Understanding the Influence of Water Properties on Microbial Inactivation during Processing of Low-Moisture Foods

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A number of recent global outbreaks and recalls related to microbial pathogens in low-moisture foods (e.g., beef jerky, grain flours, ground spices, peanut butter) have resulted in increased concerns within the food industry and research community about low-moisture food safety. Bacterial pathogens such as Salmonella spp. can survive in low-moisture foods for extended periods of time. To reduce these pathogens in low-moisture foods, different processing technologies such as steam and radio-frequency heating are used in the food industry. Cold plasma is a recent advanced potential technology, currently being evaluated at research laboratories to understand its antimicrobial efficacy. Several product- and process-factors influence the efficacy of these technologies in pathogen reduction. Among these factors, the presence of water is one of the most influential. *** The overall aim of this research program is to enhance our knowledge of how product- and process-related water properties impact microbial inactivation in low-moisture foods. These include water activity (aw), glass transition temperature (Tg) and protein mobility in Salmonella cells and relative humidity of the surrounding environment during processing. The long term objective of this research program is to improve thermal and develop cold plasma treatments to enhance low-moisture food safety. The central hypothesis is that the antimicrobial efficacy of thermal and cold plasma treatments is strongly influenced by product- and process-related water properties.*** In the short term, the specific objectives are to: 1) Understand the effect of aw on antimicrobial efficacy of thermal and cold plasma treatments, 2) Elucidate the interrelationship between aw and other fundamental water-related properties, 3) Understand the influence of water properties on bacterial inactivation mechanisms during thermal and cold plasma treatments. I will develop novel “Treatment-on-a-chip” approach using engineered microchips to study the above-mentioned factors during treatments of microbial pathogens at low-moisture environments. I will consider pathogens with or without a food product to understand the interaction of food product on the rate and mechanisms of inactivation during thermal and cold plasma treatments. Outbreak-related strains and cocktails of Salmonella spp. will be used as target microorganisms. *** This research will provide an enhanced understanding of the main product- and