Biological Control of Postharvest Decays of Apple Can Prevent Growth of Escherichia coli O157:H7 in Apple Wounds

1999 ◽  
Vol 62 (12) ◽  
pp. 1372-1375 ◽  
Author(s):  
W. J. JANISIEWICZ ◽  
W. S. CONWAY ◽  
B. LEVERENTZ
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Syringae ◽  
Foodborne Pathogens ◽  
Additional Benefit ◽  
Escherichia Coli O157 ◽  
Water Control ◽  
Commercial Formulation ◽  
E Coli ◽  
Golden Delicious ◽  
Fresh Cut

Fresh cells of the antagonist Pseudomonas syringae at 2.4 × 108 CFU/ml inoculated into wounds of ‘Golden Delicious’ apple prevented Escherichia coli O157:H7 (concentrations ranging from 2.4 × 105 to 2.4 × 107 CFU/ml) from growing in the wounds. This occurred when the two microorganisms were co-inoculated or inoculation with E. coli O157:H7 was conducted 1 or 2 days after inoculation with the antagonist. In similar tests, application of the commercial formulation of this antagonist prevented the growth of E. coli O157:H7 in wounds when inoculated 1 or 2 days after application of the antagonist. Populations of E. coli O157:H7 in wounds treated with water (control) before inoculation with this pathogen increased approximately 2 log units during the first 48 h after inoculation. These results indicate that biocontrol agents developed for controlling storage decays of fruits may have the additional benefit of preventing the growth of foodborne pathogens in freshly wounded tissue of intact and fresh-cut fruits.

Quantitative Microbial Risk Assessment for Escherichia coli O157:H7 in Fresh-Cut Lettuce

2017 ◽  
Vol 80 (2) ◽  
pp. 302-311 ◽  
Author(s):  
Hao Pang ◽  
Elisabetta Lambertini ◽  
Robert L. Buchanan ◽  
Donald W. Schaffner ◽  
Abani K. Pradhan
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
The United States ◽  
Intervention Strategies ◽  
Sensitivity Analyses ◽  
Escherichia Coli O157 ◽  
Baseline Model ◽  
Microbial Risk ◽  
E Coli ◽  
Fresh Cut

ABSTRACT Leafy green vegetables, including lettuce, are recognized as potential vehicles for foodborne pathogens such as Escherichia coli O157:H7. Fresh-cut lettuce is potentially at high risk of causing foodborne illnesses, as it is generally consumed without cooking. Quantitative microbial risk assessments (QMRAs) are gaining more attention as an effective tool to assess and control potential risks associated with foodborne pathogens. This study developed a QMRA model for E. coli O157:H7 in fresh-cut lettuce and evaluated the effects of different potential intervention strategies on the reduction of public health risks. The fresh-cut lettuce production and supply chain was modeled from field production, with both irrigation water and soil as initial contamination sources, to consumption at home. The baseline model (with no interventions) predicted a mean probability of 1 illness per 10 million servings and a mean of 2,160 illness cases per year in the United States. All intervention strategies evaluated (chlorine, ultrasound and organic acid, irradiation, bacteriophage, and consumer washing) significantly reduced the estimated mean number of illness cases when compared with the baseline model prediction (from 11.4- to 17.9-fold reduction). Sensitivity analyses indicated that retail and home storage temperature were the most important factors affecting the predicted number of illness cases. The developed QMRA model provided a framework for estimating risk associated with consumption of E. coli O157:H7–contaminated fresh-cut lettuce and can guide the evaluation and development of intervention strategies aimed at reducing such risk.

