| To determine if non-thermal, atmospheric-pressure plasma could provide a safer, more cost-efficient, and effective alternative to current food treatment methods, this study focused on the utilization of plasma in the reduction of microorganisms on food surfaces. Gram-positive, Gram-negative, and spore-forming representatives of foodborne bacterial pathogens were selected for testing to include Escherichia coli, Staphylococcus aureus, Salmonella enterica subsp. enterica Serovar Typhimurium, Bacillus cereus, Listeria monocytogenes, and Campylobacter jejuni. Each organism was exposed to a plasma afterglow on gelatin plates. Following exposure, the gelatin plates were liquefied for dilution and quantitative plate counting. Survivor curves, in which the number of survivors per plate versus exposure time was plotted, were generated, and decimal reduction values (the time required to achieve a 90% reduction in the microbial population) were determined for each organism to serve as a parameter for comparison of the killing efficiency of the plasma source.;A second study was aimed at determining if non-thermal, atmospheric-pressure plasmas are effective in reduction of food spoilage microorganisms on the surfaces of beef and pork. Beef and pork samples were exposed to the plasma afterglow. Surviving microbial cells were recovered following various storage intervals at 4°C, and quantitative plate counts were performed to determine if the microbial load was reduced in the plasma-exposed samples as compared to untreated samples.;In the first study, reduction of Gram-negative and Gram-positive bacterial pathogens was accomplished. Sporulated Bacillus cereus was the most resistant to the effects of the plasma source utilized in this study. In the second study, no reduction in the number of microorganisms was observed on the untreated as compared to the treated meat samples. Longer exposure times and different gas mixtures should be tested to determine if non-thermal plasma is effective in reduction of spoilage organisms. |
