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Ding Q, Gu G, Nou X, Micallef SA. Cultivar was more influential than bacterial strain and other experimental factors in recovery of Escherichia coli O157:H7 populations from inoculated live Romaine lettuce plants. Microbiol Spectr 2024; 12:e0376723. [PMID: 38363139 PMCID: PMC10986467 DOI: 10.1128/spectrum.03767-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 01/22/2024] [Indexed: 02/17/2024] Open
Abstract
The varied choice of bacterial strain, plant cultivar, and method used to inoculate, retrieve, and enumerate Escherichia coli O157:H7 from live plants could affect comparability among studies evaluating lettuce-enterobacterial interactions. Cultivar, bacterial strain, incubation time, leaf side inoculated, and sample processing method were assessed for their influence in recovering and quantifying E. coli O157:H7 from live Romaine lettuce. Cultivar exerted the strongest effect on E. coli O157:H7 counts, which held up even when cultivar was considered in interactions with other factors. Recovery from the popularly grown green Romaine "Rio Bravo" was higher than from the red variety "Outredgeous." Other modulating variables were incubation time, strain, and leaf side inoculated. Sample processing method was not significant. Incubation for 24 hours post-lettuce inoculation yielded greater counts than 48 hours, but was affected by lettuce cultivar, bacterial strain, and leaf side inoculated. Higher counts obtained for strain EDL933 compared to a lettuce outbreak strain 2705C emphasized the importance of selecting relevant strains for the system being studied. Inoculating the abaxial side of leaves gave higher counts than adaxial surface inoculation, although this factor interacted with strain and incubation period. Our findings highlight the importance of studying interactions between appropriate bacterial strains and plant cultivars for more relevant research results, and of standardizing inoculation and incubation procedures. The strong effect of cultivar exerted on the E. coli O157:H7-lettuce association supports the need to start reporting cultivar information for illness outbreaks to facilitate the identification and study of plant traits that impact food safety risk.IMPORTANCEThe contamination of Romaine lettuce with Escherichia coli O157:H7 has been linked to multiple foodborne disease outbreaks, but variability in the methods used to evaluate E. coli O157:H7 association with live lettuce plants complicates the comparability of different studies. In this study, various experimental variables and sample processing methods for recovering and quantifying E. coli O157:H7 from live Romaine lettuce were assessed. Cultivar was found to exert the strongest influence on E. coli O157:H7 retrieval from lettuce. Other modulating factors were bacterial incubation time on plants, strain, and leaf side inoculated, while sample processing method had no impact. Our findings highlight the importance of selecting relevant cultivars and strains, and of standardizing inoculation and incubation procedures, in these types of assessments. Moreover, results support the need to start reporting cultivars implicated in foodborne illness outbreaks to facilitate the identification and study of plant traits that impact food safety risk.
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Affiliation(s)
- Qiao Ding
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland, USA
| | - Ganyu Gu
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, Maryland, USA
| | - Xiangwu Nou
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, Maryland, USA
| | - Shirley A. Micallef
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, Maryland, USA
- Center for Food Safety and Security Systems, University of Maryland, College Park, Maryland, USA
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Celiz MD, Morehouse KM, Ridge CD, Chen F, deJager LS, Begley TH. Extraction and analysis of an organophosphate salt nucleating agent from irradiated polypropylene resin. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2022; 39:1009-1020. [PMID: 35302911 DOI: 10.1080/19440049.2022.2037727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Although it is well-established that irradiation of produce can reduce food-borne pathogens and spoilage organisms, data on the effect of irradiation on polymer additives in food packaging materials are limited, particularly for those additives used in packaging leafy greens or in current food packaging materials. We investigated the effects of irradiating a nucleating agent, aluminium, hydroxybis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo [d,g][1,3,2]dioxaphosphocin 6-oxidato]- (CAS Reg. No. 151841-65-5), at doses of 1-20 kGy in polypropylene. That nucleating agent was then extracted using accelerated solvent extraction and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), liquid chromatography-photodiode array detection (LC-PDA), and solid-state nuclear magnetic resonance (SSNMR) spectroscopy. We found this nucleating agent was not significantly affected by radiation treatment up to 20 kGy. Therefore, this nucleating agent could potentially be useful in food packaging materials that will be irradiated at doses of 20 kGy or less. Establishing which additives are stable under anticipated irradiation doses will help support safety evaluation of food packaging materials.
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Affiliation(s)
- Mary Dawn Celiz
- Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD, USA
| | - Kim M Morehouse
- Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD, USA
| | - Clark D Ridge
- Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD, USA
| | - Fu Chen
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD, USA
| | - Lowri S deJager
- Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD, USA
| | - Timothy H Begley
- Center for Food Safety and Applied Nutrition, US Food and Drug Administration, College Park, MD, USA
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3
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Tan J, Karwe MV. Inactivation of Enterobacter aerogenes on the surfaces of fresh-cut purple lettuce, kale, and baby spinach leaves using plasma activated mist (PAM). INNOV FOOD SCI EMERG 2021. [DOI: 10.1016/j.ifset.2021.102868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Lee S, Mok C, Lee J. Photocatalytically Enhanced Inactivation of Internalized Pathogenic Bacteria in Fresh Produce Using UV Irradiation with Nano-Titanium Dioxide. J Food Prot 2021; 84:820-826. [PMID: 33302297 DOI: 10.4315/jfp-20-348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 12/10/2020] [Indexed: 11/11/2022]
Abstract
ABSTRACT Once pathogens are internalized in fresh produce, they pose a challenging food safety issue because they are not effectively inactivated by conventional rinsing or sanitization. To protect food safety and public health, the objectives of this study were to examine internalized levels of foodborne pathogens in different types of fresh produce and to investigate the effectiveness of photocatalytically enhanced inactivation of internalized pathogens in fresh produce using UV irradiation with titanium dioxide (TiO2). For this, green fluorescent protein-labeled Salmonella Typhimurium and Escherichia coli O157:H7 were inoculated on the leaf surface of four types of fresh produce (∼108 CFU per leaf), and varying concentrations of TiO2 suspension (0.50, 0.75, 1.00, 1.25, and 1.50 μg/mL) were applied to the surface of contaminated leaves. Depending on the nature of each vegetable, the internalized bacterial level differed (2 to 5 log CFU/g of leaf). When UV irradiation (6,000 J/m2) was applied, the internalized Salmonella Typhimurium and E. coli levels were reduced by 0.8 to 2.4 log CFU per leaf; with TiO2, the reduction was 1.1 to 3.7 log CFU per leaf. The inactivation efficiency increased as the TiO2 concentration increased (up to 1.50 μg per leaf). These results indicate that TiO2 application enhanced the photocatalytic inactivation of internalized foodborne pathogens. The application of TiO2 would be most practical before UV irradiation and before distributing the produce. This study established a platform for future research on the inactivation of various internalized pathogens for protecting public health and scaling up fresh produce treatments by the food industry. HIGHLIGHTS
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Affiliation(s)
- Seungjun Lee
- College of Public Health, Division of Environmental Health Sciences, Gachon University, Seongnam 13120, South Korea.,(ORCID: https://orcid.org/0000-0002-2848-3521 [S.L.])