Survival and Recovery of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on Lettuce and Parsley as Affected by Method of Inoculation, Time between Inoculation and Analysis, and Treatment with Chlorinated Water

2004 ◽  
Vol 67 (6) ◽  
pp. 1092-1103 ◽  
Author(s):  
MEGAN M. LANG ◽  
LINDA J. HARRIS ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Escherichia Coli O157 ◽  
Water Control ◽  
Drying Time ◽  
E Coli ◽  
Iceberg Lettuce ◽  
Spray Inoculation ◽  
Number Of Cells

The effects of method for applying inoculum and of drying time after inoculation on survival and recovery of foodborne pathogens on iceberg lettuce and parsley were studied. Five-strain mixtures of Escherichia coli O157:H7, Salmonella, or Listeria monocytogenes were applied to lettuce and parsley by dip, spot, or spray inoculation methods. Inocula were dried for 2 h at 22°C or for 2 h at 22°C and then 22 h at 4°C before being treated with water (control) or chlorine (200 μg/ml). Significantly higher populations (CFU per lettuce or parsley sample) of E. coli O157:H7 and Salmonella (α = 0.05) were recovered from dip-inoculated produce than from spot- or spray-inoculated produce. This difference was attributed to larger numbers of cells adhering to lettuce and parsley subjected to dip inoculation. Populations of E. coli O157:H7 and Salmonella recovered from lettuce inoculated by spot and spray methods were not significantly different, but populations recovered from spot-inoculated parsley were significantly higher than those recovered from spray-inoculated parsley, even though the number of cells applied was the same. Significantly different numbers of L. monocytogenes were recovered from inoculated lettuce (dip > spray > spot); populations recovered from dip-inoculated parsley were significantly higher than those recovered from spot- or spray-inoculated parsley, which were not significantly different from each other. Populations of pathogens recovered from lettuce and parsley after drying inoculum for 2 h at 22°C were significantly higher than or equal to populations recovered after drying for 2 h at 22°C and then for 22 h at 4°C. Significant differences (water > chlorine) were observed in populations of all pathogens recovered from treated lettuce and parsley, regardless of inoculation method and drying time. It is recommended that spot inoculation with a drying time of 2 h at 22°C followed by 22 h at 4°C be used to determine the efficacy of chlorine and other sanitizers in killing foodborne pathogens on lettuce and parsley.

Evaluation of Inoculation Method and Inoculum Drying Time for Their Effects on Survival and Efficiency of Recovery of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes Inoculated on the Surface of Tomatoes

2004 ◽  
Vol 67 (4) ◽  
pp. 732-741 ◽  
Author(s):  
MEGAN M. LANG ◽  
LINDA J. HARRIS ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Escherichia Coli O157 ◽  
Water Control ◽  
Drying Time ◽  
E Coli ◽  
Inoculation Method ◽  
Spray Inoculation ◽  
Population Sizes

A study was undertaken to evaluate methods for applying inoculum and to examine the effect of inoculum drying time on survival and recovery of foodborne pathogens inoculated onto the surface of raw, ripe tomatoes. Five-strain mixtures of Escherichia coli O157:H7, Salmonella, or Listeria monocytogenes were applied to tomatoes by dip, spot, or spray inoculation methods. Inocula were dried for 1 or 24 h at 22°C before tomatoes were treated with water (control) or chlorine (200 μg/ml). Significantly (α = 0.05) larger populations (CFU per tomato) of E. coli O157:H7 and Salmonella were recovered from dip-inoculated tomatoes than from spot- or spray-inoculated tomatoes. This difference was attributed to larger numbers of cells adhering to tomatoes subjected to dip inoculation. Populations of E. coli O157:H7 and Salmonella recovered from spot- and spray-inoculated tomatoes containing the same initial number of cells were not significantly different. Significantly different L. monocytogenes population sizes were recovered from inoculated tomatoes (dip > spot > spray). Populations of pathogens recovered from tomatoes were significantly larger when inocula were dried for 1 h compared with 24 h. Significant differences (water > chlorine) were observed in the sizes of populations for all pathogens recovered from tomatoes treated with chlorine, regardless of inoculation method or drying time. Results indicate that inoculation method, drying time, and treatment affect survival and/or recovery of foodborne pathogens inoculated onto the surface of tomatoes. We recommend that spot inoculation with a drying time of 24 h at 22°C be used with standard methods to determine the efficacy of chlorine and other sanitizers for killing foodborne pathogens on tomatoes.

