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

2009 ◽  
Vol 72 (3) ◽  
pp. 631-636 ◽  
Author(s):  
M. L. BARI ◽  
D. NEI ◽  
K. ENOMOTO ◽  
S. TODORIKI ◽  
S. KAWAMOTO
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Mung Bean ◽  
Germination Rate ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Dry Heat ◽  
Pathogen Populations ◽  
Dry Heat Treatment ◽  
Alfalfa Seeds

In this study, the effectiveness of prolonged dry-heat treatment (50°C) alone or in combination with chemical treatments (1% oxalic acid, 0.03% phytic acid, 50% ethanol, electrolyzed acidic water, and electrolyzed alkaline water) in eliminating Escherichia coli O157:H7 on laboratory-inoculated alfalfa, radish, broccoli, and mung bean seeds was compared with that of dry-heat treatment in combination with irradiation treatment. Dry-heat treatment for 17 or 24 h alone could reduce E. coli O157:H7 numbers to below detectable levels in radish, broccoli, and alfalfa seeds, but was unable to reduce the pathogen numbers to below the detectable level in mung bean seeds. In addition, dry-heat treatment for 17 h plus sanitizer treatments were effective in greatly reducing pathogen populations on radish, broccoli, and alfalfa seeds, without compromising the quality of the sprouts, but these treatments did not eliminate the pathogen from radish and alfalfa seeds. Seventeen hours of dry heat followed by a 1.0-kGy dose of irradiation completely eliminated E. coli O157:H7 from radish and mung bean seeds, whereas only a minimum radiation dose of 0.25 kGy was required to completely eliminate the pathogen from broccoli and alfalfa seeds. Dry heat in combination with radiation doses of up to 1.0 kGy did not negatively impact the seed germination rate or length of alfalfa, broccoli, and radish seeds or the length of alfalfa, broccoli, and radish sprouts, but did decrease the length of mung bean sprouts.

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.

Thermal Inactivation of Salmonella and Escherichia coli O157:H7 on Alfalfa Seeds

2007 ◽  
Vol 70 (7) ◽  
pp. 1698-1703 ◽  
Author(s):  
GUOPING FENG ◽  
JOHN J. CHUREY ◽  
RANDY W. WOROBO
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Thermal Inactivation ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Dry Heat ◽  
Sprouted Seeds ◽  
Alfalfa Sprouts ◽  
Alfalfa Seeds

Alfalfa seeds inoculated with five strains of Salmonella or Escherichia coli O157:H7 were subjected to dry heat at 55°C for up to 8 days. Five-log reductions in Salmonella or E. coli O157:H7 on seeds were observed. No pathogens were detected on the sprouted seeds, which were initially inoculated with ca. 2 log CFU/g of Salmonella or more than 8 log CFU/g of E. coli O157:H7. The percentages of germination of the alfalfa seeds did not significantly decrease after 6 days of heating at 55°C. These results showed that heat treatment of alfalfa seeds at 55°C for up to 6 days was effective in enhancing the safety of alfalfa sprouts without affecting germination significantly.

Inactivation of Escherichia coli O157:H7 on Inoculated Alfalfa Seeds with Ozonated Water and Heat Treatment

2002 ◽  
Vol 65 (3) ◽  
pp. 447-451 ◽  
Author(s):  
RATNA R. SHARMA ◽  
ALI DEMIRCI ◽  
LARRY R. BEUCHAT ◽  
WILLIAM F. FETT
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Contact Time ◽  
Germination Percentage ◽  
Ozone Treatment ◽  
Escherichia Coli O157 ◽  
Alternative Mode ◽  
E Coli ◽  
Alfalfa Seeds ◽  
Ozonated Water

