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Brendan A Niemira - One of the best experts on this subject based on the ideXlab platform.
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Gamma Irradiation Influences the Survival and Regrowth of Antibiotic-Resistant Bacteria and Antibiotic-Resistance Genes on Romaine Lettuce
Frontiers Media S.A., 2019Co-Authors: Vaishali Dharmarha, Brendan A Niemira, Giselle Guron, Renee R. Boyer, Amy Pruden, Laura K. Strawn, Monica A. PonderAbstract:Contamination of Romaine Lettuce with human pathogens, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) occurs during production. Post-harvest interventions are emplaced to mitigate pathogens, but could also mitigate ARB and ARGs on vegetables. The objective of this research was to determine changes to Lettuce phyllosphere microbiota, inoculated ARB, and the resistome (profile of ARGs) following washing with a sanitizer, gamma irradiation, and cold storage. To simulate potential sources of pre-harvest contamination, Romaine Lettuce leaves were inoculated with compost slurry containing antibiotic-resistant strains of pathogenic (Escherichia coli O157:H7) and representative of spoilage bacteria (Pseudomonas aeruginosa). Various combinations of washing with sodium hypochlorite (50 ppm free chlorine), packaging under modified atmosphere (98% nitrogen), irradiating (1.0 kGy) and storing at 4°C for 1 day versus 14 days were compared. Effects of post-harvest treatments on the resistome were profiled by shotgun metagenomic sequencing. Bacterial 16S rRNA gene amplicon sequencing was performed to determine changes to the phyllosphere microbiota. Survival and regrowth of inoculated ARB were evaluated by enumeration on selective media. Washing Lettuce in water containing sanitizer was associated with reduced abundance of ARG classes that confer resistance to glycopeptides, β-lactams, phenicols, and sulfonamides (Wilcoxon, p < 0.05). Washing followed by irradiation resulted in a different resistome chiefly due to reductions in multidrug, triclosan, polymyxin, β-lactam, and quinolone ARG classes (Wilcoxon, p < 0.05). Irradiation followed by storage at 4°C for 14 days led to distinct changes to the β-diversity of the host bacteria of ARGs compared to 1 day after treatment (ANOSIM, R = 0.331; p = 0.003). Storage of washed and irradiated Lettuce at 4°C for 14 days increased the relative abundance of Pseudomonadaceae and Carnobacteriaceae (Wilcoxon, p < 0.05), two groups whose presence correlated with detection of 10 ARG classes on the Lettuce phyllosphere (p < 0.05). Irradiation resulted in a significant reduction (∼3.5 log CFU/g) of inoculated strains of E. coli O157:H7 and P. aeruginosa (ANOVA, p < 0.05). Results indicate that washing, irradiation and storage of modified atmosphere packaged Lettuce at 4°C are effective strategies to reduce antibiotic-resistant E. coli O157:H7 and P. aeruginosa and relative abundance of various ARG classes
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in package inhibition of e coli o157 h7 on bulk Romaine Lettuce using cold plasma
Food Microbiology, 2017Co-Authors: Brendan A Niemira, Sea C Min, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Joseph Uknalis, Xuetong FanAbstract:Abstract Dielectric barrier discharge atmospheric cold plasma (DACP) treatment was evaluated for the inactivation of Escherichia coli 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 E. coli 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 (P > 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 E. coli 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.
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inactivation of escherichia coli o157 h7 and aerobic microorganisms in Romaine Lettuce packaged in a commercial polyethylene terephthalate container using atmospheric cold plasma
Journal of Food Protection, 2017Co-Authors: Xuetong Fan, Sea C Min, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Joseph Uknalis, Brendan A NiemiraAbstract: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 > 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.
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dielectric barrier discharge atmospheric cold plasma inhibits escherichia coli o157 h7 salmonella listeria monocytogenes and tulane virus in Romaine Lettuce
International Journal of Food Microbiology, 2016Co-Authors: Sea C Min, Brendan A Niemira, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Alison LacombeAbstract: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 (~6logCFU/g Lettuce), or TV (~2logPFU/g Lettuce) and packaged in either a Petri dish (diameter: 150mm, height: 15mm) or a Nylon/polyethylene pouch (152×254mm) with and without moisture vaporization. Additionally, a subset of pouch-packaged leaves was flushed with O2 at 5% or 10% (balance N2). All of the packaged Lettuce samples were treated with DACP at 34.8kV for 5min and then analyzed either immediately or following post-treatment storage for 24h at 4°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±0.3, 1.0±0.5logCFU/g, and 1.3±0.1logPFU/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 0.6logCFU/g in post-treatment cold storage for 24h. Additionally, both rigid and flexible conventional plastic packages appear to be suitable for the in-package decontamination of Lettuce with DACP.
