Potential of Atmospheric Cold Plasma for Biofilm Control in Food Processing

The microbiological challenges presenting on foods and related contact surfaces include microbial spores and biofilms. Biofilms are three-dimensional communities of microorganisms attached to a surface, shielded inside an extracellular matrix that represent a common mode of microbial growth in industrial settings. Biofilms are problematic in a wide range of food industries. Biofilms formed on food contact surfaces are resistant to many disinfectants; particularly in biofilm formations comprised of mixed species rather than a single culture. Spores are another common and highly resistant form of bacterial contamination, which can form part of a biofilm community. The elimination of these inherently resistant microbial forms is a major challenge. Cold plasma has rapidly evolved as a technology for biological applications, such as microbial decontamination, wound healing, and cancer treatment, owing to the chemical and bio-active radicals generated, known as reactive oxygen species (ROS) and reactive nitrogen species (RNS). The action of ROS/RNS can inactivate microorganisms present within a biofilm, degrade the biochemical structure of the biofilm EPS construct, inactivate virulence factors, and can interfere with quorum sensing. Reactive species generated in liquids subjected to plasma exposure act as mediators for reactions with biological or chemical targets. These solutions retain their activity after plasma exposure and are of interest as novel decontamination agents in their own right. Boehm et al. proved that plasma activated water had a higher potency than the corresponding H₂O₂ control in both mammalian and microbial systems. This suggests that other plasma generated species are also important for the observed effects. The potential for enhanced mediation of effect through water and the containable nature of plasma species provides opportunities to apply this technology, widely, in the food environment. This presentation will outline some means of cold plasma decontamination, the key mechanisms of action, and interactions with biofilms pertinent to food safety and processing.