Chemical additive to enhance antimicrobial efficacy of chlorine and control cross-contamination during immersion chill of broiler carcasses

Authors: SCHAMBACH, BRADLEY - Former ARS Employee; Berrang, Mark; HARRISON, MARK - University Of Georgia; Meinersmann, Richard - Rick

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2014
Publication Date: 9/1/2014
Citation: Schambach, B.T., Berrang, M.E., Harrison, M.A., Meinersmann, R.J. 2014. Chemical additive to enhance antimicrobial efficacy of chlorine and control cross-contamination during immersion chill of broiler carcasses. Journal of Food Protection. 77(9):1583-1587.

Interpretive Summary: In the U.S., most processed broiler carcasses are cooled by immersion in a common ice cold water bath commonly referred to as a chiller. An occasional highly contaminated carcass may cause cross contamination of other carcasses with Salmonella or Campylobacter by either physical contact or by contamination of shared chiller water. Traditionally, chlorine is used as an antimicrobial to control bacterial numbers in chiller water and cross contamination of carcasses. However, chlorine is subject to inactivation due to the high level of organic material in commercial broiler chill tanks. This study was undertaken to determine if a proprietary chlorine stabilizer (T-128) can enhance the effectiveness of chlorine to limit survival of Salmonella and Campylobacter. In laboratory experiments designed to simulate commercial broiler chilling, T-128, especially in combination with chlorine, showed promise to limit transfer of both Salmonella and Campylobacter from inoculated to un-inoculated chicken wings. In a second set of experiments, control of cross contamination was found to be independent of the acidic pH of the additive. In the final set of experiments, a pilot scale chill system, with conditions very close to those encountered in commercial processing, was employed to test T-128 and chlorine with whole broiler carcasses. Carcasses experimentally inoculated with Salmonella and Campylobacter were co-chilled with un-inoculated carcasses such that some were subjected to physical contact while others were only be exposed to the inocula through shared chill tank water. T-128 was shown to significantly improve the efficacy of chlorine in preventing cross contamination of all un-inoculated carcasses. These data suggest that T-128 could be successfully employed as a processing aid when used with chlorine in a commercial broiler processing plant to control cross contamination of carcasses in chiller water. These data are useful to processors, regulators and poultry scientists as they continue to strive for optimum control of bacterial cross contamination during broiler carcass immersion chilling.

Technical Abstract: Immersion chilling during broiler processing can be a site for cross contamination between the occasional highly contaminated carcass and those that are co-chilled. Chlorine is often used as a chill tank antimicrobial but it can be overcome with heavy organic loads associated with the constant supply of carcasses. A proprietary chemical chlorine stabilizer (T-128) was tested as a chill tank additive in bench and pilot scale experiments simulating commercial broiler chilling. In bench scale experiments, 0.5% T-128 was compared to plain water control, 50 ppm chlorine and the combination of 0.5% T-128 with 50 ppm chlorine to control transfer of Salmonella and Campylobacter from inoculated wings to co-chilled un-inoculated wings. T-128 treatments were noted to have a pH of less than 4.0. Both chlorine and T-128 lessened cross contamination with Salmonella (P < 0.05); T-128 and T-128 with chlorine were significantly more effective (P < 0.05) than the control or plain chlorine for control of Campylobacter. To determine if the antimicrobial effect of T-128 was due merely to a lower pH, a set of bench scale experiments were conducted. The pH of 50 ppm chlorine solution was set to approximately 3.5 with either 0.5% T-128 or by addition of H3PO4 alone (the acidic component of T-128). Both conditions were tested for ability to control cross contamination with Salmonella and Campylobacter. T-128 with 50 ppm chlorine was significantly more effective than the pH matched control in limiting transfer of both Salmonella and Campylobacter from inoculated to un-inoculated wings during simulated broiler chilling. In commercial broiler chilling, a pH of close to 6.0 is preferred to maximize chlorine effectiveness, while maintaining water holding capacity of the meat. In a set of pilot scale experiments with T-128, a near ideal pH of 6.3 was achieved by using tap water instead of the distilled water used in bench scale experiments. Pilot scale chill tanks were used to compare 0.5% T-128 with 50 ppm chlorine to plain 50 ppm chlorine for control of cross contamination between whole carcasses inoculated with Salmonella and Campylobacter and co-chilled un-inoculated carcasses. The T-128 treatment resulted in significantly less cross contamination by either direct contact or water transfer with both organisms compared to plain chlorine treatment. T-128 may have use in commercial broiler processing to enhance the effectiveness of chlorine in processing water.