| | - Chulkyoon Mok
- Department of Food Science and Biotechnology, Gachon University, Seongnam 13120, South Korea
| | - Jiyoung Lee
- College of Public Health, Division of Environmental Health Sciences, Gachon University, Seongnam 13120, South Korea.,Department of Food Science and Technology, The Ohio State University, Columbus, Ohio 43210, USA
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5
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Mulaosmanovic E, Windstam ST, Vågsholm I, Alsanius BW. Size Matters: Biological and Food Safety Relevance of Leaf Damage for Colonization of Escherichia coli O157:H7 gfp. Front Microbiol 2021; 11:608086. [PMID: 33584570 PMCID: PMC7873480 DOI: 10.3389/fmicb.2020.608086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/14/2020] [Indexed: 11/13/2022] Open
Abstract
This study examined the biological and food safety relevance of leaf lesions for potential invasion of food pathogens into the plant tissue (internalization). This was done by determining the role of artificial leaf damage in terms of damaged leaf area on proliferation of E. coli O157:H7 gfp+. In a two-factorial experiment, unwashed fresh baby leaf spinach (Spinacia oleracea L.) was subjected to four damage levels (undamaged, low, moderate, high damage; factor 1) and three incubation intervals (0, 1, 2 days post-inoculation; factor 2). Individual leaves were immersed for 15 s in a suspension loaded with E. coli O157:H7 gfp+ (106 CFU × mL–1). The leaves were analyzed individually using image analysis tools to quantify leaf area and number and size of lesions, and using confocal laser scanning and scanning electron microscopy to visualize leaf lesions and presence of the introduced E. coli strain on and within the leaf tissue. Prevalence of E. coli O157:H7 gfp+ was assessed using a culture-dependent technique. The results showed that size of individual lesions and damaged leaf area affected depth of invasion into plant tissue, dispersal to adjacent areas, and number of culturable E. coli O157:H7 gfp+ directly after inoculation. Differences in numbers of the inoculant retrieved from leaf macerate evened out from 2 days post-inoculation, indicating rapid proliferation during the first day post-inoculation. Leaf weight was a crucial factor, as lighter spinach leaves (most likely younger leaves) were more prone to harbor E. coli O157:H7 gfp+, irrespective of damage level. At the high inoculum density used, the risk of consumers’ infection was almost 100%, irrespective of incubation duration or damage level. Even macroscopically intact leaves showed a high risk for infection. These results suggest that the risk to consumers is correlated with how early in the food chain the leaves are contaminated, and the degree of leaf damage. These findings should be taken into account in different steps of leafy green processing. Further attention should be paid to the fate of viable, but non-culturable, shiga-toxigenic E. coli on and in ready-to-eat leafy vegetables.
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Affiliation(s)
- Emina Mulaosmanovic
- Microbial Horticulture Unit, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Sofia T Windstam
- Microbial Horticulture Unit, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
| | - Ivar Vågsholm
- Bacteriology and Food Safety Unit, Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Beatrix W Alsanius
- Microbial Horticulture Unit, Department of Biosystems and Technology, Swedish University of Agricultural Sciences, Alnarp, Sweden
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Gao J, Jang H, Huang L, Matthews KR. Influence of product volume on water antimicrobial efficacy and cross-contamination during retail batch washing of lettuce. Int J Food Microbiol 2020; 323:108593. [PMID: 32224348 DOI: 10.1016/j.ijfoodmicro.2020.108593] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 03/11/2020] [Accepted: 03/18/2020] [Indexed: 11/15/2022]
Abstract
Fresh produce shall be thoroughly washed at the retail level prior to serving to the consumer with potable water. Foodborne pathogens if present on a product may transfer to the wash water and cross-contaminate other products immersed in the water. Typically, an entire carton of lettuce (24 heads) is washed together increasing the likelihood of cross-contamination due to the close contact between each head. This study aimed to compare the effects of two wash batch volumes - "low" (8 heads) and "high" (24 heads) on the efficacy of two commercial water antimicrobials and cross-contamination. Red leaf lettuce was spot-inoculated (~5.0 log CFU/g) with Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes. In the first batch of washing, inoculated lettuce was washed with non-inoculated lettuce, followed by reuse of the water/antimicrobials twice washing only non-inoculated lettuce. Samples of inoculated and non-inoculated lettuce were collected to determine aerobic plate count (APC) as well as the populations of STEC and L. monocytogenes. Microbiological analysis of the wash water was also conducted. Wash volume (8 versus 24 lettuce heads) had limited effects on the antimicrobial activities of the interventions evaluated. Instead, high-volume wash increased the rate of cross-contamination between non-inoculated and inoculated lettuce, and cross-contamination of non-inoculated lettuce through wash water reuse. Retailers should consider volume of product processed per batch, reuse of wash water, and use of an appropriate water antimicrobial in consideration of mitigating potential product cross-contamination.
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Affiliation(s)
- Jingwen Gao
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, United States
| | - Hyein Jang
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, United States
| | - Licheng Huang
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, United States
| | - Karl R Matthews
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, United States.
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Gurtler JB. Two Generally Recognized as Safe Surfactants plus Acidulants Inactivate Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in Suspension or on Dip-Inoculated Grape Tomatoes. J Food Prot 2020; 83:637-643. [PMID: 32221569 DOI: 10.4315/0362-028x.jfp-19-286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 11/04/2019] [Indexed: 11/11/2022]
Abstract
ABSTRACT Contamination of fresh produce with the foodborne pathogens Salmonella enterica, Listeria monocytogenes, and Escherichia coli O157:H7 continues to be problematic, resulting in outbreaks of foodborne illness and costly corporate recalls. Various individual concentrations of citric or lactic acids (0.35 to 0.61%) or isopropyl citrate (0.16 to 0.54%) combined with two generally recognized as safe surfactants, 0.025% sodium-2-ethyl-hexyl sulfate and 0.025% sodium dodecylbenzene-sulfonate, were tested against these three pathogens in suspension and when inoculated and dried on the surface of grape tomatoes. The efficacy of sodium hypochlorite (NaClO; at 46 ppm) was also evaluated under dirty and clean conditions in suspension after addition of 0.3 or 0.03% bovine serum albumin, respectively, as an organic load. NaClO (46 ppm) inactivated the three pathogens in suspension by <0.76 log CFU/mL after 5 min in the presence of 0.3% bovine serum albumin, whereas 9 and 15 ppm of free chlorine inactivated the pathogens by 0.64 and 2.77 log CFU/mL, respectively, after 5 min under clean conditions. Isopropyl citrate (0.16% acidulant) plus 0.05% total concentration of the two surfactants inactivated the pathogens in suspension by up to 7.0 log CFU/mL within 2 min. When applied to grape tomatoes for 2 min, 0.54% isopropyl citrate plus 0.025% concentrations of each of the two surfactants reduced Salmonella, E. coli O157:H7, and L. monocytogenes by as much as ca. 5.47, 4.89, and 4.19 log CFU/g, respectively. These reductions were significantly greater than those achieved with 49 ppm of free chlorine. Citric acid and lactic acid plus surfactant washes achieved greater inactivation than water-only washes, reducing Salmonella, E. coli O157:H7, and L. monocytogenes on tomatoes by up to 4.90, 4.37, and 3.98 log CFU/g, respectively. These results suggest that these combinations of acidulants and surfactants may be an effective tool for preventing cross-contamination during the washing of grape tomatoes, for reducing pathogens on the fruit itself, and as an alternative to chlorine for washing fresh produce. HIGHLIGHTS
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Affiliation(s)
- Joshua B Gurtler
- U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Food Safety and Intervention Technologies Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551, USA (ORCID: https://orcid.org/0000-0001-5844-7794)
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8
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Dharmarha V, Guron G, Boyer RR, Niemira BA, Pruden A, Strawn LK, Ponder MA. Gamma Irradiation Influences the Survival and Regrowth of Antibiotic-Resistant Bacteria and Antibiotic-Resistance Genes on Romaine Lettuce. Front Microbiol 2019; 10:710. [PMID: 31024491 PMCID: PMC6465624 DOI: 10.3389/fmicb.2019.00710] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/21/2019] [Indexed: 02/01/2023] Open
Abstract
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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Affiliation(s)
- Vaishali Dharmarha
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, United States
| | - Giselle Guron
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, United States
| | - Renee R. Boyer
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, United States
| | - Brendan A. Niemira
- Food Safety and Intervention Technologies Research Unit, USDA-ARS Eastern Regional Research Center, Wyndmoor, PA, United States
| | - Amy Pruden
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, United States
| | - Laura K. Strawn
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, United States
| | - Monica A. Ponder
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, United States
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Zhang Z, Guo H, Ma C, Xia M, White JC, Xing B, He L. Rapid and efficient removal of silver nanoparticles from plant surfaces using sodium hypochlorite and ammonium hydroxide solution. Food Control 2019. [DOI: 10.1016/j.foodcont.2018.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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10
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Huang R, Chen H. Evaluation of inactivating Salmonella on iceberg lettuce shreds with washing process in combination with pulsed light, ultrasound and chlorine. Int J Food Microbiol 2018; 285:144-151. [PMID: 30153526 DOI: 10.1016/j.ijfoodmicro.2018.08.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 08/20/2018] [Accepted: 08/21/2018] [Indexed: 10/28/2022]
Abstract
This study was conducted to investigate the Salmonella inactivation effects of washing in combination with pulsed light (PL), ultrasound, and chlorine on lettuce shreds. First, the effect of washing combined with PL and chlorine on the inactivation of Salmonella on lettuce and in wash water was evaluated in a small-scale study with clear tap water and turbid tap water containing lettuce extract and silicon dioxide. In general, water wash combined with PL (PL wash) and chlorine wash combined with PL (PL-Cl) were significantly more effective on killing Salmonella on lettuce than the chlorine wash and water wash regardless the wash water quality and inoculation method. We then tested washing combined with PL, ultrasound and chlorine using a large-scale UV setup with turbid wash water. Increasing the sample size decreased the decontamination efficacy of all the treatments. All the treatments resulted in <2 log reductions of Salmonella on lettuce shreds. For both small- and large-scale studies, treatments involving chlorine could keep the Salmonella population in wash water under the detection limit of 2 CFU/mL for almost all the replicates. Taking everything into consideration, we concluded that the combined PL-Cl treatment could be a better alternative to the chlorine wash for lettuce decontamination since it was in general more effective on inactivating Salmonella on lettuce than chlorine wash and could maintain the Salmonella level in wash water under the detection limit of 2 CFU/mL regardless the inoculation method, water quality and sample size, preventing the potential cross contamination through wash water.