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effects of gamma irradiation on the survival of pseudomonas fluorescens inoculated on Romaine Lettuce and baby spinach
Lwt - Food Science and Technology, 2015Co-Authors: Ocen M Olanya, Brendan A Niemira, John G PhillipsAbstract:Abstract Irradiation of fresh fruits and vegetables has been utilized as a post-harvest intervention measure to inactivate microbial pathogen on produce. The objectives of this research were to determine the survival (D 10 values) of Pseudomonas fluorescens (Pf) strains 2-79, Q8R1, Q287, surface inoculated on baby spinach and Romaine Lettuce; and Pf strains suspended in buffer peptone water (BPW). Gamma irradiation doses of 0 (control), 0.25, 0.50, 0.75 and 1.0 kGy were applied on P. fluorescens inoculated on produce and stored for 24 h at 4 °C. On spinach and Romaine Lettuce, the D 10 values of P. fluorescens ranged from 0.04 ± 0.01 to 0.05 ± 0.02 and from 0.05 ± 0.03 to 0.06 ± 0.03 kGy, respectively. Pf had high sensitivity to irradiation and its populations varied on spinach and on Romaine Lettuce. These results indicate that low irradiation values are required to inactivate Pf on produce resulting with low bacterial survival.
Edward R Atwill - One of the best experts on this subject based on the ideXlab platform.
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experimental in field transfer and survival of escherichia coli from animal feces to Romaine Lettuce in salinas valley california
Microorganisms, 2019Co-Authors: Saharuetai Jeamsripong, Jennifer A Chase, Michele T Jayrussell, Robert L Buchanan, Edward R AtwillAbstract:This randomized controlled trial characterized the transfer of E. coli from animal feces and/or furrow water onto adjacent heads of Lettuce during foliar irrigation, and the subsequent survival of bacteria on the adaxial surface of Lettuce leaves. Two experiments were conducted in Salinas Valley, California: (1) to quantify the transfer of indicator E. coli from chicken and rabbit fecal deposits placed in furrows to surrounding Lettuce heads on raised beds, and (2) to quantify the survival of inoculated E. coli on Romaine Lettuce over 10 days. E. coli was recovered from 97% (174/180) of Lettuce heads to a maximal distance of 162.56 cm (5.33 ft) from feces. Distance from sprinklers to feces, cumulative foliar irrigation, and Lettuce being located downwind of the fecal deposit were positively associated, while distance from fecal deposit to Lettuce was negatively associated with E. coli transference. E. coli exhibited decimal reduction times of 2.2 and 2.5 days when applied on the adaxial surface of leaves within a chicken or rabbit fecal slurry, respectively. Foliar irrigation can transfer E. coli from feces located in a furrow onto adjacent heads of Lettuce, likely due to the kinetic energy of irrigation droplets impacting the fecal surface and/or impacting furrow water contaminated with feces, with the magnitude of E. coli enumerated per head of Lettuce influenced by the distance between Lettuce and the fecal deposit, cumulative application of foliar irrigation, wind aspect of Lettuce relative to feces, and time since final irrigation. Extending the time period between foliar irrigation and harvest, along with a 152.4 cm (5 ft) no-harvest buffer zone when animal fecal material is present, may substantially reduce the level of bacterial contamination on harvested Lettuce.
