Improving the Microbiological Safety and Quality Of Fresh and Processed Produce

<p>Whenever appropriate, standard methods such as those from the Compendium of Methods for the Microbiological Examination of Foods, the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM), or other applicable sources (AOAC, USDA, etc.), will be used for the enumeration or identification of foodborne pathogens.Pathogens. Strains that have been associated with outbreaks from the commodity of interest will be used whenever possible. If not possible, other significant pathogenic strains will be selected. These strains are often available in the PIs laboratory. Validated non-pathogenic surrogate species of various microorganisms are also available for those situations where the use of such organisms may be appropriate.Inoculation. Frozen stock cultures of bacterial strains are typically stored in glycerol stock solutions at -80°C. Prior to use strains are streaked onto non-selective media supplemented with selective agents as appropriate. Inocula may be prepared from plate or broth cultures, and may or may not be washed prior to use. Appropriate carrier media will be used for inoculations at volumes, levels and methods typical for the commodity being evaluated. Methods for inoculation of food commodities will vary, as required, to best mimic standard commodity specific criteria and the specific hypothesis-based research questions being addressed.Recovery of Pathogens from Inoculated Samples. Sample sizes, buffering solutions, and maceration methods will vary depending upon commodity and experiment-specific requirements. Enumeration of bacterial pathogens following serial dilutions by standard plating techniques onto selective and non-selective media, Most Probable Number techniques or by more sophisticated molecular techniques are commonly used by project PIs. When samples fall below the limit of detection standard enrichment protocols (FDA BAM or others) will be followed.Recovery of Pathogens from Environmental and Uninoculated Food Sources. Sampling methods to recover pathogens from the environment and foods will vary depending upon the sampling scheme and source as appropriate for the experimental design of the experiment. All attempts will be made by project PIs to not only determine frequency of pathogen isolation, but also concentration of pathogens identified, as concentration is a critical variable required in risk analysis. When appropriate, concentration techniques may be used to evaluate larger than typical sample volumes/weights and enrichment techniques used to evaluate samples when low numbers of cells are present.Evaluate and model the relationship between environmental parameters and indicator/index organisms to the levels of pathogenic microorganisms. Critical to the development of risk-based approaches to food safety is the understanding of how pathogenic microorganism's presence/numbers relate to easy-to-measure physicochemical and microbial indicators. Currently employed standards throughout the food production and manufacturing sectors involve the frequent sampling for various indicator or index organisms. However, while dogma dictates that changes in indicators or indexes result in an increased risk for a product, very little published literature on this topic is available. One of the drawbacks of testing for pathogens or microbial indicators is the interval between testing and the time of result. In many instances, this time delay can range anywhere from 12 to 120 h depending on target organism(s) that are being detected. Obviously the long detection times preclude testing from being used in real time. To address these issues, we propose to evaluate and model these relationships using available and emerging technologies.Understanding prevalence and frequencies of pathogens and antimicrobial resistance within the environment, food products and food production processing, distributions and consumer systems. Also vital to the success of any risk assessment is a comprehensive perception of both concentration and distribution of risk factors, including foodborne pathogens and presence of antimicrobial resistance genes. Much of the currently available prevalence data is lacking critical concentration data, which while difficult to determine, is an essential piece of any risk assessment. These spatial patterns that exist along the farm-to-fork continuum provide insight into current relative risk of food products and production environments, and are a critical starting point against which all risk reduction attempts can be benchmarked. Statistically-sound sampling methods and sample sizes are of fundamental importance to all studies. These issues will be addressed by our plan to evaluate frequencies and concentrations of pathogens and antimicrobial-resistance genes and identify production, manufacturing, distribution or consumer management practices that improve public health by reducing these risks.Persistence, dissemination and traceability of the microorganisms and antimicrobial resistance within the environment, food products and food processing, distribution, and consumer systems. In addition to understanding relationships between indicator organisms and pathogens, and concentration/frequencies of risk factors during food production, of crucial importance is an understanding of how risk factors can vary from the time a food product is conceived to the time it is consummed by a consumer, and how typical industry or consumer practices and handling can influence these risks. While a significant amount of data exists for some commodities, others remain relatively understudied, and handling practices are continually evolving with the industry. For data that do exist, a systematic review to identify critical data gaps and extraction of data for inclusion into comprehensive risk assessments is an opportunity for PIs of this project. While the term "cross-contamination" is often used, and the principle of prevention of cross-contamination taught to all facets of the industry, data to model and understand the fundamental mechanism of cross-contamination, and elucidate novel prevention strategies are lacking.Risk Analysis. This section describes current and planned activities/methods related to the management of microbiological risks associated with foods arising from significant points along the food production and process continuum (e.g., "farm-to-fork"). Major food commodity groups are identified, along with their interaction(s) with novel intervention strategies, and food safety diagnostic technologies. The ultimate goal of these activities is to lower or reduce pathogens in foods and thus concurrently lower risks of foodborne disease. To accomplish the tasks associated with this objective, models and a risk management framework based on commodity-specific flow diagrams and inputs from the first objective will be developed. A key component of this activity will be the use of risk modeling techniques to relate levels of microbial contamination in food to the likelihood of the occurrence of foodborne outbreaks. The information developed using this approach will then be utilized to mitigate risks at specific points along the farm to fork continuum. The data developed using the risk modeling approaches will also lead to the identification of critical data gaps.Models and risk management. Predictive microbiology and quantitative microbial risk assessment (QMRA) are rapidly developing scientific disciplines that use mathematical equations, numerical data, and expert opinion to estimate the presence, survival, growth, and death of microbes in foods. These models allow for the prediction of the safety of a product, based on the entire sequence of events up to consumption. They provide a framework for identifying critical data gaps and evaluating the effectiveness of risk-reduction strategies.</p>