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Affiliation(s)
- Runze Huang
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716-2150, USA
| | - Haiqiang Chen
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716-2150, USA.
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11
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Dharmarha V, Pulido N, Boyer RR, Pruden A, Strawn LK, Ponder MA. Effect of post-harvest interventions on surficial carrot bacterial community dynamics, pathogen survival, and antibiotic resistance. Int J Food Microbiol 2018; 291:25-34. [PMID: 30445282 DOI: 10.1016/j.ijfoodmicro.2018.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/30/2018] [Accepted: 11/07/2018] [Indexed: 12/12/2022]
Abstract
Strategies to mitigate antibiotic-resistant bacteria (ARB), including human pathogens, on raw vegetables are needed to reduce incidence of resistant infections. The objective of this research was to determine the effectiveness of standard post-harvest interventions, sanitizer washing and cold storage, to reduce ARB, including antibiotic resistant strains of the human pathogen E. coli O15:H7 and a common spoilage bacterium Pseudomonas, on raw carrots. To provide a background inoculum representing potential pre-harvest carryover of ARB, carrots were dip-inoculated in dairy cow manure compost slurry and further inoculated with known ARB. Inoculated carrots were washed with one of three treatments: sodium hypochlorite (50 ppm free chlorine), peroxyacetic acid (40 ppm peroxyacetic acid; 11.2% hydrogen peroxide), tap water (no sanitizer), or no washing (control). Washed carrots were air dried, packaged and stored at 10 °C for 7d or 2 °C for up to 60 d. Enumeration was performed using total heterotrophic plate counts (HPC), HPCs on antibiotic-containing media ("ARBs"), E. coli O157:H7, and Pseudomonas sp. immediately after washing (0 d) and after 7 d of storage. In addition to the cultured bacteria, changes to the surficial carrot microbiota were profiled by sequencing bacterial 16S rRNA gene amplicons to determine the effect of sanitizer wash, storage temperature, and time of storage (0, 1, 7, 14 and 60 d). Storage temperature, addition of a sanitizer during wash, and duration of storage significantly affected the bacterial microbiota (Wilcoxon, p < 0.05). Inclusion of either sanitizer in the wash water significantly reduced the log CFU/g of E. coli O157:H7 and Pseudomonas sp., as well as HPCs enumerated on cefotaxime- (10 μg/ml), sulfamethoxazole- (100 μg/ml), or tetracycline (3 μg/ml) supplemented media compared to the unwashed control (ANOVA, p < 0.05). However, no significant reductions to bacteria resistant to vancomycin or clindamycin occurred after washing and storage. Members of the Proteobactetria, Firmicutes, Actinobacteria, Planctomycetes, and Acidobacteria comprised the bacterial carrot microbiota. The diversity of the carrot microbiota was significantly affected by the temperature of storage and by extended storage (60 d), when spoilage began to occur. There were no significant differences to the relative abundance of bacterial groups associated with the type of sanitizer used for washing. Results of this study indicate that inclusion of a sanitizer in wash water, followed by storage at 2 °C, might be an effective strategy to prevent re-growth of pathogenic E. coli O157:H7 and reduce levels of bacteria resistant to certain antibiotics on carrots.
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Affiliation(s)
- Vaishali Dharmarha
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, USA
| | - Natalie Pulido
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, USA
| | - Renee R Boyer
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, USA
| | - Amy Pruden
- Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, USA
| | - Laura K Strawn
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, USA
| | - Monica A Ponder
- Department of Food Science and Technology, Virginia Tech, Blacksburg, VA, USA.
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12
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Nahar S, Mizan MFR, Ha AJW, Ha SD. Advances and Future Prospects of Enzyme-Based Biofilm Prevention Approaches in the Food Industry. Compr Rev Food Sci Food Saf 2018; 17:1484-1502. [DOI: 10.1111/1541-4337.12382] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/22/2018] [Accepted: 06/27/2018] [Indexed: 12/21/2022]
Affiliation(s)
- Shamsun Nahar
- Dept. of Food Science and Technology; Chung-Ang Univ.; Anseong Gyeonggi-Do 456-756 Republic of Korea
| | | | - Angela Jie-won Ha
- Dept. of Food Science and Technology; Chung-Ang Univ.; Anseong Gyeonggi-Do 456-756 Republic of Korea
| | - Sang-Do Ha
- Dept. of Food Science and Technology; Chung-Ang Univ.; Anseong Gyeonggi-Do 456-756 Republic of Korea
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13
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Osaili TM, Alaboudi AR, Al-Quran HN, Al-Nabulsi AA. Decontamination and survival of Enterobacteriaceae on shredded iceberg lettuce during storage. Food Microbiol 2018; 73:129-136. [PMID: 29526198 DOI: 10.1016/j.fm.2018.01.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 01/20/2018] [Accepted: 01/23/2018] [Indexed: 01/04/2023]
Abstract
Enterobacteriaceae family can contaminate fresh produce at any stage of production either at pre-harvest or post-harvest stages. The objectives of the current study were to i) identify Enterobacteriaceae species on iceberg lettuce, ii) compare the decontamination efficiency of water, sodium hypochlorite (free chlorine 200 ppm), peroxyacetic acid (PA 80 ppm; Kenocid 2100®) or their combinations and ionizing radiation against Enterobacteriaceae on shredded iceberg lettuce and iii) determine the survival of Enterobacteriaceae post-treatment storage of shredded iceberg lettuce at 4, 10 and 25 °C, for up to 7 days. Klebsiella pneumonia spp. pneumonia, Enterobacter cloacae, Klebsiella oxytoca, Pantoea spp., Leclercia adecarboxylata and Kluyvera ascorbate were identified on iceberg lettuce. No significant difference (P≥ 0.05) among Enterobacteriaceae survival after washing with water or sanitizing with sodium hypochlorite or Kenocid 2100® (reduction ≤ 0.6 log CFU/g) were found. Combined sanitizer treatments were more effective against Enterobacteriaceae than single washing/sanitizing treatments. Sanitization of iceberg lettuce with combined washing/sanitizing treatments reduced Enterobacteriaceae by 0.85-2.24 CFU/g. Post-treatment growth of Enterobacteriaceae during storage on samples sanitized with sodium hypochlorite and Kenocid 2100® was more than on samples washed with water. The D10-value of Enterobacteriaceae on shredded iceberg lettuce was 0.21 KGy. The reduction of Enterobacteriaceae populations on iceberg after gamma radiation (0.6 KGy) was 3 log CFU/g, however, Enterobacteriaceae counts increased post-irradiation storage by 4-5 log CFU/g. Therefore, washing shredded iceberg lettuce with combined sanitizing treatment (sodium hypochlorite/sodium hypochlorite, sodium hypochlorite/Kenocid 2100®, or Kenocid 2100®/Kenocid 2100®) for total time of 6 min or exposing it to gamma irradiation (0.6 KGy) can decrease the risk of Enterobacteriaceae (reduction ≥ 2 log). Post-washing storage of sliced iceberg lettuce (4, 10, 25 °C) could increase the risk of Enterobacteriaceae as their counts increased during storage even at low temperatures.
