LONG-TERM MISSION: To develop improved methods for the design and operation of processing systems for commercially-produced food products, based on the criteria of microbial safety, processing yield, and product quality. OVERARCHING GOALS: (A) Improve the integration of microbial models into engineering models for food handling, storage, processing, and distribution and into risk models, (B) Develop, validate, and disseminate improved methods and tools for validation of food safety processes, (C) Quantify the uncertainty associated with scale-up of microbial models from laboratory studies to pilot- and commercial-scale application, and (D) Develop phenomenological models for microbial inactivation that are based on and linked to basic mechanisms of cell adaptation and inactivation. SPECIFIC OBJECTIVES (low-moisture foods): (1) To develop effective mathematical models for quantifying the effect of product water activity on the inactivation rate of Salmonella in/on multiple low-moisture food products (e.g., nuts, flour, and pastes) subjected to pathogen reduction processes (e.g., fluid-based heating, chemical sanitation, and irradiation), (2) To validate the new models via inoculated, pilot-scale challenge studies with Salmonella on representative products subjected to the various processes in a unique, Biosafety Level-2 pilot processing facility, (3) To integrate microbial survival and inactivation models into coupled heat and mass transfer models for drying, storage, and heating of low-moisture food products, (4) To develop an academic/industry/government consortium focused on strategies for commercial implementation and validation of improved methods for pasteurization of low-moisture food products. SPECIFIC OBJECTIVES (meat and poultry): (5) To modify our previously developed, path-dependent model for the effects of sub-lethal thermal history on the subsequent thermal inactivation rate of Salmonella in meat and poultry products, to reflect cellular mechanisms, (6) To develop, validate on the pilot-scale, and distribute a universal model for thermal inactivation of Salmonella in meat and poultry products, as a function of species, composition, and structure, (7) To conduct a meta-analysis of published microbial inactivation data, or order to quantify the various sources of uncertainty inherent in inactivation models, (8) To develop and validate novel models for the rate of bacterial transfer between meat and poultry products and contact surfaces, (9) To integrate a mechanistic model for bacterial transport in postmortem muscle tissue with thermal inactivation models to quantify the relative risk of pathogen survival in intact and non-intact whole muscle meat products. SPECIFIC OBJECTIVES (fresh produce): (10) To develop and validate inactivation models for microbial disinfection/inactivation processes applied to fresh produce, (11) To develop and validate a novel model for rate of bacterial transfer between fresh produce, equipment surfaces, and processing media, and (12) To develop a decision tool for technology-neutral assessments of the suitability of irradiation as a food safety intervention for various fresh produce products.