Influence of Various Commercial Packaging Conditions on Survival of Escherichia coli O157:H7 to Irradiation by Electron Beam Versus Gamma Rays

1999 ◽  
Vol 62 (1) ◽  
pp. 10-15 ◽  
Author(s):  
VERÓNICA LÓPEZ-GONZÁLEZ ◽  
PETER S. MURANO ◽  
ROBERT E. BRENNAN ◽  
ELSA A. MURANO
Keyword(s):  
Escherichia Coli ◽  
Electron Beam ◽  
Gamma Rays ◽  
Low Dose ◽  
Microbial Population ◽  
Escherichia Coli O157 ◽  
Dose Rates ◽  
Polyethylene Bags ◽  
Effect Of Oxygen ◽  
Permeability Rate

Irradiation of ground beef patties inoculated with the organism Escherichia coli O157:H7 was performed either by gamma rays from a cobalt 60 source or by electron beam generated by a linear accelerator. Patties were packaged in one of the following materials: nylon/polyethylene bags, Saran/polyester/polyethylene bags (PM2), or Saran overwrap with a Styrofoam tray inside. Bags were sealed in air or under vacuum and were irradiated at either 5 or −15°C. Average D10 values (dose required to inactivate 90% of a microbial population) ranged from 0.27 to 0.63 kGy, depending on the conditions. Overall, higher D10 values (P < 0.0001) were obtained upon irradiation at −15°C as compared with 5°C. Cells inoculated in samples packaged in PM2 had the highest D10 values, but only if irradiated by electron beam at −15°C (P < 0.001). Since PM2 had the lowest oxygen permeability rate and since the temperature was too low for radicals to migrate easily, these conditions may have minimized the effect of oxygen- and water-derived radicals on microbial survival. Irradiation by gamma rays resulted in higher D10 values (P < 0.047) than irradiation by electron beam, with the highest values being observed at −15°C. Differences may be attributed to dose rate (1.0 kGy/h for gamma, 17 kGy/min for electron beam) since it is possible that, at low dose rates, microbial enzymes may have more time to repair damage to the cell due to irradiation, resulting in higher D10 values.

Effects of Low-Dose, Low-Penetration Electron Beam Irradiation of Chilled Beef Carcass Surface Cuts on Escherichia coli O157:H7 and Meat Quality†

2005 ◽  
Vol 68 (4) ◽  
pp. 666-672 ◽  
Author(s):  
TERRANCE M. ARTHUR ◽  
TOMMY L. WHEELER ◽  
STEVEN D. SHACKELFORD ◽  
JOSEPH M. BOSILEVAC ◽  
XIANGWU NOU ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Electron Beam ◽  
Low Dose ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
Beam Irradiation ◽  
Beam Radiation ◽  
Beef Carcasses ◽  
Antimicrobial Intervention ◽  
Potential Use

Low-dose, low-penetration electron beam (E-beam) irradiation was evaluated for potential use as an antimicrobial intervention on beef carcasses during processing. The objectives of this study were (i) to assess the efficacy of E-beam irradiation to reduce concentrations of Escherichia coli O157:H7 on a large beef surface and (ii) to evaluate the effect of the treatment on the sensory properties of the product. A 1-kGy dose of E-beam radiation reduced E. coli O157:H7 inoculated onto sections of cutaneous trunci at least 4 log CFU/cm2. In assessing organoleptic impact, flank steak was used as the model muscle. Flank steaks with various levels of penetration by radiation (5, 10, 25, 50, and 75%) were evaluated. None of the flank steak sensory attributes were affected (P > 0.05) by any penetration treatment. Ground beef formulations consisting of 100, 50, 25, 10, 5, and 0% surface-irradiated beef were tested. A trained sensory panel did not detect any difference between the control (0%) and either the 5 or 10% treatments. These results suggest that if chilled carcasses were subjected to low-dose E-beam irradiation, aroma and flavor of ground beef would not be impacted. The data presented here indicate that low-dose, low-penetration E-beam irradiation has potential use as an antimicrobial intervention on beef carcasses during processing and minimally impacts the organoleptic qualities of the treated beef products.

Reduction of Escherichia coli O157:H7 and Salmonella on Baby Spinach, Using Electron Beam Radiation

2008 ◽  
Vol 71 (12) ◽  
pp. 2415-2420 ◽  
Author(s):  
JACK A. NEAL ◽  
ELISA CABRERA-DIAZ ◽  
MAYRA MÁRQUEZ-GONZÁLEZ ◽  
JOSEPH E. MAXIM ◽  
ALEJANDRO CASTILLO
Keyword(s):  
Escherichia Coli ◽  
Electron Beam ◽  
Low Dose ◽  
Spinacia Oleracea ◽  
Microbial Populations ◽  
Escherichia Coli O157 ◽  
Beam Radiation ◽  
E Coli ◽  
Electron Beam Radiation ◽  
Multiple Strains

