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<OL> <LI> To determine the affect an ammonium hydroxide brine injection of meat has on viability of microrganisms (especially Salmonella Typhimurium and Escherichia coli O157:H7). <LI> To establish the most susceptible stage of growth of spinach for internalization of E. coli O157:H7, from seeds until harvest, and determine the effect of spinach variety on internalization of E. coli O157:H7. <LI> To ascertain how long generic E. coli will survive in the soil given various inoculation conditions and to determine whether or not surviving bacteria are transferred into or onto spinach plants in the field. <LI> To develop, document the proof-of-concept, and provide a laboratory demonstration of the chemical sensor technology that can simultaneous detect histamine, cadaverine and putrescene and apply this technology to the analysis of these analytes during the storage and degradation cycle of yellowfin tuna. <LI> To determine the impact of using a lactobacillus surface treatment on the quality of strip loin steaks and ground beef.
NON-TECHNICAL SUMMARY: We see the impact of food safety almost daily now in the local news. Since January 1, 2008 the United States recalled over 60 meat and poultry products equating to 150 million pounds for pathogen contamination alone. Traditionally meat and poultry have been the primary products affected by product recalls, with Escherichia coli O157:H7 in red meat representing the bulk of the pounds recalled. Unfortunately, we are now seeing the traditional pathogens of concern for red meat becoming pathogens of concern for horticulture products. Examples are the discoveries of E. coli O157:H7 in spinach and Salmonella Typhimurium in peanuts. In the past year, over 3,900 peanut containing products have been recalled as a result of a S. Typhimurium outbreak at one processing plant alone. Food Safety recalls affect the producer, processor, and consumer. In the best case scenario it is only an economic hardship that the processor and producer have to bear. In the worst case scenario it results in a company shutting its doors, people losing jobs, a tax base being lost by the community and state, and people losing their lives. Research is being conducted to find processes and technologies that will mitigate the negative impact harmful bacterial pathogens, toxins, and allergens have on our food supply. It encompasses investigations of on-farm treatments to reduce E. coli O157:H7 in both animal and fresh cut vegetable products. It seeks alternative techniques to further reduce this and other equally harmful pathogens/toxins in food products during processing. Finally, it also includes investigations into the development of rapid state-of-the art methods to detect pathogens/toxins/allergens in foods before they make it to the consumer's table.
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APPROACH: Objective 1: Beef or pork loin will be inoculated with either Salmonella Typhimurium or Escherichia coli O157:H7. Product will be injected to 110% of the initial weight using either: water; ammonium hydroxide; salt; ammonium hydroxide x salt. Samples will be enumerated. Total Ammonia will also be measured. Objective 2: Batches of soil will be inoculated with five strains of green fluorescent protein - expressing E. coli O157:H7. Three inoculation levels will be used. Spinach seeds will be sown. In addition, seeds will be soaked in the 5 strain culture and held at 4C for 24h and then sown. Uninoculated seeds will also be sown and leaf surface inoculation of plants will be done. Samples of soil and plants (once established) will be taken weekly for up to 8 weeks. Colonies from TSA will be observed under UV light and presumptive positive E. coli O157:H7 colonies will be confirmed. Samples will be analyzed by BAX-PCR. Confocal scanning laser microscopy will be used to confirm internalization. Objective 3: A non-pathogenic strain of E. coli strain will be used to inoculate test plots. Half of the plots will be supplemented with sterilized cow manure. Inoculum will be sprayed onto the surface of plots. Half of the plots will then have the inoculum incorporated into the soil by tilling. Spinach will be seeded into the plots. After inoculation and planting, soil samples will be collected weekly. Leaf samples will also be collected once the plants are established. Soil samples and leaf samples will be analyzed for E.coli. Bacterial survival and transfer rates will be correlated with solar radiation, temperature, and rainfall data. Objective 4: The project will modify the gas simulation and mixing system that delivers the target gases to the sensor array. It will also refine SMO sensing materials for the detection of histamine, cadaverine and putrescine based on response characteristics in different environmental and interferent conditions. The sensor array will then be subject to histamine, cadaverine and putrescine under different environmental conditions. The sensor array will be evaluated to representative interferent backgrounds. The signal processing and pattern recognition algorithms based on sensor array response characteristics will be optimized. Finally, performance of the sensory will be validated coupled with pattern recognition algorithms, to detect, identify, and quantitate off gassing of histamine, putrescine, and cadaverine from yellowfin tuna. Objective 5: The following samples will be evaluated to determine the impact of lactobacilli shown to have inhibitory effects on Salmonella and E. coli spp: Fat, steaks and ground beef. Samples will initially be evaluated by inoculating with a cell suspension of E. coli 0157:H7 and/or Salmonella enteritidis. Samples will be surface treated with cultures of lactobacilli shown to have inhibitory effects on Salmonella and E. coli spp. Following the surface treatment, product will be packed and placed in simulated retail display and evaluated for microbial load over time. In addition, samples will be evaluated for retail quality when samples are only treated with lactobacilli.