In-package atmospheric cold plasma treatment of bulk grape tomatoes for microbiological safety and preservation

Min, Sea C.,Roh, Si Hyeon,Niemira, Brendan A.,Boyd, Glenn,Sites, Joseph E.,Fan, Xuetong,Sokorai, Kimberly,Jin, Tony Z. Elsevier 2018 Food Research International Vol.108 No.-

<P><B>Abstract</B></P> <P>Effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of <I>Salmonella</I> and the storability of grape tomato were investigated. Grape tomatoes, with or without inoculation with <I>Salmonella</I>, were packaged in a polyethylene terephthalate (PET) commercial clamshell container and cold plasma-treated at 35 kV at 1.1 A for 3 min using a DACP system equipped with a pin-type high-voltage electrode. DACP treatment inactivated <I>Salmonella</I> (<I>p</I> < 0.05) without altering the color or firmness of the grape tomatoes (<I>p</I> > 0.05). DACP treatment inactivated <I>Salmonella</I> uniformly in both layers of the double-layer configuration of the grape tomatoes regardless of the position of the tomatoes in each layer. <I>Salmonella</I> was most efficiently inactivated when the headspace to tomato volume ratio of the container was highest. Integration of rolling of tomatoes during treatment significantly increased the <I>Salmonella</I> reduction rates from 0.9 ± 0.2 log CFU/tomato to 3.3 ± 0.5 log CFU/tomato in the double-layer configuration of the tomato samples. Rolling-integrated DACP also initially reduced the number of total mesophilic aerobic bacteria and yeast and molds in the double-layer configuration of tomato samples by 1.3 ± 0.3 and 1.5 ± 0.2 log CFU/tomato, respectively. DACP treatment effectively reduced the growth of <I>Salmonella</I> and indigenous microorganisms at 10 and 25 °C, and did not influence the surface color, firmness, weight loss, lycopene concentration and residual ascorbic acid of grape tomatoes during storage at 10 and 25 °C. DACP treatment holds promise as a post-packaging process for improving microbial safety against <I>Salmonella</I> and storability of fresh grape tomatoes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Atmospheric cold plasma treatment (ACPT) inactivates <I>Salmonella</I> on grape tomatoes. </LI> <LI> A higher container headspace to tomato volume ratio results in higher inactivation. </LI> <LI> Inactivation is uniform with tomatoes in a 2-layer configuration in the container. </LI> <LI> Rolling of samples during ACPT increases <I>Salmonella</I> reduction rates. </LI> <LI> ACPT inhibits microbial growth during storage without affecting quality. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

In-package inhibition of <i>E. coli</i> O157:H7 on bulk Romaine lettuce using cold plasma

Min, Sea C.,Roh, Si Hyeon,Niemira, Brendan A.,Boyd, Glenn,Sites, Joseph E.,Uknalis, Joseph,Fan, Xuetong Elsevier 2017 Food microbiology Vol.65 No.-

<P><B>Abstract</B></P> <P>Dielectric barrier discharge atmospheric cold plasma (DACP) treatment was evaluated for the inactivation of <I>Escherichia coli</I> O157:H7, surface morphology, color, carbon dioxide generation, and weight loss of bulk Romaine lettuce in a commercial plastic clamshell container. The lettuce samples were packed in a model bulk packaging configuration (three rows with either 1, 3, 5, or 7 layers) in the container and treated by DACP (42.6 kV, 10 min). DACP treatment reduced the number of <I>E. coli</I> O157:H7 in the leaf samples in the 1-, 3-, and 5-layer configurations by 0.4–0.8 log CFU/g lettuce, with no significant correlation to the sample location (<I>P</I> > 0.05). In the largest bulk stacking with 7 layers, a greater degree of reduction (1.1 log CFU/g lettuce) was observed at the top layer, but shaking the container increased the uniformity of the inhibition. DACP did not significantly change the surface morphology, color, respiration rate, or weight loss of the samples, nor did these properties differ significantly according to their location in the bulk stack. DACP treatment inhibited <I>E. coli</I> O157:H7 on bulk lettuce in clamshell containers in a uniform manner, without affecting the physical and biological properties and thus holds promise as a post-packaging process for fresh and fresh-cut fruits and vegetables.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dielectric barrier atmospheric cold plasma (DACP) was applied to <I>E. coli</I> O157:H7. </LI> <LI> DACP inhibited <I>E. coli</I> O157:H7 on bulk lettuce layered in a commercial container. </LI> <LI> DACP uniformly inhibited the pathogen on 3- and 5-layer cut lettuce. </LI> <LI> Shaking container ensured inhibition uniformity in the 7-layer lettuce sample. </LI> <LI> Sensory and metabolic properties of the bulk lettuce were unaffected by DACP. </LI> </UL> </P>

In-Package Atmospheric Cold Plasma Treatment for Microbiological Safety and Preservation of Grape Tomatoes

Si Hyeon Roh,Brendan A. Niemira,Sea C. Min 한국산업식품공학회 2016 학술대회 및 심포지엄 Vol.2016 No.10

Effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inhibition of Salmonella and the storability of grape tomato were investigated. Grape tomatoes, with or without inoculation with a cocktail of three strains of Salmonella (~8 log CFU/g tomato), were packaged in a polyethylene terephthalate commercial clamshell container and cold plasma-treated at 35 kVat 1.1 kHz for 3 min using an DACP treatment system equipped with a pin-type high-voltage electrode. DACP treatment resulted in ~1 log CFU/tomato reduction of Salmonella, irrespectively of the size of container (316, 595vs. 758 cm3), the number of grape tomatoes in the container (3, 7, vs. 11), and the position of the tomato in the container(P > 0.05).Rolling integrated during treatment significantly increased the Salmonella reduction rates to 3.1±0.3 and 3.3±0.8 log CFU/tomato in the single-layer and double-layer configurations of the tomato samples in the container (992 cm3), respectively. Rolling-adopted DACP initially reduced the number of total mesophilic aerobes and yeast and molds in the double layer configuration of tomato samples by 1.3±0.3 and 1.5±0.2 log CFU/tomato, respectively, without altering the color and firmness of the tomatoes. The growth of Salmonella, total aerobes, and yeast and molds on DACP-treated grape tomatoes was effectively prevented during storage at 10 °C. DACP treatment did not influence the tomato color index (a*/b*), firmness, weight loss, pH, total soluble solid content, and lycopene concentration of grape tomatoes at 10 and 25 °C (P> 0.05). DACP treatment holds promise as a post-packaging process for improving microbial safety against Salmonella and storability of fresh grape tomatoes.

Dielectric barrier discharge atmospheric cold plasma inhibits Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus in Romaine lettuce

Min, S.C.,Roh, S.H.,Niemira, B.A.,Sites, J.E.,Boyd, G.,Lacombe, A. Elsevier Science Publishers 2016 International journal of food microbiology Vol.237 No.-

<P>The present study investigated the effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus (TV) on Romaine lettuce, assessing the influences of moisture vaporization, modified atmospheric packaging (MAP), and post-treatment storage on the inactivation of these pathogens. Romaine lettuce was inoculated with E. coli O157:H7, Salmonella, L. monocytogenes (similar to 6 log CFU/g lettuce), or TV (similar to 2 log PFU/g lettuce) and packaged in either a Petri dish (diameter: 150 mm, height: 15 mm) or a Nylon/polyethylene pouch (152 x 254 mm) with and without moisture vaporization. Additionally, a subset of pouch-packaged leaves was flushed with O-2 at 5% or 10% (balance N-2). All of the packaged lettuce samples were treated with DACP at 34.8 kV for 5 min and then analyzed either immediately or following post-treatment storage for 24 h at 4 degrees C to assess the inhibition of microorganisms. DACP treatment inhibited E. coli O157:H7, Salmonella, L. monocytogenes, and TV by 1.1 +/- 0.4, 0.4 +/- 03, 1.0 +/- 0.5 log CFU/g, and 13 +/- 0.1 log PFU/g, respectively, without environmental modifications of moisture or gas in the packages. The inhibition of the bacteria was not significantly affected by packaging type or moisture vaporization (p > 0.05) but a reduced-oxygen MAP gas composition attenuated the inhibition rates of E. coli O157:H7 and TV. L. monocytogenes continued to decline by an additional 0.6 log CFU/g in post-treatment cold storage for 24 h. Additionally, both rigid and flexible conventional plastic packages appear to be suitable for the in-package decontamination of lettuce with DACP. Published by Elsevier B.V.</P>

Inactivation of Escherichia coli O157:H7 and Aerobic Microorganisms in Romaine Lettuce Packaged in a Commercial Polyethylene Terephthalate Container Using Atmospheric Cold Plasma

MIN, SEA C.,ROH, SI HYEON,BOYD, GLENN,SITES, JOSEPH E.,UKNALIS, JOSEPH,FAN, XUETONG,NIEMIRA, BRENDAN A. ational Association for Food Protection 2017 Journal of food protection Vol.80 No.1

<B>ABSTRACT</B><P>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, CO2 generation, 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, CO2 generation, weight, and surface morphology of lettuce during storage (P &gt; 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.</P>

Survival of Salmonella Typhimurium on soybean sprouts following treatments with gaseous chlorine dioxide and biocontrol Pseudomonas bacteria

Armarynette Berrios-Rodriguez,Ocen M. Olanya,Bassam A. Annous,Jennifer M. Cassidy,Lynette Orellana,Brendan A. Niemira 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.2

Control of Salmonella Typhimurium on sprouts is crucial for food and consumer safety. In this study, natural microflora on soybean seed was assessed and effects of gaseous chlorine dioxide (ClO2) and biocontrol Pseudomonas on the survival of S. Typhimurium on soybean sprouts were evaluated. Sprouts were dip-inoculated with S. Typhimurium prior to the application of the biocontrol (P. chlororaphis and P. fluorescens). After inoculation with S. Typhimurium, the sprouts were treated with ClO2 at 0.4 mg/L for 1 h (90% R.H., 13oC). Pseudomonas strains and Salmonella were recovered on Pseudomonas Agar F (PAF) and xylose lysine tergitol-4 (XLT-4) media, respectively. Pseudomonas strains reduced Salmonella by <1 log colony forming units (CFU)/g of sprouts, whereas S. Typhimurium on soybean sprouts was reduced from 2.55 to 5.35 logs CFU/g by ClO2. Gaseous ClO2 treatment reduced S. Typhimurium by 3.90 (0 h), 4.47 (24 h), and 3.61 log CFU/g (168 h). It was concluded that ClO2 and biocontrol treatment can enhance sprout safety.