Efficacy of Chemical Treatments in Eliminating Salmonella and Escherichia coli O157:H7 on Scarified and Polished Alfalfa Seeds

2001 ◽  
Vol 64 (10) ◽  
pp. 1489-1495 ◽  
Author(s):  
SARAH L. HOLLIDAY ◽  
ALAN J. SCOUTEN ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Chemical Treatment ◽  
Organic Material ◽  
Pathogenic Bacteria ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Mechanical Abrasion ◽  
Chemical Treatments ◽  
The Impact ◽  
Alfalfa Seeds

Alfalfa seeds are sometimes subjected to a scarification treatment to enhance water uptake, which results in more rapid and uniform germination during sprout production. It has been hypothesized that this mechanical abrasion treatment diminishes the efficacy of chemical treatments used to kill or remove pathogenic bacteria from seeds. A study was done to compare the effectiveness of chlorine (20,000 ppm), H2O2 (8%), Ca(OH)2 (1%), Ca(OH)2 (1%) plus Tween 80 (1%), and Ca(OH)2 (1%) plus Span 20 (1%) treatments in killing Salmonella and Escherichia coli O157:H7 inoculated onto control, scarified, and polished alfalfa seeds obtained from two suppliers. The influence of the presence of organic material in the inoculum carrier on the efficacy of sanitizers was investigated. Overall, treatment with 1% Ca(OH)2 was the most effective in reducing populations of the pathogens. Reduction in populations of pathogens on seeds obtained from supplier 1 indicate that chemical treatments are less efficacious in eliminating the pathogens on scarified seeds compared to control seeds. However, the effectiveness of chemical treatment in removing Salmonella and E. coli O157:H7 from seeds obtained from supplier 2 was not markedly affected by scarification or polishing. The presence of organic material in the inoculum carrier did not have a marked influence on the efficacy of chemicals in reducing populations of test pathogens. Additional lots of control, scarified, and polished alfalfa seeds of additional varieties need to be tested before conclusions can be drawn concerning the impact of mechanical abrasion on the efficacy of chemical treatment in removing or killing Salmonella and E. coli O157:H7.

Chemical and Irradiation Treatments for Killing Escherichia coli O157:H7 on Alfalfa, Radish, and Mung Bean Seeds

2003 ◽  
Vol 66 (5) ◽  
pp. 767-774 ◽  
Author(s):  
M. L. BARI ◽  
E. NAZUKA ◽  
Y. SABINA ◽  
S. TODORIKI ◽  
K. ISSHIKI
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Mung Bean ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Chemical Treatments ◽  
Dry Heat ◽  
Pathogen Populations ◽  
Dry Heat Treatment ◽  
Alfalfa Seeds

In this study, the effectiveness of dry-heat treatment in combination with chemical treatments (electrolyzed oxidizing [EO] water, califresh-S, 200 ppm of active chlorinated water) with and without sonication in eliminating Escherichia coli O157:H7 on laboratory-inoculated alfalfa, radish, and mung bean seeds was compared with that of dry-heat treatment in combination with irradiation treatment. The treatment of mung bean seeds with EO water in combination with sonication followed by a rinse with sterile distilled water resulted in reductions of approximately 4.0 log10 CFU of E. coli O157:H7 per g, whereas reductions of ca. 1.52 and 2.64 log10 CFU/g were obtained for radish and alfalfa seeds. The maximum reduction (3.70 log10 CFU/g) for mung bean seeds was achieved by treatment with califresh-S and chlorinated water (200 ppm) in combination with sonication and a rinse. The combination of dry heat, hot EO water treatment, and sonication was able to eliminate pathogen populations on mung bean seeds but was unable to eliminate the pathogen on radish and alfalfa seeds. Other chemical treatments used were effective in greatly reducing pathogen populations on radish and alfalfa seeds without compromising the quality of the sprouts, but these treatments did not result in the elimination of pathogens from radish and alfalfa seeds. Moreover, a combination of dry-heat and irradiation treatments was effective in eliminating E. coli O157:H7 on laboratory-inoculated alfalfa, radish, and mung bean seeds. An irradiation dose of 2.0 kGy in combination with dry heat eliminated E. coli O157:H7 completely from alfalfa and mung bean seeds, whereas a 2.5-kGy dose of irradiation was required to eliminate the pathogen completely from radish seeds. Dry heat in combination with irradiation doses of up to 2.0 kGy did not unacceptably decrease the germination percentage for alfalfa seeds or the length of alfalfa sprouts but did decrease the lengths of radish and mung bean sprouts.