The effect of low-dose electron beam (e-beam) radiation on the reduction of Escherichia coli O157:H7 and Salmonella in spinach was studied. Fresh baby spinach (Spinacia oleracea) was inoculated with a bacterial cocktail containing multiple strains of rifampin-resistant E. coli O157:H7 and rifampin-resistant Salmonella. Inoculated samples were exposed to e-beam radiation from a linear accelerator and tested for counts of both E. coli O157:H7 and Salmonella. Irradiated spinach was also stored for 8 days at 4°C, and counts were made at 2-day intervals to determine if there was any effect of radiation on the survival trend of both pathogens. When no pathogens were detected on plates, additional enrichment plating was conducted to verify total destruction. Respiration rates were measured on spinach samples exposed to e-beam radiation. Each dose of e-beam radiation significantly reduced the numbers of E. coli O157:H7 and Salmonella from initial levels of 7 log CFU/g. Treatment by e-beam radiation at a dose of 0.40 kGy resulted in a reduction in populations of E. coli O157:H7 and Salmonella of 3.7 and 3.4 log cycles, respectively. At 0.70 kGy, both pathogens were reduced by 4 log. All doses above 1.07 kGy showed reductions greater than 6 log and decreased to undetectable levels when stored for 8 days. The respiration rate of spinach showed no changes after irradiation up to 2.1 kGy. These results suggest that low-dose e-beam radiation may be a viable tool for reducing microbial populations or eliminating E. coli O157:H7 and Salmonella from spinach without product damage.

Ovarian Dysfunction in Fetally Irradiated Beagles

1977 ◽  
Vol 35 ◽  
pp. 658-659
Author(s):  
T. M. Seed ◽  
M. H. Sanderson ◽  
D. L. Gutzeit ◽  
T. E. Fritz ◽  
D. V. Tolle ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Low Dose ◽  
Long Term Effects ◽  
Ovarian Dysfunction ◽  
Dose Rates ◽  
Highly Sensitive ◽  
Microscopic Evaluation ◽  
Ovarian Pathology ◽  
Normal Offspring

The developing mammalian fetus is thought to be highly sensitive to ionizing radiation. However, dose, dose-rate relationships are not well established, especially the long term effects of protracted, low-dose exposure. A previous report (1) has indicated that bred beagle bitches exposed to daily doses of 5 to 35 R 60Co gamma rays throughout gestation can produce viable, seemingly normal offspring. Puppies irradiated in utero are distinguishable from controls only by their smaller size, dental abnormalities, and, in adulthood, by their inability to bear young.We report here our preliminary microscopic evaluation of ovarian pathology in young pups continuously irradiated throughout gestation at daily (22 h/day) dose rates of either 0.4, 1.0, 2.5, or 5.0 R/day of gamma rays from an attenuated 60Co source. Pups from non-irradiated bitches served as controls. Experimental animals were evaluated clinically and hematologically (control + 5.0 R/day pups) at regular intervals.

scholarly journals Effect of Electron Beam Irradiation on Survival of Escherichia coli O157:H7 and Salmonella enterica serovar Thyphimurium in Minced Camel Meat during Refrigerated Storage

2019 ◽  
Author(s):  
A. Amiri ◽  
H. Zandi ◽  
H. Mozaffari Khosravi
Keyword(s):  
Escherichia Coli ◽  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Escherichia Coli O157 ◽  
Refrigerated Storage ◽  
Beam Irradiation ◽  
E Coli ◽  
Serovar Typhimurium ◽  
Camel Meat ◽  
Meat Samples

Background: Electron beam irradiation is one of the effective ways to control foodborne pathogens. We evaluated the effect of electron beam irradiation on survival of Escherichia coli O157:H7 and Salmonella enterica serovar Thyphimurium in minced camel meat during refrigerated storage. Methods: The meat samples were inoculated with E. coli O157:H7 and S. enterica serovar Thyphimurium and then irradiated with doses of 0, 1, 2, 3, and 5 kGy. The samples were stored at 4±1 °C and evaluated microbiologically up to 10 days. Data were analyzed using SPSS software version 18. Results: The microbial loads of minced camel meat samples were significantly reduced (p<0.0001) with increasing the dose of irradiation. The most effective dose was 5 kGy that highly reduced S. enterica serovar Typhimurium, and completely destroyed E. coli O157:H7. However, E. coli O157:H7 was more sensitive to electron beam irradiation than S. enterica serovar Typhimurium. Conclusion: Electron beam irradiation effectively reduced the population of both E. coli O157:H7 and S. enterica serovar Typhimurium in minced camel meat in a dose dependent manner.

