|Boce Zhang, PhD University of Massachusetts, Lowell
Even if they are successful, the physical modifications and coatings also must be feasible and cost-effective, Zhang said. To that end, the researchers are working with a fresh-cut processor and a food equipment manufacturer to ensure the results are applicable to the produce industry.
Biofilms have become the focus of more research recently because of their resistance to sanitizer treatments. Communities of microorganisms secrete glue-like substances, allowing them to adhere to surfaces. Not only does this film reduce the organisms' chances of being displaced but it also offers protection from some antimicrobials.
Nearly one year into the two-year project, Zhang said they have screened about 20 FCS coatings for efficacy against Listeria monocytogenes biofilm formation. To be candidates, the materials had to already be vetted and registered by the FDA for use in the food supply chain.
Fortunately, he said, many already are used by other parts of the food industry, such as meat and poultry processors. But they hadn't been screened for performance in a produce facility.
From there, the top two to three performers will be selected for more in-depth studies.
Zhang and his group also are examining whether physical changes, such as etching of a material's surface, could reduce biofilm formation. The practice, commonly used on submerged ship hulls, creates a super-hydrophobic coating. Essentially, a thin layer of air bubbles protects the surface and prevents pathogens from attaching.
Zhang and his team will then assess whether applying an FDA-registered FCS coating to physically modified material surfaces further enhances non-fouling properties. This is where input from the cooperating food equipment manufacturer and coating suppliers will be invaluable.
"When they apply coatings, there are different ways to apply them," Zhang said. "And there are different materials that are more easily applied on a flat surface or a complex surface. These are some of the issues where we'll need their input."
Although this project focuses on Listeria biofilm formation, Zhang said treated test materials will be subjected to cocktails that also contain E. coli O157:H7, Pseudomonas fluorescens and/or Ralstonia insidiosa. The latter two organisms have been identified as top biofilm formers among microorganisms associated with leafy greens.