Thermal Destruction of Escherichia coli O157:H7 in Hamburger†

The inactivation of E. coli O157:H7 in ground beef patties cooked in a skillet was investigated. Ground beef patties inoculated with a mixture of five strains of E. coli O157:H7 were cooked in a Farberware skillet set at a temperature of 275°F (137°C). Eight type K thermocouples connected to a data logger were used to record the temperatures at eight points within the patty. The cooking times studied ranged from 2.25 min to 4 min. Tryptic soy agar plates overlaid with sorbitol MacConkey agar were used for recovery of E. coli O157:H7. Heating of ground beef patties to an internal temperature endpoint of 155°F (68.3°C) resulted in 4-log cycle reductions of the organism. The results of this investigation conducted under conditions simulating those that occur in the retail food industry provide a basis for ensuring safety against E. coli O157:H7 in ground beef patties.

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Survival of Escherichia coli O157:H7 in Ground-Beef Patties during Storage at 2, −2, 15 and then −2°C, and −20°C†

Journal of Food Protection ◽

10.4315/0362-028x-62.11.1243 ◽

1999 ◽

Vol 62 (11) ◽

pp. 1243-1247 ◽

Cited By ~ 37

Author(s):

SUSAN E. ANSAY ◽

KIM A. DARLING ◽

CHARLES W. KASPAR

Keyword(s):

Escherichia Coli ◽

Frozen Storage ◽

Ground Beef ◽

Plate Count ◽

Escherichia Coli O157 ◽

Control Strain ◽

Single Strain ◽

E Coli ◽

Beef Patties ◽

Significant Difference

The survival of Escherichia coli O157:H7 and of a nonpathogenic control strain of E. coli was monitored in raw ground beef that was stored at 2°C for 4 weeks, −2°C for 4 weeks, 15°C for 4 h and then −2°C for 4 weeks, and −20°C. Irradiated ground beef was inoculated with one E. coli control strain or with a four-strain cocktail of E. coli O157:H7 (ca. 105 CFU/g), formed into patties (30 to 45 g), and stored at the appropriate temperature. The numbers of the E. coli control strain decreased by 1.4 log10 CFU/g, and pathogen numbers declined 1.9 log10 CFU/g when patties were stored for 4 weeks at 2°C. When patties were stored at −2°C for 4 weeks, the numbers of the E. coli control strain and the serotype O157:H7 strains decreased 2.8 and 1.5 log10 CFU/g, respectively. Patties stored at 15°C for 4 h prior to storage at −2°C for 4 weeks resulted in 1.6 and 2.7 log10–CFU/g reduction in the numbers of E. coli and E. coli O157:H7, respectively. Storage of retail ground beef at 15°C for 4 h (tempering) did not result in increased numbers of colony forming units per gram, as determined with violet red bile, MRS lactobacilli, and plate-count agars. Frozen storage (−20°C) of ground-beef patties that had been inoculated with a single strain of E. coli resulted in approximately a 1 to 2 log10–CFU/g reduction in the numbers of the control strain and individual serotype O157:H7 strains after 1 year. There was no significant difference between the survival of the control strain and the O157:H7 strains, nor was there a difference between O157:H7 strains. These data demonstrate that tempering of ground-beef patties prior to low-temperature storage accelerated the decline in the numbers of E. coli O157:H7.

