Develop process risk models for foodborne pathogens.

Predictive microbiology has played an important role in the food industry, regulatory agencies and academia. Mathematical models have been able to estimate the behavior of microorganisms throughout the food system, including production and processing environments, and at retail and consumer levels. These models predict the effects of various intrinsic and extrinsic factors that can affect the growth, survival and inactivation of both pathogenic and spoilage organisms.

USDA-ARS scientists are in the process of validating a pathogen modeling program (PMP) for foods that have potential for a relatively high risk of foodborne disease. They also are identifying foods in which the growth of pathogens significantly deviates from current predictive models. Their research program is aimed at developing predictive models for the growth of E. coli O157:H7 in ground beef, the growth of Salmonella and Campylobacter in chicken, the growth of L. monocytogenes in cured ham, and process risk models for grinding, fabrication and carcass-chilling operations for a beef processing plant.

The scientists intend to develop new mathematical models, including those that address competitive microflora, the food matrix, functions of time, temperature, pathogen density and physiology, and strain variation. They want to develop and validate process risk models for selected food process unit operations that estimate the behavior and distribution of pathogens for foods as they are being processed.

Quantitative data on the effects of selected cultural parameters on the growth, survival and virulence of foodborne pathogens will be collected in broth media and in representative foods, particularly meats, meat products and poultry. The scientists will append data into existing databases. Descriptive models will be developed from these results, and they will be incorporated into the agency's existing PMP and other risk assessment software.

The scientists are continually developing the Pathogen Modeling Program software for use by the food industry, risk assessors and microbiologists. A new version 7.0 will be released early this summer with new features. These include a new model for E. coli O157:H7 behavior in sterile raw ground beef from 5 to 47C; a model for thermal inactivation of Salmonella in beef; lag and no-lag predictions in existing growth models; a help section with frequently asked questions; and references for each model that will appear within the output screen.

The researchers publish in the scientific literature on a regular basis. They update their publications at http://www.arserrc.gov/mfs/CRIS032.htm.

Further information. Mark Tamplin, USDA-ARS Eastern Regional Research Center, Predictive Microbiology and Process Risk Models of Foodborne Pathogens Coordinator, Center of Excellence in Microbial Models and Informatics, 600 E. Mermaid Lane, Wyndmoor, PA 19038; phone: [phone]; fax: [phone]; email: [e-mail].