|MIN, SEA CHEOL - Seoul Women'S University|
|ROH, SI HYEON - Seoul Women'S University|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/10/2016
Publication Date: 7/16/2016
Citation: Niemira, B.A., Min, S., Roh, S., Boyd, G., Sites, J.E. 2016. Atmospheric cold plasma inactivation of Escherichia coli 0157:H7 and aerobic microorganisms in cold-stored romaine lettuce packaged in a commerical polyethylene terephthalate container. Meeting Abstract. Volume 1: Page 1; IFT Annual Meeting, Chicago, IL; July 16-19, 2016.
Technical Abstract: Leafy greens continue to be a significant vector for foodborne pathogens, including Escherichia coli O157:H7. Dielectric barrier discharge atmospheric cold plasma (ACP) treatment is a promising method for microbial decontamination of produce. An important aspect of this technology is the potential for antimicrobial treatment inside sealed packages. Data is lacking on the suitability of commercially available packaging for this. The objectives of this study were to (i) study the effects of externally-applied ACP treatment on the growth of E. coli O157:H7 and mesophilic aerobic microorganisms in packaged Romaine lettuce, including the determination of sublethal injury and (ii) investigate the effects of the ACP treatment on quality properties of lettuce during post-processing cold storage. Romaine lettuce, with and without inoculation with a cocktail of three strains of E. coli O157:H7 (approximately 6 log CFU/g lettuce), were packaged in a polyethylene terephthalate (PET) commercial clamshell container and treated at 47.6 kV at 1.1 kHz for 5 min using the ACP treatment system equipped with a pin-type high voltage electrode. Romaine lettuce samples were analyzed for inhibition of E. coli O157:H7, total mesophilic aerobes, and yeasts and molds, color, carbon dioxide (CO2) generation, weight loss, and surface morphology during subsequent storage at 4 degrees C for 7 d. The ACP treatment reduced the initial counts of E. coli O157:H7 and total aerobic microorganisms by approximately 1 log CFU/g with the temperature change from 24.5 +/- 1.4 to 26.6 +/- 1.7 degrees C. The reductions in the numbers of E. coli O157:H7, total mesophilic aerobes, and yeasts and molds during storage were 0.8-1.5, 0.7-1.9, and 0.9-1.7 log CFU/g, respectively. The ACP treatment, however, did not significantly affect the color, CO2 generation, weight, and surface morphology of lettuce during storage (P > 0.05). Mesophilic aerobic bacteria showed evidence of sublethal injury following the ACP treatment. The results from this study demonstrate the potential of applying ACP to decontaminate lettuce contained in a conventional plastic package. Antimicrobial effects of this prototype terminal processing step were obtained without altering color, quality, or leaf respiration during post-treatment cold storage. This work demonstrates the ability of atmospheric cold plasma to reduce E. coli O157:H7 and background microflora on lettuce packaged in a commercial container. Reductions in microbial load were obtained without inducing significant physiological stress or adversely affecting appearance. As a waterless, chemical-free process, cold plasma has demonstrated the potential to be used as a post-packaging microbial food safety process for fresh vegetables.