Inactivation of Escherichia coli O157:H7 and Other Naturally Occurring Microorganisms in Apple Cider by Electron Beam Irradiation

2004 ◽  
Vol 67 (8) ◽  
pp. 1574-1577 ◽  
Author(s):  
HUI WANG ◽  
CHERYLL A. REITMEIER ◽  
BONITA A. GLATZ
Keyword(s):  
Escherichia Coli ◽  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Escherichia Coli O157 ◽  
Beam Irradiation ◽  
Accelerator Facility ◽  
Apple Cider ◽  
E Coli ◽  
Naturally Occurring ◽  
D Values

Two Escherichia coli O157:H7 strains, SEA 13 B88 gfp 73ec and B6-914 gfp 90ec, together with two bacteria, three yeasts, and two molds that were randomly selected from a collection of microorganisms found on apples or in apple cider, were inoculated into apple cider and subjected to electron beam irradiation at several doses between 0.0 and 2.3 kGy at the Iowa State University Linear Accelerator Facility. The D-values for the E. coli O157:H7 strains ranged between 0.25 and 0.34 kGy; the D-values for most of the normal flora from apples ranged between 0.24 and 0.59 kGy. By taking into account possible variations in treatment conditions, it was calculated that irradiation at 2.47 kGy should achieve a 5-log reduction of E. coli O157:H7 in apple cider at the 95% confidence level. Naturally occurring yeasts might survive such irradiation treatment.

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.

scholarly journals A Structural Study ofEscherichia coliCells Using anIn SituLiquid Chamber TEM Technology

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Yibing Wang ◽  
Xin Chen ◽  
Hongliang Cao ◽  
Chao Deng ◽  
Xiaodan Cao ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Electron Beam ◽  
Aqueous Solutions ◽  
Structural Study ◽  
Electron Beam Irradiation ◽  
Nanometer Scale ◽  
Beam Irradiation ◽  
Nanoscale Structures ◽  
E Coli

Studying cell microstructures and their behaviors under living conditions has been a challenging subject in microbiology. In this work,in situliquid chamber TEM was used to study structures ofEscherichia colicells in aqueous solutions at a nanometer-scale resolution. Most of the cells remained intact under electron beam irradiation, and nanoscale structures were observed during the TEM imaging. The analysis revealed structures of pili surrounding theE. colicells; the movements of the pili in the liquid were also observed during thein situtests. This technology also allowed the observation of features of the nucleoid in theE. colicells. Overall,in situTEM can be applied as a valuable tool to study real-time microscopic structures and processes in microbial cells residing in native aqueous solutions.

Thermal Inactivation of Escherichia coli O157: H7, Salmonella senftenberg, and Enzymes with Potential as Time-Temperature Indicators in Ground Beef

1997 ◽  
Vol 60 (5) ◽  
pp. 471-475 ◽  
Author(s):  
ALICIA ORTA-RAMIREZ ◽  
JAMES F. PRICE ◽  
YIH-CHIH HSU ◽  
GIRIDARAN J. VEERAMUTHU ◽  
JAMIE S. CHERRY-MERRITT ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Triose Phosphate ◽  
Beef Products ◽  
Z Value ◽  
D Values ◽  
Salmonella Senftenberg

The USDA has established processing schedules for beef products based on the destruction of pathogens. Several enzymes have been suggested as potential indicators of heat processing. However, no relationship between the inactivation rates of these enzymes and those of pathogenic microorganisms has been determined. Our objective was to compare the thermal inactivation of Escherichia coli O157:H7 and Salmonella senftenberg to those of endogenous muscle proteins. Inoculated and noninoculated ground beef samples were heated at four temperatures for predetermined intervals of time in thermal-death-time studies. Bacterial counts were determined and enzymes were assayed for residual activity. The D values for E. coli O157:H7 were 46.10, 6.44, 0.43, and 0.12 min at 53, 58, 63, and 68°C, respectively, with a z value of 5.60°C. The D values for S. senftenberg were 53.00, 15.17, 2.08, and 0.22 min at 53, 58, 63, and 68°C, respectively, with a z value of 6.24°C. Apparent D values at 53, 58, 63, and 68°C were 352.93, 26.31, 5.56, and 3.33 min for acid phosphatase; 6968.64, 543.48, 19.61, and 1.40 min for lactate dehydrogenase; and 3870.97, 2678.59, 769.23, and 42.92 min for peroxidase; with z values of 7.41,3.99, and 7.80°C, respectively. Apparent D values at 53, 58, 63, and 66°C were 325.03, 60.07, 3.07, and 1.34 min for phosphoglycerate mutase; 606.72, 89.86, 4.40, and 1.28 min for glyceraldehyde-3-phosphate dehydrogenase; and 153.06, 20.13, 2.25, and 0.74 min for triose phosphate isomerase; with z values of 5.18, 4.71, and 5.56°C, respectively. The temperature dependence of triose phosphate isomerase was similar to those of both E. coli O157 :H7 and S. senftenberg, suggesting that this enzyme could be used as an endogenous time-temperature indicator in beef products.