Comparison of Chemical Treatments to Eliminate Enterohemorrhagic Escherichia coli O157:H7 on Alfalfa Seeds

1999 ◽  
Vol 62 (4) ◽  
pp. 318-324 ◽  
Author(s):  
PETER J. TAORMINA ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Germination Percentage ◽  
Enterohemorrhagic Escherichia Coli ◽  
Active Chlorine ◽  
Escherichia Coli O157 ◽  
Dramatic Decrease ◽  
E Coli ◽  
Surfactant Treatment ◽  
Chemical Treatments ◽  
Alfalfa Seeds

The focus of this study was to determine the efficacy of various chemicals in eliminating 2.04 to 3.23 log10 CFU/g of Escherichia coli O157:H7 from alfalfa seeds and to determine the survivability of the pathogen on seeds stored for prolonged periods at three temperatures. Significant (P ≤ 0.05) reductions in populations of E. coli O157:H7 on inoculated seeds were observed after treatments with 500 and 1,000 ppm of active chlorine (as Ca[OCl]2) for 3 but not 10 min and with ≥2,000 ppm of Ca(OCl)2 regardless of pretreatment with a surfactant. Treatment with 20,000 ppm of active chlorine failed to kill 2.68 log10 CFU/g of seeds. Acidified NaClO2 (500 ppm) was effective in reducing populations of the pathogen by >2 logs per g. Acidified ClO2 significantly reduced populations of E. coli O157:H7 on seeds at concentrations ≥100 ppm, and 500 ppm of ClO2 reduced the pathogen from 2.7 log10 CFU/g to <0.5 CFU/g. Chlorine (as NaOCl) was not effective at concentrations ≤1,000 ppm; significant reduction was achieved only after treatment with 2,000 ppm for 3 or 10 min. Notable reduction in populations was observed after treatment with 30 or 70% C2H3OH, but there was a dramatic decrease in germination percentage. Treatment with 0.2% H2O2 significantly reduced populations, and the organism was not detected by direct plating after treatment with ≥1% H2O2. Significant reduction in population of E. coli O157:H7 occurred after treatment with 1% trisodium phosphate, 40 ppm of Tsunami and Vortexx, and 1% Vegi-Clean. A significant decrease in the number of E. coli O157:H7 on dry seeds was observed within 1 week of storage at 25 and 37°C, but not at 5°C. Between 1 and 38 weeks, populations on seeds stored at 5°C remained relatively constant. The pathogen was recovered from alfalfa seeds initially containing 3.04 log10 CFU/g after storage at 25 or 37°C for 38 weeks but not 54 weeks.

Behavior of Enterohemorrhagic Escherichia coli O157:H7 on Alfalfa Sprouts during the Sprouting Process as Influenced by Treatments with Various Chemicals

1999 ◽  
Vol 62 (8) ◽  
pp. 850-856 ◽  
Author(s):  
PETER J. TAORMINA ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Cold Storage ◽  
Treatment Method ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Chemical Treatments ◽  
Alfalfa Sprouts ◽  
Germinated Seeds ◽  
Alfalfa Seeds

The behavior of Escherichia coli O157:H7 on alfalfa seeds subjected to conditions similar to those used commercially to grow and market sprouts as it is affected by applications of NaOCl, Ca(OCl)2, acidified NaClO2, acidified ClO2, Na3PO4, Vegi-Clean, Tsunami, Vortexx, or H2O2 at various stages of the sprouting process was determined. Application of 2,000 ppm of NaOCl, 200 and 2,000 ppm of Ca(OCl)2, 500 ppm of acidified ClO2, 10,000 ppm of Vegi-Clean, 80 ppm of Tsunami, or 40 and 80 ppm of Vortexx to germinated seeds significantly reduced the population of E. coli O157:H7. With the exception of acidified NaOCl2 at 1,200 ppm, spray applications of these chemicals did not significantly reduce populations or control the growth of E. coli O157:H7 on alfalfa sprouts during the sprouting process. Populations of E. coli on alfalfa sprouts peaked at 6 to 7 log10 CFU/g 48 h after initiation of the sprouting process and remained stable despite further spraying with chemicals. The population of E. coli O157:H7 on sprouts as they entered cold storage at 9 ± 2°C remained essentially unchanged for up to 6 days. None of the chemical treatments evaluated was able to eliminate or satisfactorily reduce E. coli O157:H7 on alfalfa seeds and sprouts. Observations on the ability of E. coli O157:H7 to grow during production of alfalfa sprouts not subjected to chemical treatments are similar to those from a previous study in our laboratory on the behavior of Salmonella Stanley. Our results do not reveal a chemical treatment method to eliminate the pathogen from alfalfa sprouts. We have demonstrated that currently recommended procedures for sanitizing alfalfa seeds fail to eliminate E. coli O157:H7 and that the pathogen can grow to populations exceeding 7 log10 CFU/g of sprouts produced using techniques not dissimilar to those used in the sprout industry.