Influence of Punctures, Cuts, and Surface Morphologies of Golden Delicious Apples on Penetration and Growth of Escherichia coli O157:H7

2006 ◽  
Vol 69 (2) ◽  
pp. 267-275 ◽  
Author(s):  
PEYMAN FATEMI ◽  
LUKE F. LaBORDE ◽  
JOHN PATTON ◽  
GERALD M. SAPERS ◽  
BASSAM ANNOUS ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Inner Core ◽  
Escherichia Coli O157 ◽  
Depth Of Penetration ◽  
E Coli ◽  
Effective Strategies ◽  
Golden Delicious ◽  
Fresh Cut ◽  
Morphological Differences ◽  
Surface Morphologies

The ability of Escherichia coli O157:H7 to penetrate and grow within punctures, fresh-cut surfaces, and calyces of Golden Delicious apples was investigated. A three-strain cocktail of E. coli O157:H7 resistant to ampicillin was used to inoculate fresh and 48-h-old punctures, fresh-cut surfaces, and open or closed calyces. A concentric cutting procedure was used to evaluate depth of penetration within punctures and prevent cross contamination during sampling. Within 2 h, E. coli O157: H7 penetrated vertically through the fresh punctures and 3.4 mm within the underlying parenchyma. After 48 h, E. coli O157: H7 cells penetrated up to 5.5 mm within the punctures and >2.6 mm horizontally away from fresh punctures. However, 48-h-old punctures did not permit penetration beyond their boundaries. Fresh-cut surfaces permitted up to 2.8 mm penetration after 24 h. Onset of growth of E. coli O157:H7 occurred 4 to 8 h postinoculation on fresh punctures and fresh-cut surfaces with populations increasing by 3 logs after 48 h. E. coli O157:H7 penetrated within calyces regardless of the extent of opening or method of inoculation. However, E. coli O157:H7 was never recovered from the inner core of apples. Computed tomography scan imaging revealed that closed calyces effectively prevented penetration of sodium iodide solutions within the calyx cavity. Lack of solution penetration may explain why sanitizing treatments are ineffective in inactivating microbial cells within the calyx. Understanding the role of morphological differences in permitting or restricting bacterial penetration may lead to development of more effective strategies to enhance the safety of fresh horticultural products.

Tracking an Escherichia coli O157:H7–Contaminated Batch of Leafy Greens through a Pilot-Scale Fresh-Cut Processing Line

2014 ◽  
Vol 77 (9) ◽  
pp. 1487-1494 ◽  
Author(s):  
ANNEMARIE L. BUCHHOLZ ◽  
GORDON R. DAVIDSON ◽  
BRADLEY P. MARKS ◽  
EWEN C. D. TODD ◽  
ELLIOT T. RYSER
Keyword(s):  
Escherichia Coli ◽  
Membrane Filtration ◽  
Fluorescent Protein ◽  
Pilot Scale ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Leafy Greens ◽  
Iceberg Lettuce ◽  
Processing Line ◽  
Fresh Cut

