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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Food Safety and Intervention Technologies Research » Research » Publications at this Location » Publication #325356
Title: In-package inhibition of E. Coli 0157:H7 on bulk Romaine lettuce using cold plasma

Author
item Niemira, Brendan
item MIN, SEA CHEOL - Seoul Women'S University
item ROH, SI HYEON - Seoul Women'S University
item Boyd, Glenn
item Sites, Joseph

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2016
Publication Date: 7/31/2016
Citation: Niemira, B.A., Min, S., Roh, S., Boyd, G., Sites, J.E. 2016. In-package inhibition of E. Coli 0157:H7 on bulk Romaine lettuce using cold plasma. Meeting Abstract. Volume 1: Page 1, IAFP Annual Meeting, St. Louis, Missouri, 7/31 - 8/3/2016.

Interpretive Summary:

Technical Abstract: Dielectric barrier discharge atmospheric cold plasma (ACP) has been investigated as an innovative method for in-package decontamination of fresh produce. However, while data is available for treatment of single leaves, data is lacking for the effect of ACP on the microbial decontamination of bulk leafy produce in a loose stack, a normal state of leafy produce in commercial packages. The objective of this study was to evaluate the uniformity of ACP treatment applied to bulk Romaine lettuce leaves, stacked in a commercial plastic clamshell container. The process was evaluated for antimicrobial effects against inoculated E. coli O157:H7. The impact of effective treatments on the color, surface morphology, carbon dioxide (CO2) generation, and weight loss of the leaves were also determined for leaves stacked in different positions in the container. Romaine lettuce samples (approximately 3 × 7 cm, 2.0 g), washed and inoculated with E. coli O157:H7 (approximately 6 log CFU/g lettuce), were packed in a model bulk packaging configuration: three rows and 3 or 5 layers in a commercial polyethylene terephthalate (PET) clamshell container (14.8 × 12.8 × 2.7 cm). Packaged lettuce samples were treated in an ACP treatment chamber (gap distance: 3.0 cm) at 61.2 kV (1.3 A) for 10 min. Leaves were removed in order and analyzed for E. coli O157:H7 inhibition, color (Hunter Lab), and weight loss of the samples (three replications). Results were correlated with the leaf position within the bulk stack, i.e. proximal to or distal from the electrodes in this prototype. The ACP treatment reduced the number of E. coli O157:H7 in lettuce samples by 0.4 +/-0.2 - 0.8 +/- 0.2 log CFU/g lettuce, with no significant correlation to where the leaf samples were located in each stacked configuration (P > 0.05). Respiration, leaf weight, and leaf color (L*, a*, and b* values) were not significantly different (P > 0.05) for leaves from any position in the bulk stack, regardless of the number of layers. ACP is a promising method for inactivation of E. coli O157:H7 on Romaine lettuce leaves within commercial packages as a terminal processing step. Container headspace volume and orientation of lettuce with respect to discharge electrodes are key areas for further research and development for this technology.