Performing Department
(N/A)
Non Technical Summary
Problematic levels of Campylobacter and Salmonella continue to be detected on processed poultry products. While current control measures have improved poultry safety, they have not significantly impacted human illness rates nor been able to respond in real-time to pathogen contamination issues. Therefore, there is an urgent need for new research to explain the fundamental way bacteria shed from, attach to, and survive on chicken during critical processing steps. Not meeting this need represents a serious problem, because without clear scientific foundations informing pathogen control, the increased demand for poultry products translates into increased potential for foodborne disease outbreaks.Addressing these concerns, our main objective is to build tools from experiments and mathematical models to predict pathogen transfer and survival dynamics during the scalding, chilling and post-chill stages. This research is significant, since it will provide the poultry industry with science-based strategies to reduce Salmonella and Campylobacter contamination levels during processing. The resulting new insight into pathogen cross-contamination will also furnish key information for public health experts seeking to characterize risk along the poultry supply chain. Finally, due to growing populations, limited resources, and the continued public health burden from Salmonellosis and Campylobacteriosis, our results will work towards providing all Americans access to safer poultry products and help ensure the USDA's continued global role at the cutting edge of food safety.
Animal Health Component
15%
Research Effort Categories
Basic
70%
Applied
15%
Developmental
15%
Goals / Objectives
Without fundamental understanding of the mechanisms dictating bacterial cross-contamination and survival, critical poultry processing steps will continue acting as persistent reservoirs of foodborne pathogens.Accordingly, there is an urgent need to develop novel strategies whichappropriate Salmonella/Campylobacter dynamics during the scalding, chilling and post-chill stages.Not meeting this need represents a serious problem because without clear scientific foundations informing pathogen control, the increased demand for poultry products translates into increased potential for foodborne disease outbreaks.Therefore, ourlong-term goalsare (i) develop optimal real-time sanitization strategies for Salmonella/Campylobacter, adjustable to processing specifications, (ii) develop data-modeling informed surveillance to improve processor compliance.Towards these goals,this proposal'smain objectiveis to constructexperimentally-validated modelsfor predicting pathogen dynamics during the scalding, chilling and post-chill stages in terms of processing specifications. The main objective will be realized via the following three aims:1. Quantify the fundamental mechanisms regulating pathogen transfer and inactivation during immersion scalding.Wehypothesize, based on preliminary lab-scale experimentsand our previous modeling work, that mathematical models for pathogen (Salmonella,Campylobacter) inactivation and transfer could be developed as functions of scald water temperature and sanitizer chemistry, which have strong predictive capacity at the commercial-scale.2. Elucidate the key mechanisms determining pathogen cross-contamination and survival during immersion and air chilling.Considering our previous modeling results, wehypothesizethat (i) mathematical forms for pathogen (e.g.,Salmonella) transfer and inactivation could be quantified from simulated processing experiments and chemical reactions/dynamical systems theory, which have predictive merit at the industrial scale; and (ii) fluid dynamics modeling guided by experiments linking air flow/ temperature/ relative humidity to bacteria shed, transport and attachment dynamics can be used to accurately map potential pathogen spread during air chilling.3. Identify the major determinants of pathogen spread and survival during the post-chill portioning/comminuted process.Based on pertinent literature and in collaboration with Mr. Glenn Mott (Advisory team), wehypothesizethat mathematically describing pathogen (Salmonella,Campylobacter) cross-contamination and survival during the cutting/ grinding processes, contact between parts prior to tray pack, as well as during the post-chill dips, will lead to models that can provide a benchmark against which the relative risk of different post-chill treatment strategies can be compared.
