The objective of this cooperative research project is to determine the applicability of high-energy, cold, atmospheric pressure plasma for the inactivation and/or elimination of pathogenic microorganisms from fresh and fresh-cut produce.
Approach: Cold, atmospheric pressure plasma will be tested for antimicrobial efficacy. Using the gliding arc plasma discharge apparatus, initial studies will systematically vary the primary parameters of the CAPP system: power (150-400mA, @ 10kV), gas flow rate (40-70 cfm), exposure time (0.25-4 min.) and plasma emitter conformation (e.g. planar flow, laminar flow, turbulent vortex flow via Venturi venting, etc.). Under each parameter configuration, the efficiency of inactivation of bacteria will be determined. The standard model target will be a spot-inoculation on the surface of an ethanol-sanitized golden delicious apple. The inoculations will consist of approximately 108 cfu/cm2 of surrogates such as L. innocua and E. coli ATCC 25922. Subsequent experiments will use the pathogens L. monocytogenes, E. coli O157:H7 or Salmonella. Once the primary treatment parameters have been optimized, subsequent studies will investigate the injection of volatile liquids into the gas stream, so as to facilitate the production of more reactive chemical species within the plasma field.