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Inactivation of Escherichia coli O157:H7 in Ground Beef by Single-Cycle and Multiple-Cycle High-Pressure Treatments

Journal of Food Protection ◽

10.4315/0362-028x-71.4.811 ◽

2008 ◽

Vol 71 (4) ◽

pp. 811-815 ◽

Cited By ~ 37

Author(s):

PILAR MORALES ◽

JAVIER CALZADA ◽

MARTA ÁVILA ◽

MANUEL NUÑEZ

Keyword(s):

Escherichia Coli ◽

High Pressure ◽

Shear Force ◽

Ground Beef ◽

Escherichia Coli O157 ◽

Single Cycle ◽

E Coli ◽

Beef Patties ◽

Texture Parameters ◽

Multiple Cycle

The effect of single- and multiple-cycle high-pressure treatments on the survival of Escherichia coli CECT 4972, a strain belonging to the O157:H7 serotype, in ground beef was investigated. Beef patties were inoculated with 107 CFU/g E. coli O157:H7, and held at 4°C for 20 h before high-pressure treatments. Reduction of the E. coli O157:H7 population by single-cycle treatments at 400 MPa and 12°C ranged from 0.82 log CFU/g for a 1-min cycle to 4.39 log CFU/g for a 20-min cycle. Multiple-cycle treatments were very effective, with four 1-min cycles at 400 MPa and 12°C reducing the E. coli O157:H7 population by 4.38 log CFU/g, and three 5-min cycles by 4.96 log CFU/g. The color parameter L* increased significantly with high-pressure treatments in the interior and the exterior of beef patties, whereas a* decreased in the interior, and b* increased in the exterior—changes that might diminish consumer acceptance of the product. Kramer shear force and energy were generally higher in pressurized than in control ground beef. Maximum values for these texture parameters, which corresponded to tougher patties, were reached after one 10-min cycle in the case of single-cycle treatments or two 5-min cycles in the case of multiple-cycle treatments. High-pressure treatments had no significant effect on Warner-Bratzler shear force.

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Heat Resistance of Escherichia coli O157:H7 in a Nutrient Medium and in Ground Beef Patties as Influenced by Storage and Holding Temperatures

Journal of Food Protection ◽

10.4315/0362-028x-59.3.230 ◽

1996 ◽

Vol 59 (3) ◽

pp. 230-237 ◽

Cited By ~ 70

Author(s):

TIMOTHY C. JACKSON ◽

MARGARET D. HARDIN ◽

GARY R. ACUFF

Keyword(s):

Escherichia Coli ◽

Stationary Phase ◽

Heat Resistance ◽

Elevated Temperatures ◽

Potential Temperature ◽

Ground Beef ◽

Escherichia Coli O157 ◽

Commercial Preparation ◽

E Coli ◽

Beef Patties

Stationary-phase cultures of Escherichia coli O157:H7 were inoculated into tryptic soy broth, sealed in vials, and stored at −18°C for 1, 8, and 15 days, or 3 or 15°C for 3, 6, and 9 h. Thermal resistance was determined at 55°C. Each storage treatment was repeated with additional holding at 23 or 30°C for 1, 2, 3, or 4 h prior to heating to simulate potential temperature abuse during handling. Cultures under treatments enabling the growth of E. coli O157:H7 were generally more heat sensitive than those held at temperatures which restricted growth or enabled growth to stationary phase. Cultures stored frozen (−18°C) without holding at elevated temperatures had greater heat resistance than those stored under refrigeration (3°C) or at 15°C. Subsequent holding of frozen cultures at 23 or 30°C resulted in a decrease in heat resistance. To determine whether these responses would be observed under typical commercial preparation procedures, ground beef patties were inoculated with E. coli O157:H7 and stored at 3 or 15°C for 9 h or at −18°C for 8 d and then held at 21 or 30°C for 0 or 4 h. Patties were grilled to an internal temperature of 54.4°C (130°F), 62.8°C (145°F), or 68.3°C (155°F). Cultures were most resistant in frozen patties, while cultures in patties stored at 15°C were the most heat sensitive. Holding patties at 21 or 30°C prior to grilling resulted in increased sensitivity. Storage and holding temperatures similar to those encountered in food service may influence the ability of E. coli O157:H7 to survive heat treatments.

