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

最近全球爆发了一些与低水分食品（如牛肉干、谷物面粉、磨碎的香料、花生酱）中的微生物病原体有关的疫情和召回事件，导致食品工业和研究界对低水分食品安全的关注日益增加。像沙门氏菌这样的细菌病原体可以在低湿度的食物中存活很长时间。为了减少低水分食品中的这些病原体，在食品工业中使用了不同的加工技术，如蒸汽和射频加热。冷等离子体是一项最新的有潜力的先进技术，目前正在研究实验室评估其抗菌功效。一些产品和工艺因素影响这些技术在减少病原体方面的效果。在这些因素中，水的存在是最具影响力的因素之一。本研究计划的总体目标是提高我们对产品和工艺相关的水特性如何影响低水分食品中微生物失活的认识。这些包括水活度（aw）、玻璃化转变温度（Tg）和沙门氏菌细胞中的蛋白质迁移率以及加工过程中周围环境的相对湿度。这项研究计划的长期目标是改进热等离子体处理和开发冷等离子体处理，以提高低水分食品的安全性。中心假设是，热等离子体和冷等离子体处理的抗菌效果受到产品和工艺相关的水特性的强烈影响。在短期内，具体目标是：1)了解aw对热冷等离子体处理抗菌效果的影响；2)阐明aw与其他基本水相关性质之间的相互关系；3)了解热冷等离子体处理过程中水性质对细菌灭活机制的影响。我将开发一种新的“片上处理”方法，利用工程微芯片研究低湿度环境下微生物病原体处理过程中的上述因素。我将考虑有或没有食品的病原体，以了解食品在热和冷等离子体处理期间对失活速率和机制的相互作用。与疫情有关的菌株和沙门氏菌的鸡尾酒将被用作目标微生物。这项研究将提供对主要产品和产品的更好理解

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