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Food safety practices evolve as new technology and knowledge of the pathogens that spread foodborne illnesses becomes available.

In recent years, researchers have increasingly focused efforts on biofilm and its ability to thrive in nature and in food production and processing facilities. Biofilm is formed by a pathogen — or more often, a mixture of different pathogens — that builds a protective layer using extracellular polymeric substances (EPS).

A majority of foodborne illnesses can be traced to pathogens housed in biofilms, according to food safety research. Academics and food trade associations have stepped up efforts in recent years to learn more about biofilm, which naturally fights efforts to sanitize food contact surfaces in processing and manufacturing facilities.

Recent studies have looked at products and practices to eradicate or control biofilms in different segments of the food industry, from produce to meat processing and poultry farms.

A spokesman for the U.S. Department of Agriculture’s Food Safety and Inspection Service said regulators that conduct inspections aren’t specifically hunting biofilms, but recurring pathogen finds in facilities are likely from a biofilm. Biofilm-related content at industry events, such as the International Association for Food Protection’s 2021 conference in July, is increasing. The event featured more than two dozen sessions on biofilms, covering a wide range of pathogens (listeria, E. coli, salmonella and more) and segments of the food industry (lettuce, apples, dairy products, and in processing facilities).

Researchers tackle biofilm questions
The fresh produce industry has seen a rising interest in biofilms and their role in spreading E. coli and other pathogens. The Center for Produce Safety (CPS), which formed in the wake of a deadly E. coli in outbreak in 2006 linked to spinach, is largely funded by the industry.

Research supported by the CPS includes a look at biofilms containing Listeria monocytogenes and other pathogens in stone fruit packinghouses. Data from the study will be used to build an Excel-based guide to help stone fruit facility managers implement science-based schedules for sampling and sanitation programs. Paul Dawson and Claudia Ionita of Clemson University led the study.

Another recent CPS study, with co-lead investigator Boce Zhang of the University of Massachusetts, looks at different food contact substances and their ability to resist listeria biofilm. The study was a collaboration with the USDA’s Agricultural Research Service.

“It is imperative to understand the role of biofilm on the likelihood of pathogen survival and transmission,” Zhang said in an e-mail. “Addressing biofilm challenges requires a holistic approach and novel control strategies.”

A recent study by Austin B. Featherstone and Sapna Chitlapilly Dass, researchers at Texas A&M University’s Department of Animal Science, looks at the role of biofilm in protecting SARS-CoV-2 (Coronavirus) in meat processing plants.

Using samples from meat facility drains, the researchers developed a biofilm containing a surrogate (murine hepatitis virus) and pathogens often found in meat processing plants and tested it on stainless steel, PVC and tiles. They concluded that the biofilm protects the viral particles, allowing the potential spread of the virus among employees in the facility. The study did not focus on potential spread of the coronavirus to consumers from the products from the facility, and the Food and Drug Administration and Centers for Disease and Prevention say there is no evidence that food or food packaging transmits COVID-19.

Rong Wang, a research microbiologist with the USDA’s Agricultural Research Service, has led several studies on biofilms in meat processing and packing plants. In a report published in the Journal of Food Protection in January 2019, Wang outlines factors affecting biofilm cell transfer from contact surfaces to product contamination.

“A better understanding of these events would help the industry to enhance strategies to prevent contamination and improve meat safety,” according to the abstract for the report, “Biofilms and Meat Safety: A Mini-Review.”

Sterilex tackles biofilm questions
Sterilex, which offers food and beverage manufacturers products that detect and destroy biofilms and the pathogens they protect, spent a decade working with the Environmental Protection Agency (EPA) on testing methods and research into biofilm claims, according to Lise Duran, vice president of research and development and technology at Sterilex.

In 1999, Sterilex received approval from the EPA on the first label claim that its products remove biofilm for public health micro-organisms, Duran said.

Although much more is known about biofilm since the company was incorporated, Duran said continued research is vital. Different environments affect biofilms, and “there is a lot that goes on within a biofilm” that causes them to behave differently in various environments.

Most research, she said, focuses on single-species biofilms, but biofilms usually contain multiple species of pathogens.

“There’s certainly been a lot of great research and understanding, but it isn’t all solved,” she said.

The future of biofilm detection includes biosensor technology, and researchers continue to look for ways to improve the ability to remove biofilms as a food safety problem. “What can you do to improve technology so that it is more useful across a variety of different environments and applications?” Duran said.

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