Comparison of Chlorine and a Prototype Produce Wash Product for Effectiveness in Killing Salmonella and Escherichia coli O157:H7 on Alfalfa Seeds

2001 ◽  
Vol 64 (2) ◽  
pp. 152-158 ◽  
Author(s):  
LARRY R. BEUCHAT ◽  
THOMAS E. WARD ◽  
CHARLES A. PETTIGREW
Keyword(s):  
Escherichia Coli ◽  
Human Health ◽  
Organic Material ◽  
Bacterial Pathogens ◽  
Environmental Hazards ◽  
Effective Alternative ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Alfalfa Seeds

Outbreaks of Salmonella and Escherichia coli O157:H7 infections associated with alfalfa and other seed sprouts have occurred with increased frequency in recent years. This study was undertaken to determine the efficacy of a liquid prototype produce wash product (Fit), compared with water and chlorinated water, in killing Salmonella and E. coli O157:H7 inoculated onto alfalfa seeds. We investigated the efficacy of treatments as influenced by seeds from two different lots obtained from two seeds suppliers and by two methods of inoculation. The efficacy of treatments was influenced by differences in seed lots and amount of organic material in the inoculum. Significant (α = 0.05) reductions in Salmonella populations on seeds treated with 20,000 ppm of chlorine or Fit for 30 min ranged from 2.3 to 2.5 log10 CFU/g and 1.7 to 2.3 log10 CFU/g, respectively. Reductions (α = 0.05) in E. coli O157:H7 ranged from 2.0 to 2.1 log10 CFU/g and 1.7 to more than 5.4 log10 CFU/g of seeds treated, respectively, with 20,000 ppm of chlorine or Fit. Compared with treatment with 200 ppm of chlorine, treatment with either 20,000 ppm of chlorine or Fit resulted in significantly higher reductions in populations of Salmonella and E. coli O157:H7. None of the treatments eliminated these pathogens as evidenced by their detection on enrichment of treated seeds. Considering the human health and environmental hazards associated with the use of 20,000 ppm of chlorine, Fit provides an effective alternative to chlorine as a treatment to significantly reduce bacterial pathogens that have been associated with alfalfa seeds.

PCR for the Specific Detection of an Escherichia coli O157:H7 Laboratory Control Strain

2015 ◽  
Vol 78 (9) ◽  
pp. 1738-1744 ◽  
Author(s):  
MICHAEL KNOWLES ◽  
DOMINIC LAMBERT ◽  
GEORGE HUSZCZYNSKI ◽  
MARTINE GAUTHIER ◽  
BURTON W. BLAIS
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Control Measure ◽  
Positive Control ◽  
Food Microbiology ◽  
Escherichia Coli O157 ◽  
Control Strain ◽  
E Coli ◽  
Signature Sequences ◽  
Materials Used

Control strains of bacterial pathogens such as Escherichia coli O157:H7 are commonly processed in parallel with test samples in food microbiology laboratories as a quality control measure to assure the satisfactory performance of materials used in the analytical procedure. Before positive findings can be reported for risk management purposes, analysts must have a means of verifying that pathogenic bacteria (e.g., E. coli O157:H7) recovered from test samples are not due to inadvertent contamination with the control strain routinely handled in the laboratory environment. Here, we report on the application of an in-house bioinformatic pipeline for the identification of unique genomic signature sequences in the development of specific oligonucleotide primers enabling the identification of a common positive control strain, E. coli O157:H7 (ATCC 35150), using a simple PCR procedure.