Cross-contamination of fresh-cut leafy greens with residual Escherichia coli O157:H7–contaminated product during commercial processing was likely a contributing factor in several recent multistate outbreaks. Consequently, radicchio was used as a visual marker to track the spread of the contaminated product to iceberg lettuce in a pilot-scale processing line that included a commercial shredder, step conveyor, flume tank, shaker table, and centrifugal dryer. Uninoculated iceberg lettuce (45 kg) was processed, followed by 9.1 kg of radicchio (dip inoculated to contain a four-strain, green fluorescent protein–labeled nontoxigenic E. coli O157:H7 cocktail at 106 CFU/g) and 907 kg (2,000 lb) of uninoculated iceberg lettuce. After collecting the lettuce and radicchio in about 40 bags (~22.7 kg per bag) along with water and equipment surface samples, all visible shreds of radicchio were retrieved from the bags of shredded product, the equipment, and the floor. E. coli O157:H7 populations were quantified in the lettuce, water, and equipment samples by direct plating with or without prior membrane filtration on Trypticase soy agar containing 0.6% yeast extract and 100 ppm of ampicillin. Based on triplicate experiments, the weight of radicchio in the shredded lettuce averaged 614.9 g (93.6%), 6.9 g (1.3%), 5.0 g (0.8%), and 2.8 g (0.5%) for bags 1 to 10, 11 to 20, 21 to 30, and 31 to 40, respectively, with mean E. coli O157:H7 populations of 1.7, 1.2, 1.1, and 1.1 log CFU/g in radicchio-free lettuce. After processing, more radicchio remained on the conveyor (9.8 g; P < 0.05), compared with the shredder (8.3 g), flume tank (3.5 g), and shaker table (0.1 g), with similar E. coli O157:H7 populations (P > 0.05) recovered from all equipment surfaces after processing. These findings clearly demonstrate both the potential for the continuous spread of contaminated lettuce to multiple batches of product during processing and the need for improved equipment designs that minimize the buildup of residual product during processing.

Reduction of Escherichia coli O157:H7 Counts on Whole Fresh Apples by Treatment with Sanitizers

2000 ◽  
Vol 63 (6) ◽  
pp. 703-708 ◽  
Author(s):  
MARCY A. WISNIEWSKY ◽  
BONITA A. GLATZ ◽  
MARK L. GLEASON ◽  
CHERYLL A. REITMEIER
Keyword(s):  
Escherichia Coli ◽  
Chlorine Dioxide ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Escherichia Coli O157 ◽  
Peroxyacetic Acid ◽  
Water Control ◽  
Buffer Solution ◽  
E Coli ◽  
Log Reduction

The objectives of this study were to determine if washing of whole apples with solutions of three different sanitizers (peroxyacetic acid, chlorine dioxide, or a chlorine-phosphate buffer solution) could reduce a contaminating nonpathogenic Escherichia coli O157:H7 population by 5 logs and at what sanitizer concentration and wash time such a reduction could be achieved. Sanitizers were tested at 1, 2, 4, 8, and 16 times the manufacturer's recommended concentration at wash times of 5, 10, and 15 min. Whole, sound Braeburn apples were inoculated with approximately 1 × 108 or 7 × 106 CFU per apple, stored for 24 h, then washed with sterile water (control) or with sanitizers for the prescribed time. Recovered bacteria were enumerated on trypticase soy agar. Washing with water alone reduced the recoverable population by almost 2 logs from the starting population; this can be attributed to physical removal of organisms from the apple surface. No sanitizer, when used at the recommended concentration, reduced the recovered E. coli population by 5 logs under the test conditions. The most effective sanitizer, peroxyacetic acid, achieved a 5-log reduction when used at 2.1 to 14 times its recommended concentration, depending on the length of the wash time. The chlorine-phosphate buffer solution reduced the population by 5 logs when used at 3 to 15 times its recommended concentration, depending on wash time. At no concentration or wash time tested did chlorine dioxide achieve the 5-log reduction.

Evaluation of Gaseous Chlorine Dioxide as a Sanitizer for Killing Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, and Yeasts and Molds on Fresh and Fresh-Cut Produce

2005 ◽  
Vol 68 (6) ◽  
pp. 1176-1187 ◽  
Author(s):  
KAYE V. SY ◽  
MELINDA B. MURRAY ◽  
M. DAVID HARRISON ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Chlorine Dioxide ◽  
Foodborne Pathogens ◽  
Escherichia Coli O157 ◽  
Gaseous Chlorine Dioxide ◽  
Sensory Qualities ◽  
A Cell ◽  
Fresh Cut ◽  
Yeasts And Molds