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Affiliation(s)
- Tareq M Osaili
- Department of Nutrition and Food Technology, Faculty of Agriculture, Jordan University of Science and Technology, Irbid, 22110, Jordan.
| | - Akram R Alaboudi
- Department of Veterinary Pathology and Public Health, Faculty of Veterinary Medicine, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Heba N Al-Quran
- Department of Nutrition and Food Technology, Faculty of Agriculture, Jordan University of Science and Technology, Irbid, 22110, Jordan
| | - Anas A Al-Nabulsi
- Department of Nutrition and Food Technology, Faculty of Agriculture, Jordan University of Science and Technology, Irbid, 22110, Jordan
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14
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Zhou B, Luo Y, Bauchan GR, Feng H, Stommel JR. Visualizing pathogen internalization pathways in fresh tomatoes using MicroCT and confocal laser scanning microscopy. Food Control 2018. [DOI: 10.1016/j.foodcont.2017.09.027] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Finten G, Garrido JI, Cova MC, Narvaiz P, Jagus RJ, Agüero MV. Safety improvement and quality retention of gamma irradiated spinach leaves. J Food Saf 2017. [DOI: 10.1111/jfs.12340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gabriel Finten
- Universidad de Buenos Aires (UBA). Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET). Instituto de Tecnologías y Ciencias de la Ingeniería (INTECIN), Laboratorio de Microbiología Industrial: Tecnología de alimentos; Av. Int. Guiraldes 2620, Ciudad Autónoma de Buenos Aires, (C1428EGA) Argentina
| | - Juan I. Garrido
- Comisión Nacional de Energía Atómica-Sección Irradiación de Alimentos-Gerencia de Aplicaciones y Tecnología de Radiaciones-Gerencia de Área Aplicaciones de la Tecnología Nuclear-(B1802AYA), Centro Atómico Ezeiza; Provincia de Buenos Aires Argentina
| | - María C. Cova
- Comisión Nacional de Energía Atómica-Sección Irradiación de Alimentos-Gerencia de Aplicaciones y Tecnología de Radiaciones-Gerencia de Área Aplicaciones de la Tecnología Nuclear-(B1802AYA), Centro Atómico Ezeiza; Provincia de Buenos Aires Argentina
| | - Patricia Narvaiz
- Comisión Nacional de Energía Atómica-Sección Irradiación de Alimentos-Gerencia de Aplicaciones y Tecnología de Radiaciones-Gerencia de Área Aplicaciones de la Tecnología Nuclear-(B1802AYA), Centro Atómico Ezeiza; Provincia de Buenos Aires Argentina
| | - Rosa J. Jagus
- Universidad de Buenos Aires (UBA). Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET). Instituto de Tecnologías y Ciencias de la Ingeniería (INTECIN), Laboratorio de Microbiología Industrial: Tecnología de alimentos; Av. Int. Guiraldes 2620, Ciudad Autónoma de Buenos Aires, (C1428EGA) Argentina
| | - María V. Agüero
- Universidad de Buenos Aires (UBA). Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET). Instituto de Tecnologías y Ciencias de la Ingeniería (INTECIN), Laboratorio de Microbiología Industrial: Tecnología de alimentos; Av. Int. Guiraldes 2620, Ciudad Autónoma de Buenos Aires, (C1428EGA) Argentina
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16
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Yoon JH, Lee SY. Review: Comparison of the effectiveness of decontaminating strategies for fresh fruits and vegetables and related limitations. Crit Rev Food Sci Nutr 2017; 58:3189-3208. [DOI: 10.1080/10408398.2017.1354813] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Jae-Hyun Yoon
- Department of Food and Nutrition, Chung-Ang University, 4726, Seodong-daero, Anseong-si, Gyeonggi-do, South Korea
| | - Sun-Young Lee
- Department of Food and Nutrition, Chung-Ang University, 4726, Seodong-daero, Anseong-si, Gyeonggi-do, South Korea
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17
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Evaluation of radio-frequency heating in controlling Salmonella enterica in raw shelled almonds. Int J Food Microbiol 2017; 254:54-61. [DOI: 10.1016/j.ijfoodmicro.2017.04.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 04/08/2017] [Accepted: 04/18/2017] [Indexed: 11/23/2022]
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18
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Ushida A, Koyama T, Nakamoto Y, Narumi T, Sato T, Hasegawa T. Antimicrobial effectiveness of ultra-fine ozone-rich bubble mixtures for fresh vegetables using an alternating flow. J FOOD ENG 2017. [DOI: 10.1016/j.jfoodeng.2017.03.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Irradiated ready-to-eat spinach leaves: How information influences awareness towards irradiation treatment and consumer's purchase intention. Radiat Phys Chem Oxf Engl 1993 2017. [DOI: 10.1016/j.radphyschem.2016.09.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Olanya OM, Niemira BA, Phillips JG. Effects of gamma irradiation on the survival of Pseudomonas fluorescens inoculated on romaine lettuce and baby spinach. Lebensm Wiss Technol 2015. [DOI: 10.1016/j.lwt.2014.12.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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21
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Rezende ACB, Igarashi MC, Destro MT, Franco BDGM, Landgraf M. Effect of gamma radiation on the reduction of Salmonella strains, Listeria monocytogenes, and Shiga toxin-producing Escherichia coli and sensory evaluation of minimally processed spinach (Tetragonia expansa). J Food Prot 2014; 77:1768-72. [PMID: 25285495 DOI: 10.4315/0362-028x.jfp-14-108] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This study evaluated the effects of irradiation on the reduction of Shiga toxin-producing Escherichia coli (STEC), Salmonella strains, and Listeria monocytogenes, as well as on the sensory characteristics of minimally processed spinach. Spinach samples were inoculated with a cocktail of three strains each of STEC, Salmonella strains, and L. monocytogenes, separately, and were exposed to gamma radiation doses of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 kGy. Samples that were exposed to 0.0, 1.0, and 1.5 kGy and kept under refrigeration (4°C) for 12 days were submitted to sensory analysis. D10 -values ranged from 0.19 to 0.20 kGy for Salmonella and from 0.20 to 0.21 for L. monocytogenes; for STEC, the value was 0.17 kGy. Spinach showed good acceptability, even after exposure to 1.5 kGy. Because gamma radiation reduced the selected pathogens without causing significant changes in the quality of spinach leaves, it may be a useful method to improve safety in the fresh produce industry.
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Affiliation(s)
- Ana Carolina B Rezende
- Food and Experimental Nutrition Department, FCF, University of Sao Paulo, Avenida Professor Lineu Prestes, 580, Bloco 13B, 05508-900, Sao Paulo, SP, Brazil.
| | - Maria Crystina Igarashi
- Food and Experimental Nutrition Department, FCF, University of Sao Paulo, Avenida Professor Lineu Prestes, 580, Bloco 13B, 05508-900, Sao Paulo, SP, Brazil
| | - Maria Teresa Destro
- Food and Experimental Nutrition Department, FCF, University of Sao Paulo, Avenida Professor Lineu Prestes, 580, Bloco 13B, 05508-900, Sao Paulo, SP, Brazil
| | - Bernadette D G M Franco
- Food and Experimental Nutrition Department, FCF, University of Sao Paulo, Avenida Professor Lineu Prestes, 580, Bloco 13B, 05508-900, Sao Paulo, SP, Brazil
| | - Mariza Landgraf
- Food and Experimental Nutrition Department, FCF, University of Sao Paulo, Avenida Professor Lineu Prestes, 580, Bloco 13B, 05508-900, Sao Paulo, SP, Brazil
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22
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Melotto M, Panchal S, Roy D. Plant innate immunity against human bacterial pathogens. Front Microbiol 2014; 5:411. [PMID: 25157245 PMCID: PMC4127659 DOI: 10.3389/fmicb.2014.00411] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 07/21/2014] [Indexed: 11/13/2022] Open
Abstract
Certain human bacterial pathogens such as the enterohemorrhagic Escherichia coli and Salmonella enterica are not proven to be plant pathogens yet. Nonetheless, under certain conditions they can survive on, penetrate into, and colonize internal plant tissues causing serious food borne disease outbreaks. In this review, we highlight current understanding on the molecular mechanisms of plant responses against human bacterial pathogens and discuss salient common and contrasting themes of plant interactions with phytopathogens or human pathogens.
