Improving Process Validation Methods for Multiple Pasteurization Technologies Applied to Low-Moisture Foods

Non-Technical Summary: <BR>Salmonella contamination of low-moisture foods is an emerging and vexing food safety challenge, reflected in recent nationwide outbreaks/recalls involving dry products. Additionally, Salmonella is known to be extremely resistant to lethal treatments on low-moisture foods. However, there is an acute lack of data and tools for reliable validation of commercial pasteurization processes across low-moisture food categories. The overall goal is to reduce risk of salmonellosis associated with low-moisture foods, by giving the industry the necessary data, knowledge, and tools to ensure the effectiveness of processing interventions. The specific objectives are to: (1) Develop mathematical models quantifying the effect of water activity on Salmonella inactivation rate, for multiple pasteurization methods and product categories, (2) Validate the inactivation models via inoculated, pilot-scale challenge studies, and (3) Develop, deliver, and assess training programs targeted at professionals responsible for validating pasteurization processes for low-moisture foods. The overall plan will entail: (1) bench-scale inactivation trials with Salmonella on three classes of products (powders, large particulates, and pastes) habituated to a range of water activities and subjected to multiple intervention processes (fluid-based heating, radio frequency energy, and low-energy X-ray), (2) development of novel inactivation models, (3) pilot-scale validation trials, and (4) development, delivery, and assessment of training programs in venues selected to specifically reach professionals responsible for validating interventions for low-moisture foods, but who generally lack information and tools needed to meet this specific challenge. This multi-disciplinary project will generate, validate, and communicate process validation tools to fill a critical industry need related to pasteurization of low-moisture foods. <P> Approach: <BR> The overall plan will entail: (1) bench-scale inactivation trials with Salmonella on three classes of products (powders, large particulates, and pastes) habituated to a range of water activities and subjected to multiple intervention processes (fluid-based heating, radio frequency energy, and low-energy X-ray), (2) development of novel inactivation models, (3) pilot-scale validation trials, and (4) development, delivery, and assessment of training programs in venues selected to specifically reach professionals responsible for validating interventions for low-moisture foods, but who generally lack information and tools needed to meet this specific challenge. Recognizing that the potential combinations of Salmonella strains, low-moisture food products, and intervention technologies are limitless, deliberate choices have been made to best represent distinct and important groups of strains, products, and technologies (within the limited scope of this project). Specifically: Food products - Each of three key categories of low-moisture foods will be represented by one product previously linked to salmonellosis outbreaks: (1) large particulates - almonds, (2) powders - wheat flour, and (3) pastes - peanut butter. Salmonella strains - A total of nine different Salmonella strains will be initially evaluated separately, then as three 3-strain cocktails, one for each of the product categories above. All strains will have been isolated previously from their respective low-moisture product and will include the following - almonds: S. Enteritidis PT30 (from the almond outbreaks, previously acquired from Dr. Linda Harris at UC-Davis), S. Enteritis PT9c strain RM4635 from the 2004 almond outbreak and S. Enteritis PT30 (RM5760) from the 2006 outbreak; wheat flour: S. Give from wheat flour and two other strains to be determined; and peanut butter: S. Tennessee K4643 and K4644 associated with the 2006 - 2007 peanut butter outbreak and S. Anatum isolated from raw peanuts. Intervention technologies - Three technologies have been chosen to represent key existing or potential pasteurization processes: (1) fluid-based heating (i.e., humid air), (2) radio frequency processing, and (3) low-energy X-ray irradiation. The training portion of this project is designed with two key features: (1) It has a tightly focused aim at professionals responsible for pasteurization validations in low-moisture food sectors, and (2) It is comprised of two phases, the first utilizing the existing expertise and knowledge of the project team (workshops in existing venues), and the second (scientific symposium) integrating and incorporating the research results from this project. Assessment of the impact of the two workshops will follow the Kirkpatrick model of assessment for all four levels of outcomes: (1) reaction, (2) learning, (3) behavior, and (4) results.