Control of Food-Borne Pathogens in Pre-and Post-Harvest Environments

NON-TECHNICAL SUMMARY: Contamination of meat, poultry and produce with foodborne pathogens frequently lead to foodborne disease. The development of antimicrobial treatments can minimize their incidence. The goal of this project is to develop effective antimicrobial interventions to reduce the risk of foodborne disease.

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APPROACH: A series of laboratory experiments will be conducted to evaluate the utilization of novel antimicrobial technologies to reduce the level of foodborne pathogens in fresh vegetables. Electrochemicallly activated water (ECAW) and bacteriophages will be tested in vegetables that will be inoculated with mixtures of strains of E. coli O157:H7 and Salmonella. The type of vegetables will be lettuce, spinach and tomatoes. The vegetables will be first inoculated with different levels of pathogenic bacteria and then will be treated with different amounts of ECAW and with different strains of specific bacteriophages. The count of remaining pathogenic bacteria on the vegetables will be determined by using standard microbiological methods. The effectiveness of those treatments will be evaluated by the extent of reduction in viable bacterial count. Another set of experimental research will be carried out to determine the inhibition of Listeria monocytogenes in Hispanic cheeses. In this case a variety of generally recognized as safe (GRAS) substances will be added at different concentrations to inhibit the growth of L. monocytogenes strains added to cheese curds. The effectiveness of the combinations of antimicrobial compounds will be evaluated by determining the count of this pathogen in stored cheeses during refrigerated storage. Another approach will be to use fumaric acid solutions to kill Escherichia coli O157:H7 in water. This treatment could be used to reduce the incidence of this pathogen in cattle drinking water. Different concentrations of fumaric acid at different pH values will be prepared and its effectiveness will be determined by measuring the extent of viable cell count of pathogenic strains added to the solutions. The effect of organic matter presence on its effectiveness will also be determined. For the second objective, the growth of Listeria monocytogenes in ready to eat meats will be studied to develop baseline data for the development of safety-based shelf life models. First a selection of fastest growing strains will be completed and then the selected strains will be used to inoculate frankfurters and ham to measure growth rates at refrigeration temperatures. Standard microbiological methods will also be used to measure Listeria growth.