Gaseous chlorine dioxide (ClO2) was evaluated for effectiveness in killing Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes on fresh-cut lettuce, cabbage, and carrot and Salmonella, yeasts, and molds on apples, peaches, tomatoes, and onions. Inoculum (100 μl, ca. 6.8 log CFU) containing five serotypes of Salmonella enterica, five strains of E. coli O157:H7, or five strains of L. monocytogenes was deposited on the skin and cut surfaces of fresh-cut vegetables, dried for 30 min at 22°C, held for 20 h at 4°C, and then incubated for 30 min at 22°C before treatment. The skin surfaces of apples, peaches, tomatoes, and onions were inoculated with 100 μl of a cell suspension (ca. 8.0 log CFU) containing five serotypes of Salmonella, and inoculated produce was allowed to dry for 20 to 22 h at 22°C before treatment. Treatment with ClO2 at 4.1 mg/liter significantly (α = 0.05) reduced the population of foodborne pathogens on all produce. Reductions resulting from this treatment were 3.13 to 4.42 log CFU/g for fresh-cut cabbage, 5.15 to 5.88 log CFU/g for fresh-cut carrots, 1.53 to 1.58 log CFU/g for fresh-cut lettuce, 4.21 log CFU per apple, 4.33 log CFU per tomato, 1.94 log CFU per onion, and 3.23 log CFU per peach. The highest reductions in yeast and mold populations resulting from the same treatment were 1.68 log CFU per apple and 2.65 log CFU per peach. Populations of yeasts and molds on tomatoes and onions were not significantly reduced by treatment with 4.1 mg/liter ClO2. Substantial reductions in populations of pathogens on apples, tomatoes, and onions but not peaches or fresh-cut cabbage, carrot, and lettuce were achieved by treatment with gaseous ClO2 without markedly adverse effects on sensory qualities.

Contamination of Intact Apples after Immersion in an Aqueous Environment Containing Escherichia coli O157:H7†

1999 ◽  
Vol 62 (5) ◽  
pp. 444-450 ◽  
Author(s):  
R. L. BUCHANAN ◽  
S. G. EDELSON ◽  
R. L. MILLER ◽  
G. M. SAPERS
Keyword(s):  
Escherichia Coli ◽  
Outer Core ◽  
Core Region ◽  
Effect Of Temperature ◽  
Aqueous Environment ◽  
Escherichia Coli O157 ◽  
Dye Uptake ◽  
E Coli ◽  
Golden Delicious ◽  
Peptone Water

The extent and location of Escherichia coli O157:H7 contamination after intact apples were immersed in cold (2°C) 1% peptone water containing approximately 3 × 107 CFU/ml was assessed using four apple varieties, Golden Delicious, McIntosh, Red Delicious, and Braeburn. Room temperature and refrigerated apples were used to determine the effect of temperature differential on E. coli infiltration. The highest levels of E. coli were associated with the outer core region of the apple, followed by the skin. Apples were subsequently treated by immersing them for 1 min in 2,000 mg/liter sodium hypochlorite, followed by a 1-min tapwater rinse. This treatment reduced pathogen levels by 1- to 3-log cycles but did not eliminate the microorganism, particularly from the outer core region. While E. coli was not detected in the inner core of most apples, warm fruit immersed in cold peptone water occasionally internalized the pathogen. The frequency and extent of internalization of the pathogen was less when cold apples were immersed in cold peptone water. Subsequent dye uptake studies with Golden Delicious apples indicated that approximately 6% of warm apples immersed into a cold dye solution accumulated dye via open channels leading from the blossom end into the core region. However, dye uptake did not occur when the dye solution was warmer than the apple.

scholarly journals Growth of Salmonella and Other Foodborne Pathogens on Inoculated Inshell Pistachios during Simulated Delays between Hulling and Drying

2019 ◽  
Vol 82 (5) ◽  
pp. 815-825 ◽  
Author(s):  
MAHTA MOUSSAVI ◽  
VANESSA LIEBERMAN ◽  
CHRIS THEOFEL ◽  
JAVAD BAROUEI ◽  
LINDA J. HARRIS
Keyword(s):  
Escherichia Coli ◽  
Relative Humidity ◽  
Foodborne Pathogens ◽  
Lag Time ◽  
Escherichia Coli O157 ◽  
Contributing Factors ◽  
Shell Surface ◽  
E Coli ◽  
Significant Growth ◽  
Lower Maximum