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environmental inactivation and irrigation mediated regrowth of escherichia coli o157 h7 on Romaine Lettuce when inoculated in a fecal slurry matrix
PeerJ, 2019Co-Authors: Jennifer A Chase, Melissa L Partyka, Ronald F Bond, Edward R AtwillAbstract:Field trials were conducted in July-August and October 2012 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to Romaine Lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, California. One-half milliliter of rabbit, chicken, or pig fecal slurry, containing an average of 4.05 × 107 CFU E. coli O157:H7 (C0), was inoculated onto the upper (adaxial) surface of a lower leaf on 288 heads of Lettuce per trial immediately following a 2.5 h irrigation event. To estimate the bacterial inactivation rate as a function of time, fecal matrix, irrigation and seasonal climate effects, sets of Lettuce heads (n = 28) were sampled each day over 10 days and the concentration of E. coli O157:H7 (Ct) determined. E. coli O157:H7 was detected on 100% of heads during the 10-day duration, with concentrations ranging from ≤340 MPN/head (∼5-log reduction) to >3.45 × 1012 MPN/head (∼5-log growth). Relative to C0, on day 10 (Ct = 12) we observed an overall 2.6-log and 3.2-log mean reduction of E. coli O157:H7 in July and October, respectively. However, we observed relative maximum concentrations due to bacterial growth on day 6 (maximum Ct = 8) apparently stimulated by foliar irrigation on day 5. From this maximum there was a mean 5.3-log and 5.1-log reduction by day 10 (Ct = 12) for the July and October trials, respectively. This study provides insight into the inactivation and growth kinetics of E. coli O157:H7 on Romaine Lettuce leaves under natural field conditions. This study provides evidence that harvesting within 24 h post irrigation has the potential to increase the concentration of E. coli O157:H7 contamination, if present on heads of Romaine Lettuce; foliar irrigation can temporarily stimulate substantial regrowth of E. coli O157:H7.
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inactivation of escherichia coli o157 h7 on Romaine Lettuce when inoculated in a fecal slurry matrix
Journal of Food Protection, 2017Co-Authors: Jennifer A Chase, Edward R Atwill, Melissa L Partyka, Ronald F Bond, David OryangAbstract:ABSTRACT A field trial was conducted in July 2011 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to Romaine Lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, CA. One-half milliliter of rabbit fecal slurry, containing 6.3 × 107 CFU of E. coli O157:H7, was inoculated onto the upper (adaxial) surface of a lower leaf on 240 heads of Lettuce within 30 min after a 2.5-h irrigation event. Forty-eight Romaine Lettuce heads were collected per event at 2.5 h (day 0.1), 19.75 h (day 0.8), 43.25 h (day 1.8), 67.25 h (day 2.8), and 91.75 h (day 3.8) postinoculation and were analyzed for the concentration of E. coli O157:H7 (Ct). E. coli O157:H7 was detected on 100% of collected heads in concentrations ranging from 340 to 3.40 × 1010 most probable number (MPN) per head. Enumeration data indicate substantial growth of E. coli O157:H7 postinoculation (2.5 h), leading to elevated concentrations, 1 to 3 log above the starting inoculum co...
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transfer of escherichia coli o157 h7 from simulated wildlife scat onto Romaine Lettuce during foliar irrigation
Journal of Food Protection, 2015Co-Authors: Edward R Atwill, Michael Cahn, Jennifer A Chase, Ronald F Bond, David Oryang, S T Koike, Maren Anderson, Amirhossein Mokhtari, Sherri DennisAbstract:A field trial in Salinas Valley, California, was conducted during July 2011 to quantify the microbial load that transfers from wildlife feces onto nearby Lettuce during foliar irrigation. Romaine Lettuce was grown using standard commercial practices and irrigated using an impact sprinkler design. Five grams of rabbit feces was spiked with 1.29 × 108 CFU of Escherichia coli O157:H7 and placed −3, −2, and −1 days and immediately before a 2-h irrigation event. Immediately after irrigation, 168 heads of Lettuce ranging from ca. 23 to 69 cm (from 9 to 27 in.) from the fecal deposits were collected, and the concentration of E. coli O157:H7 was determined. Thirty-eight percent of the collected Lettuce heads had detectable E. coli O157:H7, ranging from 1 MPN to 2.30 × 105 MPN per head and a mean concentration of 7.37 × 103 MPN per head. Based on this weighted arithmetic mean concentration of 7.37 × 103 MPN of bacteria per positive head, only 0.00573% of the original 5 g of scat with its mean load of 1.29 × 108 CF...
Xuetong Fan - One of the best experts on this subject based on the ideXlab platform.