Electron-beam radiation effects on the structure and properties of polypropylene at low dose rates

2018 ◽  
Vol 29 (6) ◽  
Author(s):  
Heng-Ti Wang ◽  
Hai-Qing Jiang ◽  
Rong-Fang Shen ◽  
Xiao-Jun Ding ◽  
Cong Zhang ◽  
...  
Keyword(s):  
Electron Beam ◽  
Radiation Effects ◽  
Low Dose ◽  
Structure And Properties ◽  
Beam Radiation ◽  
Dose Rates ◽  
Electron Beam Radiation

Thermal Inactivation of Escherichia coli O157:H7 Isolated from Ground Beef and Bovine Feces, and Suitability of Media for Enumeration

1998 ◽  
Vol 61 (3) ◽  
pp. 285-289 ◽  
Author(s):  
M. ROCELLE S. CLAVERO ◽  
LARRY R. BEUCHAT ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Ground Beef ◽  
Treatment Temperature ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Polyethylene Bags ◽  
D Values ◽  
Bovine Feces

Rates of thermal inactivation of five strains of Escherichia coli O157:H7 isolated from ground beef implicated in outbreaks of hemorrhagic colitis and five strains isolated from bovine feces were determined. Ground beef (22% fat, 10 g), inoculated with individual test strains at populations ranging from 6.85 to 7.40 log10 CFU g−1 of beef, was formed into patties (0.3 cm thick and 8.0 cm in diameter) and sealed in polyethylene bags. For each strain and treatment temperature (54.4, 58.9, 62.8, 65.6, or 68.3°C), 6 bags were simultaneously immersed into a recirculating water bath. Viable cells in patties heated for various lengths of time were enumerated by plating diluted samples on sorbitol MacConkey agar supplemented with 4-methylumbelliferyl-β-d-glucuronide (MSMA) and modified eosin methylene blue (MEMB) agar. Regardless of strain or treatment temperature, higher numbers of E. coli O157:H7 cells were generally recovered on MEMB agar than on MSMA, indicating the inferiority of MSMA as a recovery medium for quantitative determination of E. coli O157:H7 cells in heat-processed ground beef. Significantly (P ≤ 0.05) higher D values when enumeration was done using MEMB agar compared with MSMA. Mean D values for combined strain data at 54.4, 58.9, 62.8, and 65.6°C from cultures on MEMB agar were 123.90, 6.47, 0.62, and 0.20 min, respectively, whereas D values of 25.5, 5.21, 0.57, and 0.18 min were obtained at the same temperatures from cultures on MSMA. Results suggest that cooking ground beef patties to an internal temperature of 68.3°C for 40 s will inactivate at least 99.99% of E. coli O157:H7 cells; z values of 4.0 and 5.1°C were calculated from mean D values obtained from MEMB agar and MSMA, respectively, as recovery media. Differences in D values and z values existed among strains but rates of thermal inactivation do not appear to be correlated with the sources of the isolates.

Survival and Growth of Escherichia coli O157:H7 in Unpasteurized and Pasteurized Milk

1997 ◽  
Vol 60 (6) ◽  
pp. 610-613 ◽  
Author(s):  
GUODONG WANG ◽  
TONG ZHAO ◽  
MICHAEL P. DOYLE
Keyword(s):  
Escherichia Coli ◽  
Microbial Population ◽  
Antagonistic Activity ◽  
Escherichia Coli O157 ◽  
Pasteurized Milk ◽  
E Coli ◽  
Milk Samples ◽  
Unpasteurized Milk ◽  
Uremic Syndrome ◽  
Survival And Growth

Escherichia coli O157:H7, which causes hemorrhagic colitis and hemolytic uremic syndrome, has been responsible for several outbreaks associated with consumption of unpasteurized and improperly processed pasteurized milk, and yogurt. Studies were conducted to determine the survival and growth characteristics of this pathogen in unpasteurized milk and pasteurized milk (3.5% fat, 2% fat, skim) at 5,8, 15, and 22°C for up to 28 days. Two levels of inocula (103 and 105 CFU/ml) of a mixture of five nalidixic acid-resistant E. coli O157:H7 strains were used. E. coli O157:H7 did not grow at 5°C and decreased by 1.6 to 2.0 log CFU/ml in 28 days. Growth occurred at 8°C, with an approximately 1- to 2-log CFU/ml increase within the first 4 days. About a 3- to 5-log CFU/ml increase in E. coli O157:H7 populations was observed at 15°C within the first 3 days. In 3 pasteurized milk samples, E. coli O157:H7 continued to grow to populations of greater than 1.0 × 108 CFU/ml at day 7 and remained constant during the remainder of the incubation period. At 22°C, the pH decreased rapidly to less than 4.0 within 4 days and E. coli O157:H7 decreased to undetectable populations within 14 days. E. coli O157:H7 grew more slowly (P &lt; 0.01) in unpasteurized milk, which had a higher initial microbial population, than in pasteurized milks at 8, 15, or 22°C, likely because of antagonistic activity from preexisting bacteria. No significant differences (P&gt; 0.05) in survival or growth of E. coli O157:H7 were observed among the pasteurized milk samples, regardless of fat concentration, at all temperatures throughout the study. The data indicate that temperature abuse during shipping and handling can result in significant growth of E. coli O157:H7. Holding milk at ≤5°C is recommended to prevent growth of this pathogen.

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