System Dynamics of Salmonella and Campylobacter Contamination in the Chill Tank during Broiler Processing

NON-TECHNICAL SUMMARY: The overall goal of this research is to fully characterize the ecology of the immersion chill tank in order to optimize its operation in controlling Salmonella and Campylobacter contamination in the processing of broilers. The objectives of the research are to: (1) identify the most effective sampling strategy to assess the Salmonella level of a specific bird as it flows through the processing continuum; (2) identify how Salmonella and Campylobacter contamination levels on broiler carcasses prior to entry into the chill tank, duration of exposure, pH, chlorine, turbidity, water flow rate, and temperature levels in chill tank water interact and affect contamination levels on broiler carcasses exiting the chill tank; and, (3) develop and validate system dynamics simulation models of Salmonella and Campylobacter contamination levels on broiler carcasses in the chill tank during processing. The computer models, through computer generated graphics and animation, will serve as educational aides to make the complex interactions that potentially occur in the ecology of the chill tank more understandable. It will also serve as a tool for industry personnel to assess their current management practices and provide a mechanism to evaluate the feasibility and effectiveness of new intervention strategies. The proposed research and extension project will provide new information and tools that can be used to implement more effective chill tank management practices to control Salmonella and Campylobacter under commercial conditions.

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APPROACH: The main thrust of the research component of the project is to determine the prevalence and number of Salmonella and Campylobacter organisms in carcass rinse samples collected after broilers leave the inside-outside bird washer prior to entering the chill tank and upon exit from the chill tank. In order to increase the statistical power of the study, we will first identify the most effective sampling strategy to assess the Salmonella level of a specific bird as it flows through the processing continuum. Two methods will be assessed, repeated carcass rinses of the same bird and collecting carcass rinses of adjacent birds on the processing line, to determine which method is best. After the best sampling strategy is selected, we will identify how Salmonella and Campylobacter contamination levels on broiler carcasses prior to entry into the chill tank, duration of exposure, pH, chlorine, turbidity, water flow rate, and temperature levels in chill tank water interact and affect contamination levels on broiler carcasses exiting the chill tank. Carcass rinse samples will be collected from birds prior to their entry into the chill tank and from corresponding birds after they exit the chill tank. Each carcass rinse sample will be processed for both Salmonella and Campylobacter culture and enumeration. As the broiler carcasses move through the chill tank, the conditions within the chill tank will be monitored for pH, chlorine, turbidity, water flow rate, and temperature levels through sensors and a data logging system. The time will be recorded as each carcass rinse is performed so that the chill tank water parameters can be matched temporally with carcass rinse sample collection. The collected data will be used to develop and validate system dynamics simulation models of Salmonella and Campylobacter contamination levels on broiler carcasses in the chill tank during processing. Separate models for the two pathogens will be developed using modeling software. The structure of the model, outlining the known relationships, both linear and feedback, between the model parameters, will be developed first. The status of model components will be defined through the information gleaned from the data from the second objective. Once completed, the models will be validated by external validation. The validated model will be a significant management and decision-making tool for the poultry processing industry. The results of the research and the system dynamics models will be presented to food safety directors, HACCP coordinators and quality control personnel from several states in the Southeast as part of an ongoing Food Safety Roundtable extension effort. We also anticipate presenting our findings to multiple plant managers through group meetings at the corporate level to show how the information and models can be applied at the processing plant level. Following these meetings we will travel to the processing plants to further demonstrate our findings and discuss process change.

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PROGRESS: 2006/09 TO 2007/09<BR>
The overall objective of the project is to fully characterize the ecology of the immersion chill tank in order to optimize its operation in controlling Salmonella and Campylobacter contamination in the processing of broilers. The following three objectives will be pursued in support of the overall objective: 1) identify the most effective sampling strategy to assess the Salmonella level of a specific bird as it flows through the processing continuum; 2) identify how Salmonella and Campylobacter contamination levels on broiler carcasses prior to entry into the chill tank, duration of exposure, pH, chlorine, turbidity, water flow rate, and temperature levels in chill tank water interact and affect contamination levels on broiler carcasses exiting the chill tank; and 3) develop and validate system dynamics simulation models of Salmonella and Campylobacter contamination levels on broiler carcasses in the chill tank during processing. <BR><BR>The activities of the first year of the project have primarily involved a) planning logistics, b) gathering preliminary data at the broiler processing plant level, and c) prototype equipment design, construction, and testing. In the areas of planning logistics and preliminary data collection, we have worked with the collaborating poultry companies and have made five trips to the processing plants and collected samples. The purpose of these trips was two fold. First, we wanted to determine the method for sample collection that would give us the best kappa agreement relative to the presence or absence of Salmonella. Of the three different sample collection methods we tested, adjacent carcasses, re-rinse of the same carcass, and splitting of the carcass, none have given us the level of kappa agreement we desire to have in order to use this method for the entire study. We will continue to refine these methods until we obtain the desired results. Second, in the area of equipment design, we have assembled and tested the cadre of probes and recording devices that will measure environmental and chemical conditions of the chill tank. These conditions include pH, temperature, chlorine levels (high and low), turbidity, and oxidation/reduction potential. Initial testing of the probes was successful and we are refining the configuration of the apparatus to better fit chiller and processing plant design.
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IMPACT: 2006/09 TO 2007/09<BR>
The broiler processing industry is the largest agricultural enterprise in our state, Mississippi. The ability of the poultry processors to meet federal regulations has a direct impact their continued operation and the local and state economies. The work proposed in this project will have a direct influence on the companies ability to control Salmonella in their chill tank and ultimately on their product. One issue that poultry processing companies face is the continued pressure to use new technologies or antimicrobial compounds in an effort to reduce the presence of Salmonella on their product. While safe for use in food production, many times these commercially available compounds and technologies have not been subjected to testing with the scientific rigor necessary to determine if they are in fact efficacious in the reduction or control of the organism. By carefully monitoring the conditions in the chill tank, we hope to characterize the dynamics of the chill tank and how they affect the presence or absence of Salmonella. With this information, we can then develop computer models that will allow the poultry industry to produce the conditions that will control the pathogen in their product.