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<OL> <LI> Determine the effect of temperature and relative humidity on growth and die-off of L. monocytogenes on high-density polyethylene (HDPE) and polyurethane (PU) conveyor belt surfaces used in processing plants. <LI>Assess the impact of food contact material, inoculum level, product moisture content, contact time and contact pressure on transfer coefficients for L. monocytogenes from surface-contaminated hams to HDPE and PU and vice versa. <LI>Determine a series of transfer coefficients for L. monocytogenes from inoculated HDPE and PU contact surfaces to ham and vice versa for fifteen subsequent contacts on the same surface initially contaminated with different levels of L. monocytogenes. <LI>Develop a mathematical model based on data from the previous objectives that will express and quantify transfer potentials for Listeria cross contamination within the food processing environment.
This study will focus on meat fabrication, and quantify transfer of L. monocytogenes from ham (a model meat product) to high density polyethylene (HDPE) and polyurethane (PU) - two materials used in processing surfaces and conveyor belts in meat fabrication facilities. Factors affecting Listeria transfer that will be assessed in this study include ham moisture content (0, 15 and 30% added water), the type of contact surface (HDPE and PU), contact pressure (500, 1000, 3000, 5000, 7000 Pa), contact time (15 and 60 seconds), and initial L. monocytogenes inoculum levels (103 and 106 CFU/cm2). A series of transfer coefficients generated under varying conditions will then be subjected to mathematical modeling to determine transfer potentials for Listeria cross contamination within the retail/foodservice environment with these results used to fill one of the major data gaps identified in the current 'Draft FSIS Risk Assessment for Listeria in Ready-to-Eat Meat and Poultry Products (FSIS 2003). Journal articles will be submitted summarizing the results of the study. A yearly and final report will be submitted to ARS-NPS and NAFS.