Engineering Plasma Arrays to Remove Biofilms from Food Processing Surfaces

In this standard strengthening grant application, we propose to leverage the positive results of our current USDA seed grant to develop CAP devices that could be deployed in a variety of food industries. This project will use an engineering approach to develop several device configurations to deliver sanitizing plasmas that solve common problems encountered with biofilm accumulation in industrial settings. The project has the following specific aims:Aim 1: Determine the optimal conditions and mechanisms of CAP mediated antimicrobial action. These studies will examine the role of high energy particles and reactive ion species on microbial killing and biofilm ablation (sputtering) to determine the conditions that are most efficacious for biofilm removal and decontamination on an array of surface types.Aim 2: Construct a block planar array plasma device for in line treatment of flat surfaces. In these experiments a planar array of plasma discharges will be engineered, and their anti-biofilm activity demonstrated on conveyor belt mock-ups and other industrial equipment.Aim 3: Design and implement a radial array plasma device. The device design will be optimized to deliver plasma discharges to curved surfaces such as the interior of a pipe and to demonstrate the effect of electrically biasing the target substrate on improving biofilm removal.Our seed grant sponsored work has shown that a prototype CAP device containing a single small linear plasma discharge can successfully etch away bacterial biofilms and exert antimicrobial activities against a variety of known foodborne pathogens (E. coli, Salmonella, Listeria, Pseudomonas, Staph. aureus) in biofilms grown on a variety of industrially relevant surfaces (steel, glass, plastic, rubber). Our results have shown that for all of the microbial pathogens we have examined, that we could kill >90% of microbes found in biofilms on these surfaces with a CAP exposure of less than 10 seconds. These proof-of-concept experiments lay the ground work for developing CAP arrays that can be deployed in a variety of manufacturing environments to reduce chemical cleaning requirements, thus providing a major benefit to the food industry.It is expected that this project will produce two prototype devices: one is comprised of stacked, planar plasma discharge elements to form an array over a wide area (2 x 2 cm) to treat flat food processing surfaces, and a second configuration that will deliver a radial array of plasma that could be deployed inside of fluid delivery pipes. The project will provide a training ground for numerous graduate and undergraduate students as part of an ongoing Vertically Integrated Projects interdisciplinary program. The project also strengthens the capacity of Boise State University to perform food safety research, an emerging area of study for this institution.