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Survival of Escherichia coli O157:H7 after Freezing and Thawing in Ground Beef Patties

Journal of Food Protection ◽

10.4315/0362-028x-61.9.1181 ◽

1998 ◽

Vol 61 (9) ◽

pp. 1181-1183 ◽

Cited By ~ 29

Author(s):

JAY R. SAGE ◽

STEVEN C. INGRAM

Keyword(s):

Escherichia Coli ◽

Microwave Heating ◽

Ground Beef ◽

Escherichia Coli O157 ◽

Strain Atcc ◽

E Coli ◽

Population Decrease ◽

Beef Patties ◽

Recovered Strain ◽

Agar Method

Survival of Escherichia coli O157:H7 strains QA 326, and ATCC 43889,43894, and 43895 after freezing (−20°C, 24 h) and thawing (4°C for 12 h, 23°C for 3 h, or microwave heating of 700 W for 120 s) in ground beef patties was determined by reference most probable number (MPN), hydrophobic grid membrane filter SD-39 agar, and sorbitol MacConkey agar (SMA) spread-plating methods. Populations decreased from 0.62 to 2.52 log10 CFU/g, with the extent varying significantly by strain. Strain QA 326 populations almost always decreased the most, up to 1.87 log10 CFU/g more than the least sensitive strain. Microwave heating was the most lethal thawing treatment for strain QA 326, and 4°C thawing was the most lethal treatment for strain ATCC 43894. Thawing treatments varied in relative lethality for the other two strains. For strain QA 326 (4°C and microwave thaw treatments) and strain ATCC 43889 (4 and 23°C thawing), the enumeration method significantly affected a population decrease. The SD-39 agar method best recovered strain QA 326 while the SD-39 agar method and the reference MPN method best recovered strain ATCC 43889 after 4 and 23°C thawing, respectively. The greatest difference in population decrease measured by any two methods was 0.58 log10 CFU/g. Results showed (i) a wide range in freeze-thaw sensitivity among E. coli O157:H7 strains, (ii) no thawing method had consistently and significantly greater lethality, and (iii) the reference MPN, SD-39 agar, and SMA methods differed little in ability to enumerate E. coli O157:H7.

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Incidence of Enterohemorrhagic Escherichia coli, Escherichia coli O157, Salmonella, and Listeria monocytogenes in Retail Fresh Ground Beef, Sprouts, and Mushrooms

Journal of Food Protection ◽

10.4315/0362-028x-69.2.441 ◽

2006 ◽

Vol 69 (2) ◽

pp. 441-443 ◽

Cited By ~ 76

Author(s):

M. SAMADPOUR ◽

M. W. BARBOUR ◽

T. NGUYEN ◽

T.-M. CAO ◽

F. BUCK ◽

...

Keyword(s):

Escherichia Coli ◽

Listeria Monocytogenes ◽

Ground Beef ◽

Food Samples ◽

Enterohemorrhagic Escherichia Coli ◽

Escherichia Coli O157 ◽

E Coli ◽

Pcr Assays ◽

Retail Food

The objective of this study was to determine the prevalence of enterohemorrhagic Escherichia coli (EHEC), E. coli O157, Salmonella, and Listeria monocytogenes in retail food samples from Seattle, Wash. A total of 2,050 samples of ground beef (1,750 samples), mushrooms (100 samples), and sprouts (200 samples) were collected over a 12-month period and analyzed for the presence of these pathogens. PCR assays, followed by culture confirmation were used to determine the presence or absence of each organism. Of the 1,750 ground beef samples analyzed, 61 (3.5%) were positive for EHEC, and 20 (1.1%) of these were positive for E. coli O157. Salmonella was present in 67 (3.8%) of the 1,750 ground beef samples. Of 512 ground beef samples analyzed, 18 (3.5%) were positive for L. monocytogenes. EHEC was found in 12 (6.0%) of the 200 sprout samples, and 3 (1.5%) of these yielded E. coli O157. Of the 200 total sprout samples, 14 (7.0%) were positive for Salmonella and none were positive for L. monocytogenes. Among the 100 mushroom samples, 4 (4.0%) were positive for EHEC but none of these 4 samples were positive for E. coli O157. Salmonella was detected in 5 (5.0%) of the mushroom samples, and L. monocytogenes was found in 1 (1.0%) of the samples.