scholarly journals Impact of Vacuum Cooling on Escherichia coli O157:H7 Infiltration into Lettuce Tissue

2008 ◽  
Vol 74 (10) ◽  
pp. 3138-3142 ◽  
Author(s):  
Haiping Li ◽  
Mehrdad Tajkarimi ◽  
Bennie I. Osburn
Keyword(s):  
Escherichia Coli ◽  
Risk Assessment ◽  
Reduction Rate ◽  
Escherichia Coli O157 ◽  
Surface Sterilization ◽  
E Coli ◽  
Green Industry ◽  
Vacuum Cooling ◽  
The Impact

ABSTRACT Vacuum cooling is a common practice in the California leafy green industry. This study addressed the impact of vacuum cooling on the infiltration of Escherichia coli O157:H7 into lettuce as part of the risk assessment responding to the E. coli O157:H7 outbreaks associated with leafy green produce from California. Vacuum cooling significantly increased the infiltration of E. coli O157:H7 into the lettuce tissue (2.65E+06 CFU/g) compared to the nonvacuumed condition (1.98E+05 CFU/g). A stringent surface sterilization and quadruple washing could not eliminate the internalized bacteria from lettuce. It appeared that vacuuming forcibly changed the structure of lettuce tissue such as the stomata, suggesting a possible mechanism of E. coli O157:H7 internalization. Vacuuming also caused a lower reduction rate of E. coli O157:H7 in stored lettuce leaves than that for the nonvacuumed condition.

scholarly journals The Effect Ultrasound and Surfactants on Nanobubbles Efficacy against Listeria innocua and Escherichia coli O157:H7, in Cell Suspension and on Fresh Produce Surfaces

Foods ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2154
Author(s):  
Shamil Rafeeq ◽  
Reza Ovissipour
Keyword(s):  
Escherichia Coli ◽  
Cell Suspension ◽  
Sodium Dodecyl ◽  
Listeria Innocua ◽  
Wash Water ◽  
Tween 20 ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Bacterial Removal ◽  
The Impact

Removing foodborne pathogens from food surfaces and inactivating them in wash water are critical steps for reducing the number of foodborne illnesses. In this study we evaluated the impact of surfactants on enhancing nanobubbles’ efficacy on Escherichia coli O157:H7, and Listeria innocua removal from spinach leaves. We evaluated the synergistic impact of nanobubbles and ultrasound on these two pathogens inactivation in the cell suspension. The results indicated that nanobubbles or ultrasound alone could not significantly reduce bacteria in cell suspension after 15 min. However, a combination of nanobubbles and ultrasonication caused more than 6 log cfu/mL reduction after 15 min, and 7 log cfu/mL reduction after 10 min of L. innocua and E. coli, respectively. Nanobubbles also enhanced bacterial removal from spinach surface in combination with ultrasonication. Nanobubbles with ultrasound removed more than 2 and 4 log cfu/cm2 of L. innocua and E. coli, respectively, while ultrasound alone caused 0.5 and 1 log cfu/cm2 of L. innocua and E. coli reduction, respectively. No reduction was observed in the solutions with PBS and nanobubbles. Adding food-grade surfactants (0.1% Sodium dodecyl sulfate-SDS, and 0.1% Tween 20), did not significantly enhance nanobubbles efficacy on bacterial removal from spinach surface.

Inactivation of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella in Cranberry, Lemon, and Lime Juice Concentrates

2003 ◽  
Vol 66 (9) ◽  
pp. 1637-1641 ◽  
Author(s):  
MARA C. L. NOGUEIRA ◽  
OMAR A. OYARZÁBAL ◽  
DAVID E. GOMBAS
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Antimicrobial Properties ◽  
Escherichia Coli O157 ◽  
Bacterial Inactivation ◽  
Lime Juice ◽  
E Coli ◽  
Log Reduction ◽  
C 32

The production of thermally concentrated fruit juices uses temperatures high enough to achieve at least a 5-log reduction of pathogenic bacteria that can occur in raw juice. However, the transportation and storage of concentrates at low temperatures prior to final packaging is a common practice in the juice industry and introduces a potential risk for postconcentration contamination with pathogenic bacteria. The present study was undertaken to evaluate the likelihood of Escherichia coli O157: H7, Listeria monocytogenes and Salmonella surviving in cranberry, lemon, and lime juice concentrates at or above temperatures commonly used for transportation or storage of these concentrates. This study demonstrates that cranberry, lemon, and lime juice concentrates possess intrinsic antimicrobial properties that will eliminate these bacterial pathogens in the event of postconcentration recontamination. Bacterial inactivation was demonstrated under all conditions; at least 5-log Salmonella inactivation was consistently demonstrated at −23°C (−10°F), at least 5-log E. coli O157:H7 inactivation was consistently demonstrated at −11°C (12°F), and at least 5-log L. monocytogenes inactivation was consistently demonstrated at 0°C (32°F).

