The Center for Produce Safety in Woodland, CA, is out with some promising findings on Listeria from CPS-funded research at Clemson University in South Carolina.

According to the CPS report, Clemson researchers have found a couple of ways to reduce the risk of Listeria in stone fruit packinghouses. The first approach is to apply “edible coatings with antimicrobial properties,” thereby reducing the Listeria monocytogenes on fruit without affecting storability, appearance or taste.

The second area of research involves “preventive sanitation” measures to eliminate Listeria monocytogenes biofilms in “critical harvest sites including difficult-to-sanitize micro-environments.” In addition to identifying such areas, the research team is also testing commonly used sanitizers to determine optimal concentrations and contact times to inactive biofilms.  

The research is focusing where in packing houses such bacteria may reside.

Both sets of research, being conducted by Kay Cooksey and Claudia Ionita with the Clemson Food, Nutrition, and Packaging Sciences Department. Cooksey’s expertise is in packaging science and food technology, while Ioinita is a microbiologist.

Among the findings of the Cooksey-Ionita research to date are:

  • Anti-microbial coating could offer risk reduction should fruit come in contact with Listeria monocytogenes.
  • Edible coating must be compatible with the antimicrobial.
  • Coating can’t affect fruit storability, appearance or taste.
  • Related project examines packinghouse micro-environments where bacteria may hide. Researchers are then testing commonly used sanitizers.
  • Collaboration with the fresh fruit industry has been essential to both projects.

The CPS-funded research at Clemson University began by looking at commercially available food-grade coatings that could act as a carrier for food-safe anti-listerials and meet storage, appearance and taste requirements. An aloe-based coating, for example, was eliminated because of its bitter taste. Allergens like whey protein also had to be ruled out.    The researchers settled on gelatin and pectin-based coatings.

Application methods were also tested. Immersion was chosen.

Other CPS-funded research making progress on controlling Listeria has recently been conducted at the University of Connecticut where the L. mono bacteria was able to survive on the surfaces of peaches and nectarines.

The latest round of CPS research funding, for a little over $2.6 million, was announced in September.

It says its awards are for research projects directed at answering critical questions in specific areas of food safety practices. The latest topics — storage, sanitation, agricultural water, co-management and risk-based field sampling.

“We are proud to announce this slate of awards led by outstanding scientists from around the globe to answer pressing research needs and advance real-world solutions,” said Dave Corsi, Vice President of Produce and Floral at Wegmans Food Markets, and Chair for the CPS Board of Directors.

“Funding for the projects comes from a combination of contributions to CPS’ Campaign for Produce Safety and state block-grant funds. We recognize the responsibility CPS has to ensure these funds are managed prudently to provide scientific tools that support fresh produce food safety programs for our customers and industry.”

And Listeria is getting a lot of attention.

“Working together with apple growers from Washington State, Michigan and Pennsylvania, our team with almost 70 years of combined experience with Listeriaand world-class expertise in apple physiology, is excited to be able to contribute to the goals of CPS,” stated Dr. Elliot Ryser, Michigan State University.

“Through our combined efforts, this 2-year project will provide answers to many important questions, including 1) How long do outbreak strains of Listeria monocytogenes persist on apples during air and controlled atmosphere storage, 2) Do different Listeria strains have different capabilities for surviving on apples, 3) Does apple waxing increase or decrease Listeria survival, 4) Does Listeria survival on apples differ according to apple variety,  growing region, and growing season, and 5) Does Listeria survival on apples differ between planktonic cells versus biofilm-derived cells?”

The awards were made possible by funds provided by the Center for Produce Safety’s Campaign Contributors, the California Department of Food and AgricultureWashington State Department of AgricultureFlorida Department of Agriculture and Consumer Services, and Texas Department of Agriculture.

2018 RFP Grant Recipients (projects will begin January 2019):