Survival of Enterohemorrhagic Escherichia coli O157:H7 in Retail Mustard

2001 ◽  
Vol 64 (6) ◽  
pp. 783-787 ◽  
Author(s):  
CAROLYN M. MAYERHAUSER
Keyword(s):  
Escherichia Coli ◽  
Foodborne Illness ◽  
Enterohemorrhagic Escherichia Coli ◽  
Test Strain ◽  
Escherichia Coli O157 ◽  
Time Intervals ◽  
Fermented Sausage ◽  
Apple Cider ◽  
E Coli ◽  
Predetermined Time

Escherichia coli O157:H7 survival in acid foods such as unpasteurized apple cider and fermented sausage is well documented. Researchers have determined that E. coli O157:H7 can survive in refrigerated acid foods for weeks. The potential of acid foods to serve as a vector of E. coli O157:H7 foodborne illness prompted this study to determine the fate of this organism in retail mustard containing acetic acid when stored at room and refrigerated temperatures. Various retail brands of dijon, yellow, and deli style mustard, pH ranging from 3.17 to 3.63, were inoculated individually with three test strains of E. coli O157:H7. Samples were inoculated with approximately 1.0 × 106 CFU/g, incubated at room (25 ± 2.5°C) and refrigerated (5 ± 3°C) temperatures, and assayed for surviving test strains at predetermined time intervals. An aliquot was appropriately diluted and plated using sorbitol MacConkey agar (SMAC). When the test strain was not recoverable by direct plating, the sample was assayed by enrichment in modified tryptic soy broth and recovered using SMAC. Growth of E. coli O157:H7 test strains was inhibited in all retail mustard styles. E. coli O157:H7 was not detected in dijon style mustard beyond 3 h at room and 2 days at refrigerated temperatures. Survival in yellow and deli style mustard was not detected beyond 1 h. Overall, test strain survival was greater at refrigerated than room temperature. Retail mustard demonstrated the ability to eliminate effectively any chance contamination by this organism within hours to days, suggesting that these products are not a likely factor in E. coli O157:H7 foodborne illness.

Efficacy of Selected Acidulants in Pureed Green Beans Inoculated with Pathogens (Escherichia coli O157:H7 and Listeria monocytogenes)

2006 ◽  
Vol 69 (8) ◽  
pp. 1865-1869 ◽  
Author(s):  
AAKASH KHURANA ◽  
GEORGE B. AWUAH ◽  
BRADLEY TAYLOR ◽  
ELENA ENACHE
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Listeria Monocytogenes ◽  
Titratable Acidity ◽  
Combined Effect ◽  
Escherichia Coli O157 ◽  
Green Beans ◽  
E Coli ◽  
Acid Ph ◽  
D Values

Studies were conducted to evaluate the combined effect of selected acidulants (acetic, citric, malic, and phosphoric acid) and heat on foodborne pathogens (Escherichia coli O157:H7 and Listeria monocytogenes) in pureed green beans. To establish a consistent reference point for comparison, the molar concentrations of the acids remained constant while the acid-to-puree ratio, titratable acidity, and undissociated acid were either measured or calculated for a target acidified green beans at a pH of 3.8, 4.2, and 4.6. The D-values at 149°F were used as the criteria for acid efficacy. Generally, acetic acid (puree, pH 3.8 and 4.2) represented the most effective acid with comparatively low D-values irrespective of the target microorganism. A 10-s heating at 149°F inactivated approximately 106 CFU/ml of E. coli O157:H7 in pureed beans at pH 3.8. The efficacy of acetic acid is likely related to the elevated percent titratable acidity, undissociated acid, and acid-to-puree ratio. The effectiveness (which in this study represents the combined effect of acid and heat) of the remaining acids (citric, malic, and phosphoric) at puree pH values of 3.8 and 4.2 were statistically insignificant (α = 0.05). Surprisingly, acetic acid (puree, pH 4.6) appeared to be the least effective as compared to the other acids tested (citric, malic, and phosphoric) especially on E. coli O157:H7 cells, while L. monocytogenes had a similar resistance to all acids at puree pH 4.6. With the exception of citric acid (pH 3.8), acetic acid (pH 4.6), and malic acid (pH 3.8 and 4.6), which were statistically insignificant (P &gt; 0.05), the D-values for L. monocytogenes were statistically different (P ≤ 0.05) and higher than the D-values for E. coli under similar experimental conditions. A conservative process recommendation (referred to as the “safe harbor” process) was found sufficient and applicable to pureed green beans for the pH range studied.

