Newswise — To knock down the advance of the pathogen Campylobacter jejuni on raw chicken, Food Safety Consortium scientists Marlene Janes at the Louisiana State University Agricultural Center and Michael Johnson at the University of Arkansas have found that a coating of an invisible edible film on the chicken's surface significantly reduces the level of contamination.
The edible film is most effective when it consists of a combination of three antimicrobial agents: two proteins " zein and nisin " and the compound EDTA, which does the lion's share of the work in killing the pathogens. EDTA (ethylene diaamine tetraacetate) is a chelating agent, which means it binds to many different metal ions and prevents them from reacting with any other chemical that might be present. It is often used to clean people's arteries of toxic metals in the bloodstream.
"Zein by itself, EDTA by itself and nisin by itself has some benefit," explained Johnson, a food science professor at the UA Division of Agriculture. "But when the three compounds are combined you have your most effective treatment at refrigerator temperatures. It's like putting multiple blockers out there in football to keep the bacteria from ever getting out."
Janes' and Johnson's experiments showed that the EDTA treatment delivered the most killing power to the cocktail. Zein on its own doesn't have much killing power, but adding zein to the mix provided the way to deliver the killing agent. "It's a food coating to give prolonged contact with the food surface," Johnson said. "We're using edible films to wrap chicken and provide a way for the delivery of antimicrobial treatments."
Raw poultry is susceptible to bacterial contamination during raw processing and this contamination can persist when such products are refrigerated at temperatures just above freezing, about 2 to 4 degrees C. Campylobacter jejuni, the leading cause of bacterial diarrhea, is a leading source of contamination in these circumstances.
Janes, who is now an assistant professor at LSU's Ag Center food science department, said individual companies that want to use the cocktail's ingredients already approved for use in other food products can receive approval to extend it to raw poultry by filing a petition with the U.S. Department of Agriculture Food Safety and Inspection Service.
"Companies are looking at this as a control measure," Janes said. "They see that it's something they can easily do."
Much of the poultry market today consists of value-added chicken that only needs to be heated in the oven. Adequate cooking will kill pathogens. Raw poultry, however, is still a popular item in kitchens. If it comes out of the refrigerator with Campylobacter jejuni on the surface, heat will kill the pathogens in the oven, but there remains the danger of cross-contamination while the uncooked product is on the counter being prepared for the oven.
"We have to beware of people being careless in the kitchen with the raw chicken," Johnson said. "They may fully cook the chicken, but did they disinfect their hands after handling the raw chicken and before making the salad or handling the rolls?" If the consumer didn't take the precautions, raw poultry that has been treated with the invisible film and EDTA would be a safer bet to help avoid foodborne illness from this pathogen.
Previous research by Janes and Johnson has found ways to use similar antimicrobial wrappers of zein and nisin to protect ready-to-eat cooked poultry from Listeria monocytogenes, a deadly pathogen for which federal regulators have declared zero tolerance.
But Listeria isn't a major threat on raw poultry as it is on ready-to-eat products. Johnson said. Listeria thrives best where it doesn't have much competition from other bacteria and it likes cold places like the refrigerator.
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