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Affiliation(s)
- Maeli Melotto
- Department of Plant Sciences, University of CaliforniaDavis, CA, USA
| | - Shweta Panchal
- Department of Biology, University of TexasArlington, TX, USA
| | - Debanjana Roy
- Department of Biology, University of TexasArlington, TX, USA
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23
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Lee NY, Kim SW, Ha SD. Synergistic effects of ultrasound and sodium hypochlorite (NaOCl) on reducing Listeria monocytogenes ATCC19118 in broth, stainless steel, and iceberg lettuce. Foodborne Pathog Dis 2014; 11:581-7. [PMID: 24927252 DOI: 10.1089/fpd.2013.1722] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This study was performed in order to determine whether a combined treatment of ultrasound and sodium hypochlorite (NaOCl) is more effective than individual treatment on reducing Listeria monocytogenes ATCC19118 on stainless steel and iceberg lettuce. The bactericidal effect of ultrasound and NaOCl was investigated in tryptic soy broth (TSB), on stainless steel and iceberg lettuce. Various concentrations of NaOCl (50, 100, 150, and 200 ppm) were tested along with various ultrasound treatment times (5, 20, 40, 60, 80, and 100 min). The combined treatment of ultrasound and NaOCl resulted in greater bacterial reductions than either treatment alone, without causing any significant changes in lettuce texture. The synergistic values of combined ultrasound and NaOCl treatments in TSB, on stainless steel, and on iceberg lettuce were 0.01-0.99 log10 colony-forming units (CFU)/mL, 0.01-0.62 log 10 CFU/g, and 0.12-1.66 log10 CFU/g, respectively. These results suggest that the combination of ultrasound and NaOCl was more effective than each treatment against Listeria monocytogenes, and that this combination can effectively sanitize fresh products such as iceberg lettuce.
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Affiliation(s)
- Na-Young Lee
- School of Food Science and Technology, Chung-Ang University , Gyunggido, Korea
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24
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Erickson MC, Webb CC, Davey LE, Payton AS, Flitcroft ID, Doyle MP. Internalization and fate of Escherichia coli O157:H7 in leafy green phyllosphere tissue using various spray conditions. J Food Prot 2014; 77:713-21. [PMID: 24780324 DOI: 10.4315/0362-028x.jfp-13-357] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In the past decade, leafy greens have been implicated in several outbreaks of foodborne illness, and research has focused on contamination during preharvest operations. Concerns have been raised that internalization of pathogens into the edible tissue occurs where postharvest chemical interventions would be ineffective. This study was initiated to measure the degree and fate of Escherichia coli O157:H7 internalized in the phyllosphere tissue of leafy greens when spray conditions, inoculum level, and type of leafy green were varied. Two spraying treatments were applied: (i) spraying individual spinach or lettuce leaves on plants once with a high dose (7 to 8 log CFU/ml) of E. coli O157:H7 and (ii) spraying spinach, lettuce, or parsley plants repeatedly (once per minute) with a low dose (2.7 to 4.2 log CFU/ml) of E. coli O157:H7 over a 10- to 20-min period. With the high-dose spray protocol, no significant differences in the prevalence of internalization occurred between Shiga toxin-negative E. coli O157:H7 isolates and virulent isolates (P > 0.05), implying that the Shiga toxin virulence factors did not influence internalization or the subsequent fate of those populations under these test conditions. Significantly greater internalization of E. coli O157:H7 occurred in spinach leaves compared with lettuce leaves when leaves were sprayed once with the high-dose inoculum (P < 0.05), whereas internalization was not observed in lettuce leaves but continued to be observed in spinach and parsley leaves following repeated spraying of the low-dose inoculum. Based on these results, it is surmised that a moisture film was generated when spraying was repeated and this film assisted in the mobilization of pathogen cells to plant apertures, such as stomata. E. coli O157:H7 cells that were internalized into spinach tissue using a low-dose repeat-spray protocol were temporary residents because they were not detected 2 days later, suggesting that plant-microbe interactions may be responsible.
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Affiliation(s)
- Marilyn C Erickson
- Center for Food Safety, Department of Food Science and Technology, 1109 Experiment Street, Griffin Campus, University of Georgia, Griffin, Georgia 30223, USA.
| | - Cathy C Webb
- Center for Food Safety, Department of Food Science and Technology, 1109 Experiment Street, Griffin Campus, University of Georgia, Griffin, Georgia 30223, USA
| | - Lindsey E Davey
- Center for Food Safety, Department of Food Science and Technology, 1109 Experiment Street, Griffin Campus, University of Georgia, Griffin, Georgia 30223, USA
| | - Alison S Payton
- Center for Food Safety, Department of Food Science and Technology, 1109 Experiment Street, Griffin Campus, University of Georgia, Griffin, Georgia 30223, USA
| | - Ian D Flitcroft
- Department of Crops and Soil Science, 1109 Experiment Street, Griffin Campus, University of Georgia, Griffin, Georgia 30223, USA
| | - Michael P Doyle
- Center for Food Safety, Department of Food Science and Technology, 1109 Experiment Street, Griffin Campus, University of Georgia, Griffin, Georgia 30223, USA
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25
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Moosekian SR, Jeong S, Ryser ET. Inactivation of sanitizer-injured Escherichia coli O157:H7 on baby spinach using X-ray irradiation. Food Control 2014. [DOI: 10.1016/j.foodcont.2013.08.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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26
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Influence of modified atmosphere and varying time in storage on the irradiation sensitivity of Salmonella on sliced roma tomatoes. Radiat Phys Chem Oxf Engl 1993 2013. [DOI: 10.1016/j.radphyschem.2013.04.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Gómez-López VM, Marín A, Allende A, Beuchat LR, Gil MI. Postharvest handling conditions affect internalization of Salmonella in baby spinach during washing. J Food Prot 2013; 76:1145-51. [PMID: 23834788 DOI: 10.4315/0362-028x.jfp-12-539] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Internalization of foodborne pathogens in fruits and vegetables is an increasing safety concern. The aim of this research was to assess the potential for internalization of an enteric pathogen (Salmonella enterica serotype Typhimurium) in a leafy vegetable (baby spinach) during washing as influenced by three postharvest handling conditions: (i) illumination, (ii) negative temperature differential, and (iii) relative humidity (RH). To compare these potential postharvest handling conditions, leaves were exposed to different levels of illumination (0, 1,000, and 2,000 lx), temperature differential (5, 11, 14, 20, and 26°C), and RH (99, 85, and 74%) for a short time before or during washing. Washing of baby spinach was carried out in water containing green fluorescent protein-tagged Salmonella Typhimurium (6.5 log CFU/ml) at 5°C for 2 min, followed by surface disinfection with chlorine (10,000 μg/ml) for 1 min, two rinses in water for 10 s, and spin drying for 15 s. Internalization was assessed by enumerating the pathogen on Salmonella-Shigella agar and by confocal laser scanning microscopy. Illumination of spinach leaves before and during washing and a negative temperature differential during washing did not significantly (P > 0.05) increase the number of internalized bacteria. However, exposure of leaves to low-RH conditions before washing, which reduced the tissue water content, decreased internalization of Salmonella compared with internalization in baby spinach exposed to high RH (P ≤ 0.05). Green fluorescent protein-tagged Salmonella Typhimurium was visualized by confocal laser scanning microscopy at a depth of up to 30 m m beneath the surface of spinach leaves after exposure to a high inoculum level (8 log CFU/ml) for an extended time (2 h). Results show that internalization of Salmonella into baby spinach leaves can occur but can be minimized under specific postharvest handling conditions such as low RH.
