Dr. Tong Zhao, UGA Center for Food Safety, inoculates Salmonella onto chicken wings. Researchers discovered using a wash treatment containing levulinic acid together with sodium dodecyl sulfate was effective at killing the pathogen. Photo courtesy of PoultryTech, GTRI.

Studies have revealed that when chickens arrive at processing facilities, they generally have high populations of bacteria, which can include Campylobacter or Salmonella, in their viscera and externally on feathers and skin. During processing, such contamination will inevitably be transferred to the processing equipment, other carcasses and potentially to final products. Many of the pathogen-intervention strategies for poultry involve the use of antimicrobial chemicals in rinses or washes; however, the efficacy of most chemical intervention treatments is reduced by the presence of organic matter. More effective antimicrobial treatments are desired that are practical, cost-effective, safe to use and not neutralized by organic matter.

With funding from Georgia’s Traditional Industries Program for Food Processing, researchers with the University of Georgia’s Center for Food Safety, under the direction of Dr. Michael Doyle, recently completed the first year of a two-year study to develop an alternative chemical treatment to reduce Salmonella (in particular, Salmonella Enteritidis) contamination on poultry skin and features during production and transport while not adversely affecting animal health, growth rates or product quality.

“A major limitation of many chemical treatments used to kill harmful bacteria in animal-growing operations is the high organic load present that neutralizes their antimicrobial activity. Hence, many disinfectants like hypochlorite and ozone are not effective, so alternate treatments are needed,” explains Doyle.

According to Doyle, results obtained from the team’s first-year studies revealed that chemicals, including acetic acid, acidic calcium sulfate, lactic acid, levulinic acid and sodium dodecyl sulfate, when tested individually using concentrations that are practical, did not reduce 5 log of Salmonella Enteritidis/ml in pure culture within 20 minutes.

However, he notes, using a wash treatment containing levulinic acid together with sodium dodecyl sulfate was effective at killing the pathogen. Results showed that the combination treatment could kill more than 5 log Salmonella/ml within 15 seconds of contact time when evaluated in pure culture. Further studies with Salmonella on chicken skin revealed similar results, especially when the treatment liquid was agitated, with reductions within 2 minutes of greater than 5 logs of Salmonella on the surface of chicken skin (cm2) or in water (ml) contaminated with chicken feces.

“Levulinic acid was selected as the primary focus of this study because it can be produced at low cost and in high yield from renewable feedstock. Its safety for humans has been widely tested, and it has [generally regarded as safe] status for direct addition to food as a flavoring substance or adjunct,” explains Doyle.

“The application of levulinic acid plus sodium dodecyl sulfate as a wash solution may have commercial application because of its efficacy in killing foodborne pathogens, relatively low cost and environmentally friendly aspects,” adds Doyle.

The team next plans to evaluate treatment approaches for the wash solution, including application by pump-up foamer technology, electrostatic spraying and low-pressure aerosolizers, as well as application at scalding temperatures (50-60°C) with different agitation rates.

A patent application on antimicrobial composition and use has been submitted. Doyle says more than 40 companies, both nationally and internationally, have expressed an interest in the treatment, and the University of Georgia Research Foundation is in the process of negotiating licensing the technology. NP