Microwave plasmas in food safety. A review

By integrating contemporary plasma-based technology into classical food-monitoring procedures, those procedures offer additional food-safety treatments that are advantageous under certain conditions. Plasma based techniques are feasible for surface modification, chemical degradation, and antimicrobial treatments of surfaces. For the deactivation of spoilage bacteria, they appear suitable to treat consumer goods like foodstuff or the cleaning of the production environments like conveyor belts. However, plasma techniques offer an overwhelming width on applicability and working principles. This review summarizes the contemporary state of plasma science with a focus on microwave plasma and focuses on the divisive working principles of plasma sources and the resulting differences in their production of reactive oxygen and nitrogen species (RONS). It aims to introduce into the source dependent plasma chemistry and offers an insight into the production of RONS. It explains how RONS are the educt of plasma processed air and water, which are both feasible for a direct or an indirect treatment of vulnerable treatment targets. In other words, RONS form the foundation of all cold atmospheric plasma processes that contain either plasma processed air or plasma treated water. It also summarizes possible future processes that uses microwave techniques in the field of the decontamination of foods and offers treatment schemes that can be easily incorporated into existing food-production lines. Industrial relevance: The described plasma processes in this manuscript are often about to enter industrial manufacturing processes in the field of food processing. Especially, PTW has been used in pilot-scaled experiments, which also includes an integration of a plasma source into an existing production line of leafy greens. Against that background, plasma-based decontamination techniques offer the possibility for tailor-made processes for food processing.