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Affiliation(s)
- Vicente M Gómez-López
- Research Group on Quality, Safety and Bioactivity of Plant Foods, Department of Food Science and Technology, CEBAS-CSIC, P.O. Box 164, Espinardo, Murcia, E-30100, Spain
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28
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Gomes Neto NJ, Lucena Pessoa RM, Barbosa Nunes Queiroga IM, Magnani M, de Sousa Freitas FI, de Souza EL, Maciel JF. Bacterial counts and the occurrence of parasites in lettuce (Lactuca sativa) from different cropping systems in Brazil. Food Control 2012. [DOI: 10.1016/j.foodcont.2012.04.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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29
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Jahid IK, Ha SD. A review of microbial biofilms of produce: Future challenge to food safety. Food Sci Biotechnol 2012. [DOI: 10.1007/s10068-012-0041-1] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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30
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Neal JA, Marquez-Gonzalez M, Cabrera-Diaz E, Lucia LM, O'Bryan CA, Crandall PG, Ricke SC, Castillo A. Comparison of multiple chemical sanitizers for reducing Salmonella and Escherichia coli O157:H7 on spinach (Spinacia oleracea) leaves. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.04.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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31
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32
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Faith NG, Waldron T, Czuprynski CJ. Reduction in resident microflora, and experimentally inoculated Salmonella enterica, on spinach leaves treated with vinegar and canola oil. J Food Prot 2012; 75:567-72. [PMID: 22828283 DOI: 10.4315/0362-028x.jfp-11-337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this study, we explored the use of vinegar, or vinegar and canola oil as a salad dressing, to reduce bacterial levels on spinach leaves. We found that incubation of spinach leaves with various types of vinegar substantially reduced the predominantly gram-negative microflora. A similar response was observed when spinach leaves were incubated with white vinegar mixed in various proportions with canola oil, as used in salad dressing. We assessed the effects of vinegar, or vinegar and oil, on spinach leaves that had been experimentally inoculated with a cocktail of Salmonella enterica strains. Allowing the mixture to sit at room temperature for at least 20 min resulted in a substantial reduction (up to 2.0 log CFU) in numbers of S. enterica. Vinegar and oil caused a limited reduction in CFU (0.5 log) for spinach leaves experimentally inoculated with a cocktail of Listeria monocytogenes strains. These findings suggest that mixing spinach leaves with vinegar and oil as a salad dressing can reduce the bacterial load associated with the spinach leaves, including Salmonella if it is present.
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33
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Kim S, Lu L, Chung JH, Lee K, Li Y, Jun S. A microwire sensor for rapid detection of Escherichia coli K-12 in fresh produce. INNOV FOOD SCI EMERG 2011. [DOI: 10.1016/j.ifset.2011.06.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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34
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Niemira BA. Influence of refrigerated storage time on efficacy of irradiation to reduce Salmonella on sliced Roma tomatoes. J Food Prot 2011; 74:990-3. [PMID: 21669078 DOI: 10.4315/0362-028x.jfp-10-385] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Contamination of tomatoes with Salmonella is a recurring food safety concern. Irradiation is a nonthermal intervention that can inactivate pathogens on fresh and minimally processed produce. However, the influence of tomato processing protocols, including time in refrigerated storage and time between slicing and irradiation, has not been determined. Roma tomatoes were sliced and inoculated with a cocktail of Salmonella outbreak strains. The inoculated tomatoes were held in refrigerated storage for various times after inoculation to simulate the potential time delay between packaging and irradiation. Tomatoes were irradiated immediately (0 h) or after 24, 48, or 72 h in storage. The surviving populations were recovered and enumerated. Irradiation effectively reduced Salmonella at all times. The D(10)-values (the dose necessary for a 1-log reduction of the pathogen) were not significantly different at each storage time and ranged from 0.382 to 0.473 kGy. These results suggest that the time required for holding of processed Roma tomatoes or shipment to an off-site irradiation service provider will not alter the efficacy of irradiation in a commercial environment.
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Affiliation(s)
- Brendan A Niemira
- U.S. Department of Agriculture, Agricultural Research Service, Food Safety and Intervention Technologies Research Unit, Eastern Regional Research Center, Wyndmoor, Pennsylvania 19038, USA.
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35
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Fan X, Sokorai KJB. Changes in quality, liking, and purchase intent of irradiated fresh-cut spinach during storage. J Food Sci 2011; 76:S363-8. [PMID: 21623783 DOI: 10.1111/j.1750-3841.2011.02207.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The use of ionizing radiation to enhance microbial safety of fresh spinach at a maximum dose of 4 kGy has been approved by the U.S. Food and Drug Administration (FDA). However, whether spinach can tolerate those high doses of radiation is unclear. Therefore, this study was conducted to investigate the effects of irradiation and storage on quality, liking, and purchase intent of fresh-cut spinach. The oxygen radical absorbance capacity values and total phenolic content were not consistently affected by irradiation. However, the ascorbic acid content of irradiated sample decreased rapidly during storage, resulting in these samples being lower in ascorbic acid content than controls after 7 and 14 d of storage at 4 °C. Sensory evaluation by a 50-member panel revealed that purchase intent and ratings for liking of appearance, aroma, texture, flavor, and overall were not affected by irradiation at doses up to 2 kGy. Therefore, irradiation at doses up to 2 kGy may be used to enhance microbial safety without affecting consumer acceptance or overall antioxidant values of irradiated spinach.
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Affiliation(s)
- Xuetong Fan
- U.S. Dept. of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA.
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36
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Kim HJ, Song HJ, Song KB. Effect of Combined Treatment of Aqueous Chlorine Dioxide with Ultraviolet-C on the Quality of Red Chicory and Pak Choi during Storage. ACTA ACUST UNITED AC 2011. [DOI: 10.3746/jkfn.2011.40.2.245] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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37
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Sodha SV, Lynch M, Wannemuehler K, Leeper M, Malavet M, Schaffzin J, Chen T, Langer A, Glenshaw M, Hoefer D, Dumas N, Lind L, Iwamoto M, Ayers T, Nguyen T, Biggerstaff M, Olson C, Sheth A, Braden C. Multistate outbreak of Escherichia coli O157:H7 infections associated with a national fast-food chain, 2006: a study incorporating epidemiological and food source traceback results. Epidemiol Infect 2011; 139:309-16. [PMID: 20429971 DOI: 10.1017/s0950268810000920] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A multistate outbreak of Escherichia coli O157:H7 infections occurred in the USA in November-December 2006 in patrons of restaurant chain A. We identified 77 cases with chain A exposure in four states - Delaware, New Jersey, New York, and Pennsylvania. Fifty-one (66%) patients were hospitalized, and seven (9%) developed haemolytic uraemic syndrome; none died. In a matched analysis controlling for age in 31 cases and 55 controls, illness was associated with consumption of shredded iceberg lettuce [matched odds ratio (mOR) 8·0, 95% confidence interval (CI) 1·1-348·1] and shredded cheddar cheese (mOR 6·2, CI 1·7-33·7). Lettuce, an uncooked ingredient, was more commonly consumed (97% of patients) than cheddar cheese (84%) and a single source supplied all affected restaurants. A single source of cheese could not explain the regional distribution of outbreak cases. The outbreak highlights challenges in conducting rapid multistate investigations and the importance of incorporating epidemiological study results with other investigative findings.
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Affiliation(s)
- S V Sodha
- Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
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Hsu WY, Simonne A, Jitareerat P, Marshall MR. Low-dose irradiation improves microbial quality and shelf life of fresh mint (Mentha piperita L.) without compromising visual quality. J Food Sci 2010; 75:M222-30. [PMID: 20546414 DOI: 10.1111/j.1750-3841.2010.01568.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
UNLABELLED The effects of low-dose irradiation (0.25 to 2 kGy) and postirradiation storage (at 4 degrees C) on microbial and visual quality, color values (L*, a*, b*, chroma, and hue [ degrees ]), and chlorophyll content (Chl a, Chl b, and total Chl) of fresh mint were evaluated. Samples inoculated with E. coli O157:H7, Salmonella, and MS2 bacteriophage were irradiated and evaluated. E. coli O157:H7 and Salmonella populations were reduced by 2 to 2.4, 3.5, and 5.8 log CFU/g, respectively, 1 d after treatment with 0.25, 0.60, and 1 kGy, respectively, and were completely eliminated at 2 kGy. None of the irradiation doses (P < 0.0001) reduced MS2 bacteriophage populations by more than 0.60 log PFU/g. Irradiation doses did not affect visual quality and samples remained of excellent to good quality (score 7.75 to 9) for up to 9 d of storage. Irradiation at 0.60, 1, and 2 kGy increased (P < 0.0001) Chl a, Chl b, and total Chl. Both total Chl and Chl a decreased significantly after 3 d of storage. Significant decreases in Chl b were not observed until day 12 of storage. Color values (L*, b*, and chroma) were not significantly different until day 6 of storage and hue ( degrees ) remained unchanged (179 degrees ) for the entire storage period of 12 d. Overall, irradiation did not change L*, a*, b*, or chroma. These results demonstrate that irradiation of fresh mint at 2 kGy has the potential to improve its microbial quality and extend its shelf life without compromising its visual quality and color. PRACTICAL APPLICATION Mints and other raw fresh herbs are widely used for flavoring as well as garnish in a variety of dishes without further cooking. However, mint is one considered as one of the high-risk herbs when it comes to microbial contamination. We have evaluated the use of gamma irradiation treatment at very low doses ranging from 0 to 2 kGy to eliminate seeded Salmonella spp, E. coli O157:H7, and MS2 bacteriophage, a surrogate of hepatitis A virus. We found that low-dose irradiation (1.0 to 2.0 kGy) appears to be a promising method for improving the microbiological quality of fresh mint without compromising its visual and color attributes. This method may be applied to many popular fresh culinary herbs that are commonly used as garnishes in Asian cuisine.
