This overall project is defined by a long-term mission, overarching research goals, and specific project objectives. The specific objectives map to the overarching goals, which encompass the foundational approaches to the problems, and the overarching goals map to the long-term mission, which articulates the unifying theme for all research described in this project. Long-term mission: To develop improved methods for the design, evaluation, and operation of processing systems that ensure the microbial safety of commercially-produced food products. Overarching goals: Improve the quality and application of microbial models (inactivation, survival, growth, or transport) for enhancing the safety of ready-to-eat products. Develop, validate, and disseminate improved methods and tools for validation of food safety processes. Quantify the uncertainty associated with scale-up of microbial models from laboratory studies to pilot- and commercial-scale application. Specific objectives: Microbial modeling: To test and disseminate standardized protocols for quantifying thermal resistance of Salmonella in/on low-moisture food products. To develop and test novel and improved mathematical models for quantifying the effect of product characteristics (e.g., water content, water activity, fat content) on the inactivation of Salmonella in/on multiple low-moisture food products (e.g., nuts, flour, and pastes) subjected to pathogen reduction processes. To quantitatively model the relative impact of product and process characteristics (e.g., air humidity and velocity) on the inactivation rate of Salmonella on the surfaces of low-moisture products or processing equipment. Process validation: Develop standardized protocols for evaluation/validation of low-moisture pasteurization technologies (e.g., mapping temperature distributions, quantifying process variability, and selecting/preparing/utilizing a non-pathogenic surrogate).Conduct an extensive battery of inoculated challenge studies with representative products treated by multiple process technologies (e.g., steam, radio-frequency, extrusion, drying, gas), including pilot-scale trials in the MSU Biosafety Level-2 Pilot Plant, to quantify process characteristics (e.g., efficacy, variability) and to establish processing "safe harbors. "Scale-up and application: Develop and evaluate improvements of key existing thermal processes previously designed to achieve quality outcomes, but not necessarily pasteurization outcomes (e.g., dryers, baking ovens, roasters), in order to enable implementation of food safety solutions, particularly for small and medium-sized processors. To continue to build a unique academic/industry/government consortium focused on strategies for scale-up, commercial implementation, and validation of improved methods for pasteurization of low-moisture food ingredients and products.
Recent outbreaks/recalls due to Salmonella in low-moisture foods, and pending Preventive Controls rules associated with the Food Safety Modernization Act (FSMA), make processing interventions an imperative to ensure the microbial safety of low-moisture food products (e.g., nuts and nut products, cereal products, spices, dried fruits, etc.). Although various technologies exist, they have achieved very limited market penetration, and none will provide a universally acceptable solution. Also, "legacy" technologies not designed as "kill steps" (e.g., drying or baking) now must be validated for this purpose. The overall goal of this project is to develop improved methods for the design, evaluation, and operation of processing systems that ensure the microbial safety of commercially-produced food products (particularly focused on low-moisture products).The project activities will include: (1) laboratory-scale studies to generate microbiological data for various combinations of key products, processes, and pathogens (particularly Salmonella), (2) development of improved mathematical models for predicting pathogen inactivation in low-moisture food products, (3) pilot-scale studies in a biosafety level-2 (BSL2) pilot plant to: (a) validate those models under commercially relevant conditions, (b) quantify process variability and model uncertainty, and (c) test process improvements to achieve food safety objectives, and (4) utilization of that information to develop and deploy tools for validating commercial pathogen reduction processes. As a result of this project, technology companies, processors, and regulators will be better equipped to evaluate, implement, and validate low-moisture food pasteurization processes, and thereby ensure microbial safety of those products.