Project Methods
A unique feature of our project, illustrated in our methodolgy, is highlighted bythe following guiding principle:Iterative mathematical modeling development via experiments progressing from lab to pilot to commerical scale. In order to quantify fundamental mechanisms that govern pathogen shed from, attachment to, and survival on poultry carcasses during processing, as well as pathogen inactivation dynamics in shared water environments (eg. scald/chillwater), controlled experiments at the lab scale are needed. These in combination with theory from biology, chemistry and mathematics will provide keyinformation for building mathematical forms describing the aforementioned mechanisms. In order to test and potentially adjust how these models and their predictions scale with experimental scope (i.e. pilot/industrial scale), we will test and inform the developed models with data from pilot scale experiments and industrial scale data (from the literature andour advisory team).Research Objective #1: Quantify the fundamental mechanisms regulating pathogen transfer and inactivation during immersion scalding.The mechanisms of pathogen survival in scald water have not been sufficiently quantified in terms of scald water characteristic. The goal of the research proposed under Objective #1 is to determine the underlying dynamics of Salmonella and Campylobacter inactivation and carcass-to-carcass transfer via scald water. The hypothesis for this aim is that mathematical models for pathogen inactivation and transfer can be developed as functions of scald water temperature and chemistry, with strong predictive capacity at the commercial scale. We will evaluate this claim by building (i) mathematical forms for the bacterial dynamics informed by lab and pilot-scale experiments and pertinent mathematical, chemical, and biological metrics, and (ii) models to predict pathogen inactivation and cross-contamination in the context of a simulated pilot-scale scalding process as well as against commercial-scale scalding data. The rationale behind our approach is that consistent control of pathogens during scalding is not possible without fundamental understanding of such pathogen dynamics. When the proposed research for Objective #1 is completed, we expect the overall outcome to be validated models for Salmonella/ Campylobacter cross-contamination during scalding. This result is expected to have a significant impact on food safety, leading to improved decision-making for pathogen control during scalding.Research Objective #2: Elucidate the key mechanisms underlying pathogen cross-contamination and inactivation during immersion and air chilling.Recently there have been two North American industry trends regarding poultry chilling: (i) the switch from chlorine to PAA for water sanitization during immersion chilling (IC) and (ii) the increased use of air chilling (AC) in regions with limited water resources. Given the potential for water and air to mediate pathogen cross-contamination during the respective chilling processes and the limitation of studies examining the causative mechanisms for such pathogen dynamics, our goal here is to quantify Salmonella/ Campylobacter dynamics with respect to PAA kinetics during IC and Salmonella dynamics with respect to air temperature/flow configurations for AC. Our hypothesis for IC, based on our previous modeling results, is that mathematical forms for pathogen transfer and inactivation could be quantified from simulated processing experiments, which have predictive merit at the industrial scale. Similarly, our hypothesis for AC is that fluid dynamic models guided by experiments quantifying the effect of air temperature/air flow and relative humidity on shed, transport and attachment dynamics can be used to accurately map potential pathogen spread during tunnel AC.For IC, we will test our hypothesis by building mathematical forms for the aforementioned pathogen dynamics from lab and pilot-scale experiments and pertinent mathematical, chemical and biological metrics, constructing models to predict pathogen inactivation and cross-contamination during a simulated pilot chilling process as well as against industrial scale data. For AC, we will test our hypothesis by applying our experimentally-informed model predictions to contamination patterns observed in commercial studies in the literature. The rationale behind our approach is that effective control of pathogens during chilling cannot be achieved without basic understanding of such dynamics. The overall outcome from Objective #2 will be validated models for pathogen cross-contamination during chilling, which will have a significant impact on the safety of poultry products by advancing decision making for pathogen control.Research Objective #3: Identify the major determinants of pathogen spread and survival during the post-chill portioning (parts)/comminuted process.A recent study confirmed a problematic industry trend: a significant increase in Salmonella prevalence on poultry parts as compared to post-chill numbers, with cutting/ deboning processes possibly responsible for cross-contamination. While a moderate increase in prevalence moving from carcasses to parts seems logical due to various machinery involved, no detailed causal models have been developed to date quantifying pathogen cross-contamination during this process. Thus, our goal is to quantify the mechanisms of Salmonella/ Campylobacter transfer and inactivation along typical industry steps from post-chill to parts/ comminuted products. We hypothesize that detailed stochastic descriptions of pathogen transfer and survival during the cutting/ grinding processes, as well as the contact between chicken parts prior to tray pack as well as during post-chill dip treatments, will lead to models providing a benchmark against which the relative risk of different post-chill treatment strategies can be compared. In particular, using input from Mr. Glenn Mott (Gerber's Poultry), we will simulate the parts process typically used in industry by using a pilot setup in our lab to generate data from which to build and train an individual based model (IBM). Our premise will also be tested by training the developed IBMwith prevalence data in the literature, and then running in silico studies to test the efficacy of various sanitizers on poultry parts. The rationale behind our approach is that a dynamic understanding of post-chill pathogen transfer/survival rates will provide insights difficult to obtain from experiments alone. When the proposed research for this objective is successfully accomplished, we expect the overall outcome to be an experimentally informed modeling tool capable of performing contamination scenario analysis. This result is expected to significantly contribute towards poultry product safety by providing quantified guidelines for commercial level studies to improve cross-contamination control during the post-chill process.Regardingevaluation, our advisory team (poultry industry, advisory firms, public health officials from North America) willguide and advise us on industry practices, USDA established norms, and current trends in food safety practices for modernpoultry processing in North America.Also, our advisory team will ensure that our results are translatable/practical for the poultry industry, amenable for use in QMRA modeling, and formulated to improve food safety decision making. Our project success will be measured by the robustness and predictive success of our developed models for each of the scalding, chilling and post-chilll stages, indicated by publication in top, peer-reviewed journals.On the industry side, the acheivement of our long term goalswill be measured by how our results directly and indirectly influenceboth processing practice in the poultry industryand compliance measures in the policy making realm.