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Affiliation(s)
- Wei-Yea Hsu
- Dept. of Family, Youth and Community Sciences, Univ. of Florida, Gainesville, FL 32611-0310, USA
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Neal JA, Booren B, Cisneros-Zevallos L, Miller RK, Lucia LM, Maxim JE, Castillo A. Shelf Life and Sensory Characteristics of Baby Spinach Subjected to Electron Beam Irradiation. J Food Sci 2010; 75:S319-26. [DOI: 10.1111/j.1750-3841.2010.01664.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Berger CN, Sodha SV, Shaw RK, Griffin PM, Pink D, Hand P, Frankel G. Fresh fruit and vegetables as vehicles for the transmission of human pathogens. Environ Microbiol 2010; 12:2385-97. [DOI: 10.1111/j.1462-2920.2010.02297.x] [Citation(s) in RCA: 581] [Impact Index Per Article: 41.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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Niemira BA, Cooke PH. Escherichia coli O157:H7 biofilm formation on Romaine lettuce and spinach leaf surfaces reduces efficacy of irradiation and sodium hypochlorite washes. J Food Sci 2010; 75:M270-7. [PMID: 20629883 DOI: 10.1111/j.1750-3841.2010.01650.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Escherichia coli O157:H7 contamination of leafy green vegetables is an ongoing concern for consumers. Biofilm-associated pathogens are relatively resistant to chemical treatments, but little is known about their response to irradiation. Leaves of Romaine lettuce and baby spinach were dip inoculated with E. coli O157:H7 and stored at 4 degrees C for various times (0, 24, 48, 72 h) to allow biofilms to form. After each time, leaves were treated with either a 3-min wash with a sodium hypochlorite solution (0, 300, or 600 ppm) or increasing doses of irradiation (0, 0.25, 0.5, 0.75, or 1 kGy). Viable bacteria were recovered and enumerated. Chlorine washes were generally only moderately effective, and resulted in maximal reductions of 1.3 log CFU/g for baby spinach and 1.8 log CFU/g for Romaine. Increasing time in storage prior to chemical treatment had no effect on spinach, and had an inconsistent effect on 600 ppm applied to Romaine. Allowing time for formation of biofilm-like aggregations reduced the efficacy of irradiation. D(10) values (the dose required for a 1 log reduction) significantly increased with increasing storage time, up to 48 h postinoculation. From 0 h of storage, D(10) increased from 0.19 kGy to a maximum of 0.40 to 0.43 kGy for Romaine and 0.52 to 0.54 kGy for spinach. SEM showed developing biofilms on both types of leaves during storage. Bacterial colonization of the stomata was extensive on spinach, but not on Romaine. These results indicate that the protection of bacteria on the leaf surface by biofilm formation and stomatal colonization can reduce the antimicrobial efficacy of irradiation on leafy green vegetables.
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Affiliation(s)
- Brendan A Niemira
- Food Safety Intervention Technologies Research Unit, Eastern Regional Research Center, U.S. Dept. of Agriculture, Agricultural Research Service, Wyndmoor, PA 19038, USA.
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Latorre ME, Narvaiz P, Rojas AM, Gerschenson LN. Effects of gamma irradiation on bio-chemical and physico-chemical parameters of fresh-cut red beet (Beta vulgaris L. var. conditiva) root. J FOOD ENG 2010. [DOI: 10.1016/j.jfoodeng.2009.12.024] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Lester GE, Hallman GJ, Pérez JA. gamma-Irradiation dose: effects on baby-leaf spinach ascorbic acid, carotenoids, folate, alpha-tocopherol, and phylloquinone concentrations. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:4901-4906. [PMID: 20329797 DOI: 10.1021/jf100146m] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Ionizing radiation of fruits and vegetables, in the form of gamma rays or electron beams, is effective in overcoming quarantine barriers in trade and prolonging shelf life, but a void of information persists on ionizing radiation effects of vitamin profiles in individual foods. Baby-leaf spinach from commercial cultivars, flat-leafed 'Lazio' and crinkled-leaf 'Samish', was grown, harvested, and surface sanitized according to industry practices. Baby-leaf spinach of each cultivar was packaged under air or N(2) atmosphere, representing industry practices, then exposed to cesium-137 gamma-radiation at 0.0, 0.5, 1.0, 1.5, or 2.0 kGy. Following irradiation, leaf tissues were assayed for vitamin (C, E, K, B(9)) and carotenoid (lutein/zeaxanthin, neoxanthin, violoxanthin, and beta-carotene) concentrations. Atmospheres by irradiation had little consistent effect, but N(2) versus air was associated with elevated dihydroascorbic acid levels. Four phytonutrients (vitamins B(9), E, and K and neoxanthin) exhibited little or no change in concentration with increasing doses of irradiation. However, total ascorbic acid (vitamin C), free ascorbic acid, lutein/zeaxanthin, violaxanthin, and beta-carotene all were significantly reduced at 2.0 kGy and, depending on cultivar, were affected at lesser doses of 0.5 and 1.5 kGy. Dihydroascorbic acid, the most affected compound and an indicator of stress, likely due to irradiation-generated oxidative radicals, increased with increasing irradiation doses >0.5 kGy.
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Affiliation(s)
- Gene E Lester
- Kika de la Garza Subtropical Agricultural Research Center, Agricultural Research Service, U.S. Department of Agriculture, Weslaco, Texas 78596, USA.
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Jeong S, Marks BP, Ryser ET, Moosekian SR. Inactivation of Escherichia coli O157:H7 on lettuce, using low-energy X-ray irradiation. J Food Prot 2010; 73:547-51. [PMID: 20202343 DOI: 10.4315/0362-028x-73.3.547] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Low-energy X-ray irradiation was assessed as a means of eliminating Escherichia coli O157:H7 on lettuce. Round-cut iceberg lettuce samples (2.54-cm diameter) were dip or spot inoculated with a three-strain cocktail of E. coli O157:H7, stored for 24 h at 4 degrees C, and then irradiated at four dose levels up to 0.25 kGy using a prototype low-energy (70 kV) X-ray irradiator. E. coli O157:H7 survivors were quantified by plating on sorbitol MacConkey agar containing cefixime and tellurite. Dip inoculation yielded a D(10)-value of 0.040 +/- 0.001 kGy, which is 3.4 times lower than a previously reported value of 0.136 kGy using gamma radiation. The D(10)-value for E. coli O157:H7 on spot-inoculated samples was 0.078 +/- 0.008 kGy, which is about twice that of dip-inoculated samples. When 10 stacked leaves were irradiated from both sides, a dose of 0.2 kGy was achieved at the center of the stack with a surface dose of 1 kGy, corresponding to a approximately 5-log reduction of E. coli O157:H7 at the center of the stack. Based on these findings, low-energy X-ray irradiation appears to be a promising microbial inactivation strategy for leafy greens and potentially for other types of fresh produce.
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Affiliation(s)
- Sanghyup Jeong
- Biosystems and Agricultural Engineering, Michigan State University, East Lansing, Michigan 48824, USA.
