Modeling the Viability and Survivability of Threat Agents in Food Matrices

Dr. Mark Tamplin at the USDA-ARS Eastern Regional Research Center, Wyndmoor, PA will perform the risk assessment modeling with data developed by the USDA-FSIS Eastern Laboratory and the USDA-FSIS Microbial Outbreaks and Special Projects Laboratory, located in Athens, GA. This task involves taking the FSIS data set, and using it to formulate viability/stability models that have useful predictive value. The problem encountered involves the assessment of the likelihood that a given agent (whose identity is known) will survive in/on a given food matrix, subject to defined environmental conditions (e.g., temperature). The data sets will be fit to straightforward mathematical expressions (decay curves), from which one can extrapolate or interpolate to obtain the desired information. In addition, we will carefully analyze the data sets to determine whether we can formulate an expression for a surface model (alternatively, a series of curves) for a given agent, that will account for all of the food-matrix-dependent data for that agent. One issue, not explicitly noted above, is whether the viability/stability of a given agent is independent of the local concentration of the agent. This is possibly unlikely because higher concentrations can promote the formation of multilayer films or aggregates, and cells/molecules in the interiors of such films/aggregates would be somewhat protected from the deleterious effects of an environmental stress. These models will be delivered to the sponsor in the form of a readily accessible computer program.