Behavior of Escherichia coli O157:H7 on Damaged Leaves of Spinach, Lettuce, Cilantro, and Parsley Stored at Abusive Temperatures

2010 ◽  
Vol 73 (2) ◽  
pp. 212-220 ◽  
Author(s):  
ROWAIDA K. KHALIL ◽  
JOSEPH F. FRANK
Keyword(s):  
Escherichia Coli ◽  
Pathogenic Bacteria ◽  
Leaf Damage ◽  
Escherichia Coli O157 ◽  
Oxidation Reactions ◽  
Leaf Extracts ◽  
Romaine Lettuce ◽  
Growth And Survival ◽  
E Coli ◽  
Additional Information

Recent foodborne illness outbreaks associated with the consumption of leafy green produce indicates a need for additional information on the behavior of pathogenic bacteria on these products. Previous research indicates that pathogen growth and survival is enhanced by leaf damage. The objective of this study was to compare the behavior of Escherichia coli O157:H7 on damaged leaves of baby Romaine lettuce, spinach, cilantro, and parsley stored at three abusive temperatures (8, 12, and 15°C). The damaged portions of leaves were inoculated with approximately 105 CFU E. coli O157:H7 per leaf. The pathogen grew on damaged spinach leaves held for 3 days at 8 and 12°C (P < 0.05), with the population increasing by 1.18 and 2.08 log CFU per leaf, respectively. E. coli O157:H7 did not grow on damaged Romaine leaves at 8 or 12°C, but growth was observed after 8 h of storage at 15°C, with an increase of less than 1.0 log. Growth of E. coli O157:H7 on Romaine lettuce held at 8 or 12°C was enhanced when inocula were suspended in 0.05% ascorbic acid, indicating the possibility of inhibition by oxidation reactions associated with tissue damage. Damaged cilantro and Italian parsley leaves held at 8°C for 4 days did not support the growth of E. coli O157:H7. Behavior of the pathogen in leaf extracts differed from behavior on the damaged tissue. This study provides evidence that the damaged portion of a leafy green is a distinct growth niche that elicits different microbial responses in the various types of leafy greens.

Inactivation of Pathogenic Bacteria by Cucumber Volatiles (E,Z)-2,6-Nonadienal and (E)-2-Nonenal†

2004 ◽  
Vol 67 (5) ◽  
pp. 1014-1016 ◽  
Author(s):  
M. J. CHO ◽  
R. W. BUESCHER ◽  
M. JOHNSON ◽  
M. JANES
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Bactericidal Activity ◽  
Pathogenic Bacteria ◽  
Brain Heart Infusion ◽  
Escherichia Coli O157 ◽  
Infusion Solution ◽  
E Coli ◽  
Log Reduction

The effects of (E,Z)-2,6-nonadienal (NDE) and (E)-2-nonenal (NE) on Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium were investigated. A suspension of each organism of 6 to 9 log CFU/ml was incubated for 1 h at 37° C in brain heart infusion solution that contained 0 to 500 or 1,000 ppm of NDE or NE. Depending on concentration, exposure to either NDE or NE caused a reduction in CFU of each organism. Treatment with 250 and 500 ppm NDE completely eliminated viable B. cereus and Salmonella Typhimurium cells, respectively. L. monocytogenes was the most resistant to NDE, showing only about a 2-log reduction from exposure to 500 ppm for 1 h. Conversely, this concentration of NDE caused a 5.8-log reduction in E. coli O157:H7 cells. NE was also effective in inactivating organisms listed above. A higher concentration of NE, 1,000 ppm, was required to kill E. coli O157:H7, L. monocytogenes, or Salmonella Typhimurium compared with NDE. In conclusion, both NDE and NE demonstrated an apparent bactericidal activity against these pathogens.

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