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45
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Kim Y, Choi Y, Kim S, Park J, Chung M, Song KB, Hwang I, Kwon K, Park J. Disinfection of iceberg lettuce by titanium dioxide-UV photocatalytic reaction. J Food Prot 2009; 72:1916-22. [PMID: 19777894 DOI: 10.4315/0362-028x-72.9.1916] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Securing the physical quality and microbial safety of fresh foods has been a major focus in the food industry. To improve quality and increase the shelf life of fresh produce, disinfection methods have been developed. Titanium dioxide (TiO2) photocatalytic reactions under UV radiation produce hydroxyl radicals that can be used for disinfection of foodborne pathogenic bacteria. We investigated the effects of TiO2-UV photocatalytic disinfection on the shelf life of iceberg lettuce. Counts of natural microflora (total aerobic bacteria, coliforms, psychrotrophic bacteria, and yeasts and molds) and inoculated pathogenic bacteria (Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Salmonella Typhimurium) on iceberg lettuce were determined after 20-min treatments with TiO2-UV, UV radiation, a sodium hypochlorite (NaOCl) solution, and tap water. TiO2-UV treatment reduced the number of microorganisms by 1.8 to 2.8 log CFU/g compared with reductions of 0.9 to 1.4 and 0.7 to 1.1 log CFU/g obtained with UV radiation and NaOCl treatments, respectively. Treatment with tap water was used as a control and resulted in no reductions. Counts of microflora for iceberg lettuce at 4 and 25 degrees C were determined during a 9-day period. TiO2-UV treatment resulted in 1.2- and 4.3-log increases in the counts of total aerobic bacteria at 4 and 25 degrees C, respectively, compared with 1.3- to 1.6-log and 4.4- to 4.8-log increases due to UV radiation and NaOCl treatments.
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Affiliation(s)
- Youngbong Kim
- Department of Biotechnology, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea
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Recent advances in the microbial safety of fresh fruits and vegetables. ADVANCES IN FOOD AND NUTRITION RESEARCH 2009; 57:155-208. [PMID: 19595387 DOI: 10.1016/s1043-4526(09)57004-0] [Citation(s) in RCA: 136] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Foodborne illness outbreaks linked to fresh produce are becoming more frequent and widespread. High impact outbreaks, such as that associated with spinach contaminated with Escherichia coli O157:H7, resulted in almost 200 cases of foodborne illness across North America and >$300 m market losses. Over the last decade there has been intensive research into gaining an understanding on the interactions of human pathogens with plants and how microbiological safety of fresh produce can be improved. The following review will provide an update on the food safety issues linked to fresh produce. An overview of recent foodborne illness outbreaks linked to fresh produce. The types of human pathogens encountered will be described and how they can be transferred from their normal animal or human host to fresh produce. The interaction of human pathogens with growing plants will be discussed, in addition to novel intervention methods to enhance the microbiological safety of fresh produce.
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47
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Kim YJ, Lee SH, Park J, Park J, Chung M, Kwon K, Chung K, Won M, Song KB. Inactivation of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes on stored iceberg lettuce by aqueous chlorine dioxide treatment. J Food Sci 2008; 73:M418-22. [PMID: 19021812 DOI: 10.1111/j.1750-3841.2008.00940.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Inactivation of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes in iceberg lettuce by aqueous chlorine dioxide (ClO(2)) treatment was evaluated. Iceberg lettuce samples were inoculated with approximately 7 log CFU/g of E. coli O157:H7, S. typhimurium, and L. monocytogenes. Iceberg lettuce samples were then treated with 0, 5, 10, or 50 ppm ClO(2) solution and stored at 4 degrees C. Aqueous ClO(2) treatment significantly decreased the populations of pathogenic bacteria on shredded lettuce (P < 0.05). In particular, 50 ppm ClO(2) treatment reduced E. coli O157:H7, S. typhimurium, and L. monocytogenes by 1.44, 1.95, and 1.20 log CFU/g, respectively. The D(10)-values of E. coli O157:H7, S. typhimurium, and L. monocytogenes in shredded lettuce were 11, 26, and 42 ppm, respectively. The effect of aqueous ClO(2) treatment on the growth of pathogenic bacteria during storage was evaluated, and a decrease in the population size of these pathogenic bacteria was observed. Additionally, aqueous ClO(2) treatment did not affect the color of lettuce during storage. These results suggest that aqueous ClO(2) treatment can be used to improve the microbial safety of shredded lettuce during storage.
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Affiliation(s)
- Yun-Jung Kim
- Department of Food Science and Technology, Chungnam National University, Daejeon, 305-764, Korea
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48
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Fremaux B, Prigent-Combaret C, Vernozy-Rozand C. Long-term survival of Shiga toxin-producing Escherichia coli in cattle effluents and environment: An updated review. Vet Microbiol 2008; 132:1-18. [DOI: 10.1016/j.vetmic.2008.05.015] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Revised: 05/14/2008] [Accepted: 05/20/2008] [Indexed: 01/01/2023]
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Fan X, Sokorai KJB. Retention of quality and nutritional value of 13 fresh-cut vegetables treated with low-dose radiation. J Food Sci 2008; 73:S367-72. [PMID: 18803730 DOI: 10.1111/j.1750-3841.2008.00871.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Improving the microbial safety while maintaining quality of fresh fruits and vegetables will increase consumer confidence in fresh produce. This study was conducted to investigate the effects of irradiation at 1 kGy, a dose that potentially inactivates E. coli O157:H7 by 5 logs, on the quality of 13 common fresh-cut vegetables: iceberg, romaine, green and red leaf lettuce, spinach, tomato, cilantro, parsley, green onion, carrot, broccoli, red cabbage, and celery. The results showed that the appearance of irradiated samples was similar to the nonirradiated ones except that irradiated carrots, celery, cilantro, and green onions had higher appearance scores than corresponding nonirradiated vegetables. There was no difference in the instrumental texture between irradiated samples and nonirradiated ones. The aroma of several irradiated vegetables was significantly better than controls after 14-d storage, because these control samples decayed or senesced. The 1 kGy irradiation did not affect vitamin C content of most vegetables; however, irradiated green and red leaf lettuce had 24% to 53% lower vitamin C contents than the controls. Our results suggest that most fresh-cut fruits and vegetables tested can tolerate up to 1 kGy irradiation without significant losses in any of the quality attributes.
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Affiliation(s)
- X Fan
- US Dept of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA 19038, USA.
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50
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Niemira BA. Irradiation compared with chlorination for elimination of Escherichia coli O157:H7 internalized in lettuce leaves: influence of lettuce variety. J Food Sci 2008; 73:M208-13. [PMID: 18577002 DOI: 10.1111/j.1750-3841.2008.00746.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Pathogenic bacteria internalized in leaf tissues are not effectively removed by surface treatments. Irradiation has been shown to inactivate leaf-internalized bacteria, but many aspects of targeting these protected pathogens remain unknown. Bacterial cells of a cocktail mixture of 3 isolates of Escherichia coli O157:H7 were drawn into the leaves of iceberg, Boston, green leaf, and red leaf lettuce using vacuum perfusion. The inoculated leaves were treated with a 3-min wash with sodium hypochlorite solution (0, 300, or 600 ppm) or various doses of ionizing radiation (0.25 to 1.5 kGy). Leaves were stomached to recover the internalized cells and survivors enumerated. Washes with 0 ppm (water), 300 ppm, and 600 ppm chlorine solutions each gave reductions of less than 1 log. These reductions were statistically significant only in the case of green leaf lettuce. In contrast, irradiation effectively reduced E. coli O157:H7 on all varieties examined, with all doses tested being significantly reduced from the untreated control. The specific variety influenced the efficacy of irradiation. The greatest reduction obtained was 5 logs on iceberg lettuce treated with 1.5 kGy. The D(10) values (the dose necessary to achieve a 1 log reduction) were significantly (P < 0.05) different among the varieties of lettuce tested, and ranged from 0.30 kGy (iceberg) to 0.45 kGy (Boston). These values were observed to be notably higher than previous irradiation D(10) values for E. coli O157:H7 surface inoculated onto these 4 lettuce varieties. This study has shown that irradiation is able to effectively reduce viable E. coli O157:H7 cells internalized in lettuce, and that the variety of lettuce influences the specific response.
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Affiliation(s)
- B A Niemira
- Food Safety Intervention Technologies Research Unit, Eastern Regional Research Center, U.S. Department of Agriculture, Agricultural Research Service, 600 E. Mermaid Lane, Wyndmoor, PA 19038, USA.
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