ABSTRACT During harvest, pistachios are hulled, separated in water into floater and sinker streams (in large part on the basis of nut density), and then dried before storage. Higher prevalence and levels of Salmonella were previously observed in floater pistachios, but contributing factors are unclear. To examine the behavior of pathogens on hulled pistachios during simulated drying delays, floater and sinker pistachios collected from commercial processors were inoculated at 1 or 3 log CFU/g with cocktails of Salmonella and in some cases Escherichia coli O157:H7 or Listeria monocytogenes and incubated for up to 30 h at 37°C and 90% relative humidity. Populations were measured by plating onto tryptic soy agar and appropriate selective agars. In most cases, no significant growth (P > 0.05) of Salmonella was observed in the first 3 h after inoculation in hulled floaters and sinkers. Growth of Salmonella was greater on floater pistachios than on corresponding sinkers and on floater pistachios with ≥25% hull adhering to the shell surface than on corresponding floaters with <25% adhering hull. Maximum Salmonella populations (2 to 7 log CFU/g) were ∼2-log higher on floaters than on corresponding sinkers. The growth of E. coli O157:H7 and Salmonella on hulled pistachios was similar, but a longer lag time (approximately 11 h) and significantly lower maximum populations (4 versus 5 to 6 log CFU/g; P < 0.05) were predicted for L. monocytogenes. Significant growth of pathogens on hulled pistachios is possible when delays between hulling and drying are longer than 3 h, and pathogen growth is enhanced in the presence of adhering hull material.

Inactivation of Escherichia coli O157:H7 and Salmonella and Native Microbiota on Fresh Strawberries by Antimicrobial Washing and Coating

2018 ◽  
Vol 81 (8) ◽  
pp. 1227-1235 ◽  
Author(s):  
MINGMING GUO ◽  
TONY Z. JIN ◽  
JOSHUA B. GURTLER ◽  
XUETONG FAN ◽  
MADHAV P. YADAV
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Allyl Isothiocyanate ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Native Microflora ◽  
Pathogen Populations ◽  
Antimicrobial Treatments ◽  
Antimicrobial Effectiveness

ABSTRACT Antimicrobial washing (AW), antimicrobial coating (AC), and a combination of washing followed by coating (AW+AC) were evaluated for their ability to inactivate artificially inoculated foodborne pathogens and native microbiota on strawberries stored at 4°C. Strawberries were inoculated with a six-strain composite of Escherichia coli O157:H7 and Salmonella; treated by AW, AC, or AW+AC; and stored at 4°C for 3 weeks. The washing solution contained 90 ppm of peracetic acid, and the coating solution consisted of chitosan (1%, w/v), allyl isothiocyanate (1%, v/v), and corn-bio fiber gum (5%, w/v). The effectiveness of the antimicrobial treatments against E. coli O157:H7 and Salmonella pathogens and native microflora on strawberries and their impact on fruit quality (appearance, weight loss, color, and firmness) were determined. By the end of storage, pathogen populations on strawberries were 2.5 (AW+AC), 2.9 (AC), 3.8 (AW), and 4.2 log CFU for the positive (untreated) control. AW+AC treatments also inactivated the greatest population of native microflora, followed by the AC treatment alone. AW+AC treatments showed additional antimicrobial effectiveness against these two pathogens and native microflora. Both AW+AC and AC treatments preserved the color, texture, and appearance of strawberries throughout storage. The coating treatments (AW+AC and AC alone) further reduced the loss of moisture throughout storage. The AW treatment was the least effective in reducing populations of pathogens and native microflora and in maintaining the quality of strawberries throughout storage. This study demonstrates a method to improve the microbiological safety, shelf life, and quality of strawberries.

Sign in / Sign up

Export Citation Format

Share Document