title: Inactivation of Escherichia coli O157:H7 and Aerobic Microorganisms in Romaine Lettuce Packaged in a Commercial Polyethylene Terephthalate Container Using Atmospheric Cold Plasma.
abstract: The effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7 and aerobic microorganisms in romaine lettuce packaged in a conventional commercial plastic container were evaluated during storage at 4°C for 7 days. Effects investigated included the color, carbon dioxide (CO2) generation, weight loss, and surface morphology of the lettuce during storage. Romaine lettuce pieces, with or without inoculation with a cocktail of three strains of E. coli O157:H7 (~6 log CFU/g of lettuce), were packaged in a polyethylene terephthalate commercial clamshell container and treated at 34.8 kV at 1.1 kHz for 5 min by using a DACP treatment system equipped with a pin-type high-voltage electrode. Romaine lettuce samples were analyzed for inactivation of E. coli O157:H7, total mesophilic aerobes, and yeasts and molds, color, CO2generation, weight loss, and surface morphology during storage at 4°C for 7 days. The DACP treatment reduced the initial counts of E. coli O157:H7 and total aerobic microorganisms by ~1 log CFU/g, with negligible temperature change from 24.5 ± 1.4°C to 26.6 ± 1.7°C. The reductions in the numbers of E. coli O157:H7, total mesophilic aerobes, and yeasts and molds during storage were 0.8 to 1.5, 0.7 to 1.9, and 0.9 to 1.7 log CFU/g, respectively. DACP treatment, however, did not significantly affect the color, CO2generation, weight, and surface morphology of lettuce during storage (P > 0.05). Some mesophilic aerobic bacteria were sublethally injured by DACP treatment. The results from this study demonstrate the potential of applying DACP as a postpackaging treatment to decontaminate lettuce contained in conventional plastic packages without altering color and leaf respiration during posttreatment cold storage.
authors.affiliation: U.S. Department of Agriculture, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.|Department of Food Science and Technology, Seoul Women's University, 621 Hwarangro, Nowon-gu, Seoul 139-774, Republic of Korea.
authors.forename: Sea C
authors.initials: SC
authors.lastname: Min
authors.affiliation: U.S. Department of Agriculture, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.|Department of Food Science and Technology, Seoul Women's University, 621 Hwarangro, Nowon-gu, Seoul 139-774, Republic of Korea.
authors.forename: Si Hyeon
authors.initials: SH
authors.lastname: Roh
authors.affiliation: U.S. Department of Agriculture, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Glenn
authors.initials: G
authors.lastname: Boyd
authors.affiliation: U.S. Department of Agriculture, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Sites
authors.affiliation: U.S. Department of Agriculture, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Uknalis
authors.affiliation: U.S. Department of Agriculture, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Xuetong
authors.initials: X
authors.lastname: Fan
authors.affiliation: U.S. Department of Agriculture, Eastern Regional Research Center, 600 Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
authors.forename: Brendan A
authors.initials: BA
authors.lastname: Niemira
mesh_terms: D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000187:drug effects*; D005516:Food Microbiology; D018545:Lactuca / Q000382:microbiology*; D058626:Plasma Gases; D011093:Polyethylene Terephthalates
chemical_list: D058626:Plasma Gases; D011093:Polyethylene Terephthalates
keywords: Cold plasma; Dielectric barrier discharge; Escherichia coli O157:H7; Lettuce; Nonthermal processing