Survival of Escherichia coli O157:H7 in Full- and Reduced-Fat Pepperoni after Manufacture of Sticks, Storage of Slices at 4°C or 21°C under Air and Vacuum, and Baking of Slices on Frozen Pizza at 135, 191 and 246°C

1998 ◽  
Vol 61 (4) ◽  
pp. 383-389 ◽  
Author(s):  
NANCY G. FAITH ◽  
RACHEL K. WIERZBA ◽  
ANNE M. IHNOT ◽  
ANN M. ROERING ◽  
TIMOTHY D. LORANG ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Relative Humidity ◽  
Starter Culture ◽  
Escherichia Coli O157 ◽  
Protein Ratio ◽  
Direct Plating ◽  
E Coli ◽  
Reduced Fat ◽  
Log10 Unit ◽  
D Values

Pepperoni batter was prepared with fat contents of about 15, 20, and 32% (wt/wt) and inoculated with a pediococcal starter culture and ≥2.0 × 107 CFU/g of a five-strain inoculum of Escherichia coli O157:H7. The batter was fermented at 96°F (ca. 36°C) and 85% relative humidity (RH) to pH ≤ 4.8 and then dried at 55°F (ca. 13°C) and 65% RH to a moisture/protein ratio of ≤1.6:1. For storage, slices were packaged under air or vacuum and stored at 39°F (ca. 4°C) and 70°F (ca. 21°C). For baking, frozen slices were placed on retail frozen cheese pizzas that were subsequently baked at 275°F (ca. 135°C), 375°F (ca. 191°C), or 475°F (ca. 246°C) for 0 to 20 min. Appreciable differences related to fat levels were observed after drying; pathogen numbers decreased by 1.04, 1.31 and 1.62 log10 units in sticks prepared from batter at initial fat levels of 15, 20, and 32%, respectively. During storage, the temperature rather than the atmosphere had the greater effect on pathogen numbers, with similar viability observed among the three fat levels tested. At 70°F (ca. 21°C), compared to original levels, pathogen numbers decreased by ≥5.56 and ≥4.53 log10 units within 14 days in slices stored under air and vacuum, respectively, whereas at 39°F (ca. 4°C) numbers decreased by ≤2.43 log10 CFU/g after 60 days of storage under either atmosphere. Baking, as expected, resulted in greater reductions in pathogen numbers as the temperature and/or time of baking increased. However, it was still possible to recover the pathogen by enrichment after baking frozen slices on frozen pizza at 475°F (ca. 246°C) for 10 min or at 375°F (ca. 191°C) for 15 min. The calculated D values for all three temperatures tested increased as the fat content of the batter increased from 15 to 20 to 32%. The present study confirmed that fermentation and drying were sufficient to reduce levels of E. coli O157:H7 in pepperoni sticks by &lt;2.0 log10 CFU/g. Storage of slices for at least 14 days at ambient temperature under air resulted in a &gt;5.5-log10-unit total reduction of the pathogen. Baking slices on frozen pizza for at least 15 min at 475°F (ca. 246°C) or 20 min at 375°F (ca. 191°C) was necessary to reduce pathogen numbers to below detection by both direct plating and enrichment.

Efficacy of Ultraviolet Light for Reducing Escherichia coli O157:H7 in Unpasteurized Apple Cider

2000 ◽  
Vol 63 (5) ◽  
pp. 563-567 ◽  
Author(s):  
J. R. WRIGHT ◽  
S. S. SUMNER ◽  
C. R. HACKNEY ◽  
M. D. PIERSON ◽  
B. W. ZOECKLEIN
Keyword(s):  
Thin Film ◽  
Escherichia Coli ◽  
Uv Light ◽  
Uv Disinfection ◽  
Escherichia Coli O157 ◽  
Apple Cider ◽  
E Coli ◽  
Log Reduction ◽  
Disinfection Unit ◽  
Additional Reduction

This study examined the efficacy of UV light for reducing Escherichia coli O157:H7 in unpasteurized cider. Cider containing a mixture of acid-resistant E. coli O157:H7 (6.3 log CFU/ml) was treated using a thin-film UV disinfection unit at 254 nm. Dosages ranged from 9,402 to 61,005 μW-s/cm2. Treatment significantly reduced E. coli O157:H7 (P ≤ 0.0001). Mean reduction for all treated samples was 3.81 log CFU/ml. Reduction was also affected by the level of background microflora in cider. Results indicate that UV light is effective for reducing this pathogen in cider. However, with the dosages used in this experiment, additional reduction measures are necessary to achieve the required 5-log reduction.

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