Growth and survival of uninjured and sublethally heat-injured Escherichia coli O157:H7 on beef extract medium as influenced by package atmosphere and storage temperature

1999 ◽  
Vol 45 (3) ◽  
pp. 263-268 ◽  
Author(s):  
Jeffrey J Semanchek ◽  
David A Golden ◽  
Robert C Williams
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Storage Temperature ◽  
Brain Heart Infusion ◽  
Escherichia Coli O157 ◽  
Phase Growth ◽  
Growth And Survival ◽  
E Coli ◽  
Beef Extract ◽  
And Storage

The effect of atmospheric composition and storage temperature on growth and survival of uninjured and sublethally heat-injured Escherichia coli O157:H7, inoculated onto brain heart infusion agar containing 0.3% beef extract (BEM), was determined. BEM plates were packaged in barrier bags in air, 100% CO2, 100% N2, 20% CO2 : 80% N2, and vacuum and were stored at 4, 10, and 37°C for up to 20 days. Package atmosphere and inoculum status (i.e., uninjured or heat-injured) influenced (P < 0.01) growth and survival of E. coli O157:H7 stored at all test temperatures. Growth of heat-injured E. coli O157:H7 was slower (P < 0.01) than uninjured E. coli O157:H7 stored at 37°C. At 37°C, uninjured E. coli O157:H7 reached stationary phase growth earlier than heat-injured populations. Uninjured E. coli O157:H7 grew during 10 days of storage at 10°C, while heat-injured populations declined during 20 days of storage at 10°C. Uninjured E. coli O157:H7 stored at 10°C reached stationary phase growth within approximately 10 days in all packaging atmospheres except CO2. Populations of uninjured and heat-injured E. coli O157:H7 declined throughout storage for 20 days at 4°C. Survival of uninjured populations stored at 4°C, as well as heat-injured populations stored at 4 and 10°C, was enhanced in CO2 atmosphere. Survival of heat-injured E. coli O157:H7 at 4 and 10°C was not different (P > 0.05). Uninjured and heat-injured E. coli O157:H7 are able to survive at low temperatures in the modified atmospheres used in this study.Key words: E. coli O157:H7, sublethal injury, modified atmosphere packaging.

Viability of Escherichia coli O157:H7 in Salami Following Conditioning of Batter, Fermentation and Drying of Sticks, and Storage of Slices

1998 ◽  
Vol 61 (4) ◽  
pp. 377-382 ◽  
Author(s):  
NANCY G. FAITH ◽  
NELLY PARNIERE ◽  
TRINA LARSON ◽  
TIMOTHY D. LORANG ◽  
CHARLES W. KASPAR ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Storage Temperature ◽  
Starter Culture ◽  
Escherichia Coli O157 ◽  
Protein Ratio ◽  
E Coli ◽  
Log10 Unit ◽  
Storage Atmosphere ◽  
Unit Reduction ◽  
And Storage

The fate of Escherichia coli O157:H7 was monitored in salami during conditioning of batter, fermentation and drying of sticks, and storage of slices. The raw batter (75% pork:25% beef, wt/wt, fat content about 20%) was inoculated with a pediococcal starter culture (about 108 CFU/g) and a five-strain cocktail of E. coli O157:H7 (≥2 × 107 CFU/g) and stuffed into 104-mm diameter fibrous casings. After being refrigerated at 4°C or being tempered at 13°C, frozen at −20°C, and thawed at 4°C, or being frozen at −20°C, and thawed at 4°C, the inoculated batter was fermented at 24°C and 90% relative humidity (RH) to pH ≤4.8, dried at 13°C and 65% RH to a moisture/protein ratio of ≤1.9:1, and then stored at 4 or 21°C under air or vacuum. For salami sticks sampled immediately after drying, appreciable differences were evident among the various batter-conditioning treatments; pathogen numbers were reduced from original levels by 2.1, 1.6, or 1.1 log10 units when batter was tempered, frozen, and thawed, frozen and thawed, or refrigerated, respectively. Similarly, regardless of storage temperature or atmosphere, within 7 days salami slices cut from sticks prepared from batter that was tempered, frozen, and thawed (2.7- to 4.9-log10-unit reduction) or frozen and thawed (2.3- to 4.8-log10-unit reduction) displayed a greater impact on pathogen numbers than slices cut from sticks prepared from batter that was refrigerated (1.6- to 3.1-log10-unit reduction). The effects of batter conditioning notwithstanding, a greater reduction in levels of E. coli O157:H7 was observed when slices were stored at 21°C compared to otherwise similar slices stored at 4°C. After storage for 60 days the pathogen was only detected by enrichment in slices stored at 21°C, whereas pathogen levels ranged from 1.4 to 4.5 log10 CFU/g in slices stored at 4°C. Differences related to storage atmosphere were first observed after slices were stored for 21 days. Such differences were more readily demonstrable after 60 and 90 days, with pathogen numbers for treatments that were statistically different ranging from 0.6- to 1.5-log10 units higher on slices stored under vacuum than in air. These data emphasize the need to implement multiple barriers to appreciably reduce numbers of E. coli O157:H7 in salami.