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hydrogen peroxide residue on tomato apple cantaloupe and Romaine Lettuce after treatments with cold plasma activated hydrogen peroxide aerosols
Journal of Food Protection, 2021Co-Authors: Yuanyuan Song, Xuetong FanAbstract:ABSTRACT Hydrogen peroxide (H2O2) has long been studied as an aqueous sanitizer to enhance microbial safety of fresh produce. Recently, we demonstrated that cold plasma-activated H2O2 aerosols, hereafter called ionized hydrogen peroxide (iHP), reduced populations of Salmonella, Listeria, and Escherichia coli by up to 5.5 log on surfaces of various produce items. However, the amount and fate of H2O2 residue left on fresh produce after treatments have not been evaluated. In the present study, H2O2 residue levels on apples, tomatoes, cantaloupe, and Romaine Lettuce were analyzed after treatments with 7.8% iHP at conditions that had been optimized and tailored for Salmonella reductions and each produce item. Results showed that higher residue levels were found on Lettuce than on cantaloupe, tomatoes, and apples immediately after treatments. During storage at 10 and 22°C, H2O2 levels decreased rapidly and fell below 1 mg/kg within 1 day after treatments for all fresh produce items. Furthermore, the decrease was faster at 22°C than at 10°C. Most importantly, the levels of H2O2 residue on the fresh produce items were lower than those after wash with 1% H2O2 for 1 min. Overall, our results demonstrated that levels of H2O2 residue on fresh produce surfaces decomposed rapidly after treatment with iHP and did not appear to pose a safety concern after 1 day of storage. HIGHLIGHTS
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effects of direct and in package pulsed light treatment on inactivation of e coli o157 h7 and reduction of microbial loads in Romaine Lettuce
Lwt - Food Science and Technology, 2021Co-Authors: Sudarsan Mukhopadhyay, Ocen M Olanya, Kimberly J B Sokorai, Dike O Ukuku, Tony Z Jin, Xuetong Fan, Juncai Leng, Vijay K JunejaAbstract:Abstract The microbial safety of fresh produce continues to be a real concern. Novel nonthermal technologies are required to lessen the risk of pathogen contamination. The objective of this research was to develop and evaluate the effects of direct and in-package pulsed light (PL) treatment on the survival of E. coli O157:H7 in Romaine Lettuce. Treatment influence on reduction of background microbial loads of Romaine Lettuce was also explored. A three strain-cocktail of E. coli O157:H7 was selected for inoculum preparation for their link with foodborne outbreaks. Surface inoculated Romaine Lettuce pieces (2.5 × 2.5 cm) was subjected to pulsed light treatment for a maximum of 1 min (63 J/cm2). Polyethylene (PE) films of 0.00254, 0.00508 and 0.00762 cm thickness with ample UV transmission (54–83%) ability were used for packaging. PL treatment of 10 s, equivalent to a dose of 10.5 J/cm2, was considered optimum beyond which wilting of leaves was observed. Both direct and in-package treatment provided greater than 1 log reduction of the pathogen in 1 s (1.05 J/cm2). Direct treatment resulted in 2.68 ± 0.37 log CFU/g reduction of E. coli O157:H7 at optimal dose, whereas log reductions were decreased to 2.52 ± 0.19, 2.31 ± 0.34 and 2.18 ± 0.25 log CFU/g for Romaine Lettuce in 0.00254, 0.00508 and 0.00762 cm thickness packaging enclosures respectively. The decrease in log reductions was not significantly (P > 0.05) affected by film thickness. No significant difference (P > 0.05) in E. coli O157:H7 decontamination efficacy between packaged and unpackaged Romaine Lettuce was observed due to PL treatment. The initial total aerobic bacteria and mold and yeast populations were also reduced significantly (P 1 log, due to the treatment. Overall, the results of this work demonstrate that PL treatment may be used to enhance microbial safety and reduce post processing contamination of packaged Romaine Lettuce.
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in package inhibition of e coli o157 h7 on bulk Romaine Lettuce using cold plasma
Food Microbiology, 2017Co-Authors: Brendan A Niemira, Sea C Min, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Joseph Uknalis, Xuetong FanAbstract:Abstract Dielectric barrier discharge atmospheric cold plasma (DACP) treatment was evaluated for the inactivation of Escherichia coli 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 E. coli 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 (P > 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 E. coli 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.
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inactivation of escherichia coli o157 h7 and aerobic microorganisms in Romaine Lettuce packaged in a commercial polyethylene terephthalate container using atmospheric cold plasma
Journal of Food Protection, 2017Co-Authors: Xuetong Fan, Sea C Min, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Joseph Uknalis, Brendan A NiemiraAbstract: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 > 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.
