross-contamination risks, but replacing brushes comes with the cost of downtime and new equipment.
In this context, Abby Snyder, Ph.D., Associate Professor of Food Science at Cornell University, is leading a study to help industry discern the right time to replace brushes based on Listeria monocytogenes harborage.
“While replacing brushes definitely reduces [pathogen] counts and eliminates Listeria harborage, it can be expensive,” Dr. Snyder said. “What we hope to do is give people a set of options that aren’t just enhanced sanitation strategies but also replacement of wearable parts that are potential Listeria harborage points.”
The project began with the identification of deterioration markers among brushes with different uses, such as washing, drying, and waxing in a collaborating packinghouse.
Co-investigator V.M. Balasubramaniam, Ph.D., formerly at Ohio State University (now at the University of Georgia), conducted laboratory trials using steam to clean and sanitize brushes at various stages of wear. Initially, the steam was more effective at sanitizing the exterior brush filaments than portions closer to the core. But when Dr. Balasubramaniam placed the brushes in a cabinet to concentrate the steam, he observed greater and more uniform sanitation results.
Moving into the study’s second half, Dr. Snyder hopes to identify markers the industry can use to determine when brush replacement may be indicated. The next step is to trial protocols with collaborating apple packinghouses and evaluate antimicrobial outcomes.