Death of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in Garlic Butter as Affected by Storage Temperature

2002 ◽  
Vol 65 (12) ◽  
pp. 1976-1980 ◽  
Author(s):  
BARBARA B. ADLER ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Storage Time ◽  
Storage Temperature ◽  
Rapid Decline ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Pathogen Populations ◽  
And Storage

Garlic is known to have antimicrobial activity against several spoilage and pathogenic bacteria. However, the fate of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in garlic butter has not been reported. This study was undertaken to determine the viability of these organisms in garlic butter as affected by the type of raw minced garlic added to the butter, storage temperature, and storage time. Unsalted butter at 40°C was combined with raw minced jumbo, elephant, or small-cloved garlic at a 4:1 butter/garlic ratio (wt/wt), inoculated with mixed-strain suspensions of Salmonella, E. coli O157:H7, or L. monocytogenes, and stored at 4.4, 21, or 37°C for up to 48 h. All pathogens retained their viability at 4.4°C, regardless of the presence of garlic. The addition of garlic to butter enhanced the rates of inactivation of all three pathogens at 21 and 37°C. The most rapid decline in pathogen populations was observed at 37°C. The inactivation of L. monocytogenes occurred more slowly than did that of Salmonella or E. coli O157:H7. The inactivation of Salmonella and L. monocytogenes was more rapid in jumbo garlic butter than in elephant or small-cloved garlic butter. It is concluded that Salmonella, E. coli O157:H7, and L. monocytogenes did not grow in unsalted butter, with or without garlic added (20%, wt/wt), when inoculated products were stored at 4.4, 21, and 37°C for up to 48 h.

Growth and Survival of Foodborne Pathogens in Beer

2011 ◽  
Vol 74 (10) ◽  
pp. 1670-1675 ◽  
Author(s):  
GARRY MENZ ◽  
PETER ALDRED ◽  
FRANK VRIESEKOOP
Keyword(s):  
Salmonella Typhimurium ◽  
Foodborne Pathogens ◽  
Storage Temperature ◽  
Escherichia Coli O157 ◽  
Gram Negative ◽  
Growth And Survival ◽  
E Coli ◽  
And Storage ◽  
And Staphylococcus Aureus ◽  
Storage Temperatures

This work aimed to assess the growth and survival of four foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus) in beer. The effects of ethanol, pH, and storage temperature were investigated for the gram-negative pathogens (E. coli O157:H7 and Salmonella Typhimurium), whereas the presence of hops ensured that the gram-positive pathogens (L. monocytogenes and S. aureus) were rapidly inactivated in alcohol-free beer. The pathogens E. coli O157:H7 and Salmonella Typhimurium could not grow in the mid-strength or full-strength beers, although they could survive for more than 30 days in the mid-strength beer when held at 4°C. These pathogens grew rapidly in the alcohol-free beer; however, growth was prevented when the pH of the alcohol-free beer was lowered from the “as received” value of 4.3 to 4.0. Pathogen survival in all beers was prolonged at lowered storage temperatures.