Jennifer A Chase - One of the best experts on this subject based on the ideXlab platform.
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experimental in field transfer and survival of escherichia coli from animal feces to Romaine Lettuce in salinas valley california
Microorganisms, 2019Co-Authors: Saharuetai Jeamsripong, Jennifer A Chase, Michele T Jayrussell, Robert L Buchanan, Edward R AtwillAbstract:This randomized controlled trial characterized the transfer of E. coli from animal feces and/or furrow water onto adjacent heads of Lettuce during foliar irrigation, and the subsequent survival of bacteria on the adaxial surface of Lettuce leaves. Two experiments were conducted in Salinas Valley, California: (1) to quantify the transfer of indicator E. coli from chicken and rabbit fecal deposits placed in furrows to surrounding Lettuce heads on raised beds, and (2) to quantify the survival of inoculated E. coli on Romaine Lettuce over 10 days. E. coli was recovered from 97% (174/180) of Lettuce heads to a maximal distance of 162.56 cm (5.33 ft) from feces. Distance from sprinklers to feces, cumulative foliar irrigation, and Lettuce being located downwind of the fecal deposit were positively associated, while distance from fecal deposit to Lettuce was negatively associated with E. coli transference. E. coli exhibited decimal reduction times of 2.2 and 2.5 days when applied on the adaxial surface of leaves within a chicken or rabbit fecal slurry, respectively. Foliar irrigation can transfer E. coli from feces located in a furrow onto adjacent heads of Lettuce, likely due to the kinetic energy of irrigation droplets impacting the fecal surface and/or impacting furrow water contaminated with feces, with the magnitude of E. coli enumerated per head of Lettuce influenced by the distance between Lettuce and the fecal deposit, cumulative application of foliar irrigation, wind aspect of Lettuce relative to feces, and time since final irrigation. Extending the time period between foliar irrigation and harvest, along with a 152.4 cm (5 ft) no-harvest buffer zone when animal fecal material is present, may substantially reduce the level of bacterial contamination on harvested Lettuce.
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environmental inactivation and irrigation mediated regrowth of escherichia coli o157 h7 on Romaine Lettuce when inoculated in a fecal slurry matrix
PeerJ, 2019Co-Authors: Jennifer A Chase, Melissa L Partyka, Ronald F Bond, Edward R AtwillAbstract:Field trials were conducted in July-August and October 2012 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to Romaine Lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, California. One-half milliliter of rabbit, chicken, or pig fecal slurry, containing an average of 4.05 × 107 CFU E. coli O157:H7 (C0), was inoculated onto the upper (adaxial) surface of a lower leaf on 288 heads of Lettuce per trial immediately following a 2.5 h irrigation event. To estimate the bacterial inactivation rate as a function of time, fecal matrix, irrigation and seasonal climate effects, sets of Lettuce heads (n = 28) were sampled each day over 10 days and the concentration of E. coli O157:H7 (Ct) determined. E. coli O157:H7 was detected on 100% of heads during the 10-day duration, with concentrations ranging from ≤340 MPN/head (∼5-log reduction) to >3.45 × 1012 MPN/head (∼5-log growth). Relative to C0, on day 10 (Ct = 12) we observed an overall 2.6-log and 3.2-log mean reduction of E. coli O157:H7 in July and October, respectively. However, we observed relative maximum concentrations due to bacterial growth on day 6 (maximum Ct = 8) apparently stimulated by foliar irrigation on day 5. From this maximum there was a mean 5.3-log and 5.1-log reduction by day 10 (Ct = 12) for the July and October trials, respectively. This study provides insight into the inactivation and growth kinetics of E. coli O157:H7 on Romaine Lettuce leaves under natural field conditions. This study provides evidence that harvesting within 24 h post irrigation has the potential to increase the concentration of E. coli O157:H7 contamination, if present on heads of Romaine Lettuce; foliar irrigation can temporarily stimulate substantial regrowth of E. coli O157:H7.
