|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: 4/6/2016
Publication Date: 5/16/2016
Citation: Niemira, B.A., Min, S., Roh, S., Boyd, G., Sites, J.E., Uknalis, J. 2016. In-package inactivation of human pathogenic bacteria and viruses on leafy greens using atmospheric cold plasma as a terminal processing step. Meeting Abstract. Volume 1: Page 1, 1st International Workshop on Plasma Agriculture; May 15,2016; Camden, NJ.
Technical Abstract: Atmospheric cold plasma (ACP) treatment is a novel, promising antimicrobial method. Dieletric barrier discharge forms of ACP are of particular interest, due to their potential for in-package decontamination. The objectives of this work were to quantify ACP inactivation of E. coli O157:H7, Salmonella, L. monocytogenes, and Tulane virus (TV, a surrogate for human norovirus) inoculated on Romaine lettuce, and to evaluate combining ACP with moisture vaporization, modified atmospheric packaging (MAP), and post-treatment storage on the inhibition as methods to enhance antimicrobial efficacy. Romaine lettuce was inoculated with E. coli O157:H7, Salmonella, L. monocytogenes (approximately 6 log CFU/g lettuce), or TV (approximately 2 log PFU/g) and packaged in a petri dish (150 mm diameter) or a polyethylene pouch (152 ' 254 mm). Leaves were packaged with and without moisture vaporization inside package. For MAP studies, pouch-packaged leaves were flushed with MAP composed of O2 at 5% or 10%, with the balance being N2. Samples were treated by ACP at 47.6 kV for 5 min. Treated packages were analyzed for the inhibition of microorganisms, either immediately or following post-treatment storage for 24 h at 4 degrees C. ACP treatment inhibited E. coli O157:H7, Salmonella, L. monocytogenes, and TV by 1.1 +/- 0.4, 0.4 +/- 0.3, 1.0 +/- 0.5 CFU/g, and 1.3 +/- 0.1 PFU/g, respectively, without environment modification with moisture and gas in packages. Lettuce packaging and moisture vaporization did not significantly influence the inactivation of bacteria (P>0.05). MAP using the N2-O2 mixtures reduced the inhibition rates of E. coli O157:H7 and TV. Following storage, L. monocytogenes declined by an additional 0.4 log CFU/g, suggesting sublethal injury as a mode of action. ACP in air effectively inactivated E. coli O157:H7, Salmonella, L. monocytogenes, and TV in lettuce, with Salmonella being the least sensitive. L. monocytogenes continued to decline in post-treatment cold storage. Reduced-oxygen MAP gas composition reduced the effectiveness of ACP. Both rigid and flexible conventional plastic packages were suitable for in-package decontamination of lettuce using ACP. E. coli O157:H7, Salmonella, L. monocytogenes, and TV were effectively reduced by ACP.