Survival of Escherichia coli O157:H7 in Buttermilk as Affected by Contamination Point and Storage Temperature

2000 ◽  
Vol 63 (4) ◽  
pp. 441-444 ◽  
Author(s):  
S. C. McINGVALE ◽  
X. Q. CHEN ◽  
J. L. McKILLIP ◽  
M. A. DRAKE
Keyword(s):  
Escherichia Coli ◽  
Storage Temperature ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
D Values ◽  
And Storage ◽  
Storage Temperatures

The effects of contamination point (during fermentation versus postfermentation) and storage temperature (5 and 12°C) were determined for survival of Escherichia coli O157:H7 in fermented buttermilk. E. coli O157:H7 was recovered from buttermilk inoculated during fermentation for 22 days and in buttermilk inoculated postfermentation for 32 days. For storage temperatures of 5 and 12°C, D-values were lower for E. coli O157:H7 inoculated during fermentation (2.5, 2.2 days) than postfermentation (5.6, 4.8 days) (P &lt; 0.05). Developed acidity in inoculated buttermilks was not different from controls (P &gt; 0.05). The extended recovery of viable enterohemorhagic E. coli O157:H7 from both processing scenarios indicates that the presence of E. coli O157:H7 in buttermilk is not limited to postprocessing contamination.

Effect of Different Levels of Beef Bacterial Microflora on the Growth and Survival of Escherichia coli O157:H7 on Beef Carcass Tissue†

2001 ◽  
Vol 64 (8) ◽  
pp. 1138-1144 ◽  
Author(s):  
ELAINE D. BERRY ◽  
MOHAMMAD KOOHMARAIE
Keyword(s):  
Escherichia Coli ◽  
Viable Cell ◽  
Escherichia Coli O157 ◽  
Growth And Survival ◽  
E Coli ◽  
C Storage ◽  
Additional Control ◽  
Inoculation Treatment ◽  
And Storage ◽  
Different Levels

The influence of various levels of endogenous beef bacterial microflora on the growth and survival of Escherichia coli O157:H7 on bovine carcass surface tissue was investigated. Bacterial beef microflora inoculum was prepared by enriching and harvesting bacteria from prerigor lean bovine carcass tissue (BCT) and was inoculated onto UV-irradiated prerigor BCT at initial levels of 105, 104, 103, and &lt;103 CFU/cm2. Additional control BCT was inoculated with sterile H2O. E. coli O157:H7 was inoculated onto all tissues at an initial level of 102 CFU/cm2. Following a 48-h incubation at 4°C, BCT was incubated up to 14 days at 4 or 12°C, either aerobically or vacuum packaged. Regardless of the microflora level, there was no substantial growth of E. coli O157:H7 on BCT during storage at 4°C under either aerobic or vacuum-packaged conditions. Instead, viable cell numbers at 4°C remained constant, with no reduction in numbers associated with the different beef microflora levels. E. coli O157:H7 grew on all BCT stored at 12°C, regardless of microflora inoculation treatment, reaching higher populations on aerobic samples than on vacuum-packaged samples in 10 days. However, the presence of the beef microflora did appear to delay the onset of growth or slow the growth of the pathogen, and E. coli O157:H7 counts on BCT without added microflora were generally higher following 7 to 10 days of 12°C storage than those counts on BCT inoculated with beef microflora. These data demonstrate the importance of temperature control during meat handling and storage to prevent the outgrowth of this pathogen and indicate that proper sanitation and processing practices that prevent and reduce contamination of carcasses with E. coli O157:H7 are essential, regardless of background microflora levels.