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inactivation of escherichia coli o157 h7 on Romaine Lettuce when inoculated in a fecal slurry matrix
Journal of Food Protection, 2017Co-Authors: Jennifer A Chase, Edward R Atwill, Melissa L Partyka, Ronald F Bond, David OryangAbstract:ABSTRACT A field trial was conducted in July 2011 to quantify the inactivation rate of Escherichia coli O157:H7 when mixed with fecal slurry and applied to Romaine Lettuce leaves. Lettuce was grown under commercial conditions in Salinas Valley, CA. One-half milliliter of rabbit fecal slurry, containing 6.3 × 107 CFU of E. coli O157:H7, was inoculated onto the upper (adaxial) surface of a lower leaf on 240 heads of Lettuce within 30 min after a 2.5-h irrigation event. Forty-eight Romaine Lettuce heads were collected per event at 2.5 h (day 0.1), 19.75 h (day 0.8), 43.25 h (day 1.8), 67.25 h (day 2.8), and 91.75 h (day 3.8) postinoculation and were analyzed for the concentration of E. coli O157:H7 (Ct). E. coli O157:H7 was detected on 100% of collected heads in concentrations ranging from 340 to 3.40 × 1010 most probable number (MPN) per head. Enumeration data indicate substantial growth of E. coli O157:H7 postinoculation (2.5 h), leading to elevated concentrations, 1 to 3 log above the starting inoculum co...
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transfer of escherichia coli o157 h7 from simulated wildlife scat onto Romaine Lettuce during foliar irrigation
Journal of Food Protection, 2015Co-Authors: Edward R Atwill, Michael Cahn, Jennifer A Chase, Ronald F Bond, David Oryang, S T Koike, Maren Anderson, Amirhossein Mokhtari, Sherri DennisAbstract:A field trial in Salinas Valley, California, was conducted during July 2011 to quantify the microbial load that transfers from wildlife feces onto nearby Lettuce during foliar irrigation. Romaine Lettuce was grown using standard commercial practices and irrigated using an impact sprinkler design. Five grams of rabbit feces was spiked with 1.29 × 108 CFU of Escherichia coli O157:H7 and placed −3, −2, and −1 days and immediately before a 2-h irrigation event. Immediately after irrigation, 168 heads of Lettuce ranging from ca. 23 to 69 cm (from 9 to 27 in.) from the fecal deposits were collected, and the concentration of E. coli O157:H7 was determined. Thirty-eight percent of the collected Lettuce heads had detectable E. coli O157:H7, ranging from 1 MPN to 2.30 × 105 MPN per head and a mean concentration of 7.37 × 103 MPN per head. Based on this weighted arithmetic mean concentration of 7.37 × 103 MPN of bacteria per positive head, only 0.00573% of the original 5 g of scat with its mean load of 1.29 × 108 CF...
Sea C Min - One of the best experts on this subject based on the ideXlab platform.
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in package inhibition of e coli o157 h7 on bulk Romaine Lettuce using cold plasma
Food Microbiology, 2017Co-Authors: Brendan A Niemira, Sea C Min, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Joseph Uknalis, Xuetong FanAbstract:Abstract Dielectric barrier discharge atmospheric cold plasma (DACP) treatment was evaluated for the inactivation of Escherichia coli 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 E. coli 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 (P > 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 E. coli 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.
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inactivation of escherichia coli o157 h7 and aerobic microorganisms in Romaine Lettuce packaged in a commercial polyethylene terephthalate container using atmospheric cold plasma
Journal of Food Protection, 2017Co-Authors: Xuetong Fan, Sea C Min, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Joseph Uknalis, Brendan A NiemiraAbstract: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 > 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.
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dielectric barrier discharge atmospheric cold plasma inhibits escherichia coli o157 h7 salmonella listeria monocytogenes and tulane virus in Romaine Lettuce
International Journal of Food Microbiology, 2016Co-Authors: Sea C Min, Brendan A Niemira, Si Hyeon Roh, Glenn Boyd, Joseph Sites, Alison LacombeAbstract: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 (~6logCFU/g Lettuce), or TV (~2logPFU/g Lettuce) and packaged in either a Petri dish (diameter: 150mm, height: 15mm) or a Nylon/polyethylene pouch (152×254mm) with and without moisture vaporization. Additionally, a subset of pouch-packaged leaves was flushed with O2 at 5% or 10% (balance N2). All of the packaged Lettuce samples were treated with DACP at 34.8kV for 5min and then analyzed either immediately or following post-treatment storage for 24h at 4°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±0.3, 1.0±0.5logCFU/g, and 1.3±0.1logPFU/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 0.6logCFU/g in post-treatment cold storage for 24h. Additionally, both rigid and flexible conventional plastic packages appear to be suitable for the in-package decontamination of Lettuce with DACP.