Alfalfa seeds inoculated with a five-strain mixture of Escherichia coli O157:H7 were immersed in water containing 4, 8, 10, and 21 ppm of ozone for 2, 4, 8, 16, 32, and 64 min at 4°C. Direct ozone sparging of seeds in water was used as an alternative mode of ozone treatment. Ozone-sparged seeds were also subsequently exposed to heat treatment at 40, 50, and 60°C for 3 h. Populations of E. coli O157:H7 on untreated and treated seeds were determined by spread plating diluted samples on tryptic soy agar supplemented with 50 μg/ml of nalidixic acid. Since E. coli O157:H7 was released from inoculated seeds during treatment with ozone, the rate of release of cells from inoculated seeds soaked in 0.1% peptone water for up to 64 min was also determined. The overall reduction of E. coli O157:H7 on seeds treated with ozonated water without continuous sparging ranged from 0.40 to 1.75 log10 CFU/g (59.6 to 98.2%), whereas reductions for control seeds were 0.32 to 1.03 log10 CFU/g (51.7 to 90.5%). Treatment with higher ozone concentrations enhanced inactivation, but contact time longer than 8 min did not result in significantly higher reductions (P > 0.05). For seeds treated by ozone sparging, a 1.12-log10 CFU/g (92.1%) reduction was achieved using a 2-min contact time, and a 2.21-log10 CFU/g (99.4%) reduction was achieved with a 64-min contact time. The corresponding reductions for control seeds were 0.71 log10 CFU/g (79.5%) and 2.21 log10 CFU/g (99.4%), respectively. Treatment of ozone-sparged seeds at 60°C for 3 h reduced the population to an undetectable level by direct plating (4 to 4.8 log10 CFU/g), although survivors were detected by enrichment. Ozone did not have a detrimental effect on seed germination percentage.

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.

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.

scholarly journals Evaluation of Aerated Steam Treatment of Alfalfa and Mung Bean Seeds To Eliminate High Levels of Escherichia coli O157:H7 and O178:H12, Salmonella enterica, and Listeria monocytogenes

2013 ◽  
Vol 79 (15) ◽  
pp. 4613-4619 ◽  
Author(s):  
Patrick Studer ◽  
Werner E. Heller ◽  
Jörg Hummerjohann ◽  
David Drissner
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Mung Bean ◽  
Germination Rate ◽  
Steam Treatment ◽  
Heat Sensitivity ◽  
Human Pathogens ◽  
Content Type ◽  
E Coli

ABSTRACTSprouts contaminated with human pathogens are able to cause food-borne diseases due to the favorable growth conditions for bacteria during germination and because of minimal processing steps prior to consumption. We have investigated the potential of hot humid air, i.e., aerated steam, to treat alfalfa and mung bean seeds which have been artificially contaminated withEscherichia coliO157:H7,Salmonella entericasubsp.entericaserovar Weltevreden, andListeria monocytogenesScott A. In addition, a recently collectedE. coliO178:H12 isolate, characterized by a reduced heat sensitivity, was exposed to the treatment described. Populations ofE. coliO157:H7 andS. entericaon alfalfa and mung bean seeds could be completely eliminated by a 300-s treatment with steam at 70 ± 1°C as revealed by enrichment studies.L. monocytogenesandE. coliO178:H12 could not be completely eliminated from artificially inoculated seeds. However, bacterial populations were reduced by more than 5 log CFU/g on alfalfa and by more than 4 log CFU/g on mung bean seeds. The germination rate of mung beans was not affected by the 300-s treatment compared to the germination rate of untreated seeds whereas that of alfalfa seeds was significantly lower by 11.9%. This chemical-free method is an effective alternative to the 20,000-ppm hypochlorite treatment presently recommended by the U.S. Food and Drug Administration (FDA).

scholarly journals Fate of Escherichia coli O157:H7 in Manure-Amended Soil

2002 ◽  
Vol 68 (5) ◽  
pp. 2605-2609 ◽  
Author(s):  
Xiuping Jiang ◽  
Jennie Morgan ◽  
Michael P. Doyle
Keyword(s):  
Escherichia Coli ◽  
Soil Temperature ◽  
Soil Microorganisms ◽  
Soil Samples ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Contributory Factors ◽  
Pathogen Populations ◽  
Antagonistic Interactions ◽  
Amended Soil

ABSTRACT Escherichia coli O157:H7 cells survived for up to 77, >226, and 231 days in manure-amended autoclaved soil held at 5, 15, and 21°C, respectively. Pathogen populations declined more rapidly in manure-amended unautoclaved soil under the same conditions, likely due to antagonistic interactions with indigenous soil microorganisms. E. coli O157:H7 cells were inactivated more rapidly in both autoclaved and unautoclaved soils amended with manure at a ratio of 1 part manure to 10 parts soil at 15 and 21°C than in soil samples containing dilute amounts of manure. The manure-to-soil ratio, soil temperature, and indigenous microorganisms of the soil appear to be contributory factors to the pathogen's survival in manure-amended soil.

Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium DT104, and Listeria monocytogenes on Inoculated Alfalfa Seeds with a Fatty Acid–Based Sanitizer

2006 ◽  
Vol 69 (3) ◽  
pp. 582-590 ◽  
Author(s):  
PASCALE M. PIERRE ◽  
ELLIOT T. RYSER
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Fatty Acid ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Reference Concentration ◽  
Glycerol Monolaurate ◽  
Alfalfa Seeds

Alfalfa seeds were inoculated with a three-strain cocktail of Escherichia coli O157:H7, Salmonella enterica subsp. enterica serovar Typhimurium DT104, or Listeria monocytogenes by immersion to contain ∼6 to 8 log CFU/g and then treated with a fatty acid–based sanitizer containing 250 ppm of peroxyacid, 1,000 ppm of caprylic and capric acids (Emery 658), 1,000 ppm of lactic acid, and 500 ppm of glycerol monolaurate at a reference concentration of 1×. Inoculated seeds were immersed at sanitizer concentrations of 5×, 10×, and 15× for 1, 3, 5, and 10 min and then assessed for pathogen survivors by direct plating. The lowest concentration that decreased all three pathogens by >5 log was 15×. After a 3-min exposure to the 15× concentration, populations of E. coli O157:H7, Salmonella Typhimurium DT104, and L. monocytogenes decreased by >5.45, >5.62, and >6.92 log, respectively, with no sublethal injury and no significant loss in seed germination rate or final sprout yield. The components of this 15× concentration (treatment A) were assessed independently and in various combinations to optimize antimicrobial activity. With inoculated seeds, treatment C (15,000 ppm of Emery 658, 15,000 ppm of lactic acid, and 7,500 ppm of glycerol monolaurate) decreased Salmonella Typhimurium, E. coli O157:H7, and L. monocytogenes by 6.23 and 5.57 log, 4.77 and 6.29 log, and 3.86 and 4.21 log after 3 and 5 min of exposure, respectively. Treatment D (15,000 ppm of Emery 658 and 15,000 ppm of lactic acid) reduced Salmonella Typhimurium by >6.90 log regardless of exposure time and E. coli O157:H7 and L. monocytogenes by 4.60 and >5.18 log and 3.55 and 3.14 log after 3 and 5 min, respectively. No significant differences (P > 0.05) were found between treatments A, C, and D. Overall, treatment D, which contained Emery 658 and lactic acid as active ingredients, reduced E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes populations by 3.55 to >6.90 log and may provide a viable alternative to the recommended 20,000 ppm of chlorine for sanitizing alfalfa seeds.

Effect of Heat Shock and Incubation Atmosphere on Injury and Recovery of Escherichia coli O157:H7

1993 ◽  
Vol 56 (7) ◽  
pp. 568-572 ◽  
Author(s):  
ELSA A. MURANO ◽  
MERLE D. PIERSON
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Heat Shock ◽  
Escherichia Coli O157 ◽  
Toxic Substances ◽  
Anaerobic Conditions ◽  
E Coli ◽  
Heat Treated ◽  
Shock Response ◽  
Cell Components

Escherichia coli serotype O157:H7 cells were grown at 30°C for 6 h and subjected to a heat stress, or heat shock, at 42°C for 5 min. Heat-shocked and nonheat-shocked controls were heat treated at 55°C for up to 60 min. The number of injured cells was significantly higher in heat-shocked cells than in controls, and the rate of release of cell components was higher in heat-shocked cells. Anaerobic plating resulted in higher recovery of injured cells, when compared with aerobic plating, regardless of whether the cells were heat shocked or not. In addition, heat shocking resulted in lower catalase and superoxide dismutase activities when compared with controls. It also resulted in greater survivability after exposure to hydrogen peroxide, suggesting that heat shocking somehow enables the cells to survive exposure to toxic substances in addition to heat. The heat-shock response, coupled with anaerobic conditions, increased the ability of E. coli O157:H7 cells to recover after a heat treatment. Thus, heat shock did not afford protection to the cells against injury, but rather enhanced their ability to recover during storage.

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