Inactivation of Salmonella Typhimurium and Escherichia coli O157:H7 in Apple Juice by a Combination of Nisin and Cinnamon

2004 ◽  
Vol 67 (2) ◽  
pp. 371-377 ◽  
Author(s):  
J. YUSTE ◽  
D. Y. C. FUNG
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Apple Juice ◽  
Storage Temperature ◽  
Selective Medium ◽  
Escherichia Coli O157 ◽  
Killing Effect ◽  
E Coli ◽  
Agar Layer ◽  
And Storage

Pasteurized apple juice with nisin (0, 25, 50, 100, and 200 ppm, wt/vol) and cinnamon (0 and 0.3%, wt/vol) was inoculated with Salmonella Typhimurium and Escherichia coli O157:H7 at 104 CFU/ml and stored at 5 and 20°C. Counts on tryptic soy agar (TSA), selective medium (xylose lysine desoxycholate agar for Salmonella Typhimurium, and MacConkey sorbitol agar for E. coli O157:H7), and thin agar layer (TAL) were determined at 1 h and 1, 3, 7, and 14 days. The TAL method (selective medium overlaid with TSA) was used for recovery of sublethally injured cells. The pathogens were gradually inactivated by the acidic pH of apple juice. Nisin and cinnamon greatly contributed to the inactivation. The killing effect was more marked at 20°C, with counts in all treated samples being undetectable by direct plating in 3 days for Salmonella Typhimurium and 7 days for E. coli O157:H7. Thus, several factors influenced the decrease in counts: low pH, addition of nisin and cinnamon, and storage temperature. The TAL method was as effective as TSA in recovering injured cells of the pathogens. The combination of nisin and cinnamon accelerates death of Salmonella Typhimurium and E. coli O157:H7 in apple juice and so enhances the safety of the product.

Effects of Water Source, Dilution, Storage, and Bacterial and Fecal Loads on the Efficacy of Electrolyzed Oxidizing Water for the Control of Escherichia coli O157:H7

2004 ◽  
Vol 67 (7) ◽  
pp. 1377-1383 ◽  
Author(s):  
S. M. L. STEVENSON ◽  
S. R. COOK ◽  
S. J. BACH ◽  
T. A. McALLISTER
Keyword(s):  
Escherichia Coli ◽  
Bactericidal Activity ◽  
Storage Temperature ◽  
Uv Light ◽  
Tap Water ◽  
Organic Matter Content ◽  
Water Source ◽  
Deionized Water ◽  
Escherichia Coli O157 ◽  
E Coli

To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 104 CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P &lt; 0.001) their ORP values to &lt;700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 104 CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24°C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P &lt; 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to ≤848 mV. When stored in the dark, the diluted EO waters retained an ORP of &gt;848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4°C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.

Fate of Escherichia coli O157:H7 and Other Coliforms in Commercial Mayonnaise and Refrigerated Salad Dressing

1995 ◽  
Vol 58 (1) ◽  
pp. 13-18 ◽  
Author(s):  
ERROL V. RAGHUBEER ◽  
JIM S. KE ◽  
MICHAEL L. CAMPBELL ◽  
RICHARD S. MEYER
Keyword(s):  
Escherichia Coli ◽  
Storage Temperature ◽  
Enterobacter Aerogenes ◽  
Antimicrobial Effect ◽  
Coliform Bacteria ◽  
Escherichia Coli O157 ◽  
Salad Dressing ◽  
E Coli ◽  
Survival Pattern ◽  
High Level

Commercial mayonnaise and refrigerated ranch salad dressing were inoculated at two levels with two strains of Escherichia coli O157:H7, a non-pathogenic E. coli, and the non-fecal coliform Enterobacter aerogenes. Results showed that at the high inoculation level (&gt;106 colony forming units [CFU]/g) in mayonnaise stored at room temperature (ca. 22°C) both strains of O157:H7 were undetected at 96 h. At the high inoculation level, all strains of coliform bacteria tested survived longer in salad dressing stored at 4°C than in mayonnaise stored at 22°C. The O157:H7 strains were still present at low levels after 17 days. The survival time in the low-level inoculum (104CFU/g) study decreased, but the survival pattern in the two products was similar to that observed in the high-level inoculum study. Slight differences in survival among strains were observed. The greater antimicrobial effect of mayonnaise may be attributable to differences in pH, water activity (aw), nutrients, storage temperature, and the presence of lysozyme in the whole eggs used in the production of commercial mayonnaise. Coliform bacteria survived longer in refrigerated salad dressing than in mayonnaise particularly at the high-level inoculum. Both mayonnaise (pH 3.91) and salad dressing (pH 4.51) did not support the growth of any of the microorganisms even though survival was observed.

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