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Enumeration of Escherichia coli O157:H7 in Outbreak-Associated Beef Patties

Journal of Food Protection ◽

10.4315/0362-028x.jfp-15-521 ◽

2016 ◽

Vol 79 (7) ◽

pp. 1266-1268 ◽

Cited By ~ 9

Author(s):

ALEXANDER GILL ◽

GEORGE HUSZCZYNSKI

Keyword(s):

Escherichia Coli ◽

Ground Beef ◽

Most Probable Number ◽

Escherichia Coli O157 ◽

Cross Contamination ◽

Probable Number ◽

E Coli ◽

Beef Patties ◽

Selective Agar ◽

Agar Media

ABSTRACT An outbreak of five cases of Escherichia coli O157 infection that occurred in Canada in 2012 was linked to frozen beef patties seasoned with garlic and peppercorn. Unopened retail packs of beef patties from the implicated production lot were recovered and analyzed to enumerate E. coli O157, other E. coli strains, and total coliforms. E. coli O157 was not recovered by direct enumeration on selective agar media. E. coli O157 in the samples was estimated at 3.1 most probable number per 140 g of beef patty, other E. coli was 11 CFU/g, and coliforms were 120 CFU/g. These results indicate that the presence of E. coli O157 in ground beef at levels below 0.1 CFU/g may cause outbreaks. However, the roles of temperature abuse, undercooking, and cross-contamination in amplifying the risk are unknown.

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Effects of Vacuum or Modified Atmosphere Packaging in Combination with Irradiation for Control of Escherichia coli O157:H7 in Ground Beef Patties

Journal of Food Protection ◽

10.4315/0362-028x.jfp-11-289 ◽

2011 ◽

Vol 74 (12) ◽

pp. 2018-2023 ◽

Cited By ~ 4

Author(s):

LI L. KUDRA ◽

JOSEPH G. SEBRANEK ◽

JAMES S. DICKSON ◽

AUBREY F. MENDONCA ◽

ELAINE M. LARSON ◽

...

Keyword(s):

Escherichia Coli ◽

Modified Atmosphere Packaging ◽

Ground Beef ◽

Vacuum Packaging ◽

Modified Atmosphere ◽

Escherichia Coli O157 ◽

Refrigerated Storage ◽

High Co2 ◽

E Coli ◽

Beef Patties

The efficacy of controlling Escherichia coli O157:H7 in ground beef patties by combining irradiation with vacuum packaging or modified atmosphere packaging (MAP) was investigated. Fresh ground beef patties were inoculated with a five-strain cocktail of E. coli O157:H7 at 5 log CFU/g. Single patties, packaged with vacuum or high-CO2 MAP (99.6% CO2 plus 0.4% CO), were irradiated at 0 (control), 0.5, 1.0, or 1.5 kGy. The D10-value for this pathogen was 0.47 ± 0.02 kGy in vacuum and 0.50 ± 0.02 kGy in MAP packaging. Irradiation with 1.5 kGy reduced E. coli O157:H7 by 3.0 to 3.3 log, while 0.5 and 1.0 kGy achieved reductions of 0.7 to 1.0, and 2.0 to 2.2 log, respectively. After irradiation, the numbers of survivors of this pathogen on beef patties in refrigerated storage (4°C) did not change significantly for 6 weeks. Temperature abuse (at 25°C) resulted in growth in vacuum-packaged patties treated with 0.5 and 1.5 kGy, but no growth in MAP packages. This study demonstrated that combining irradiation with MAP was similar in effectiveness to irradiation with vacuum packaging for control of E. coli O157:H7 in ground beef patties during refrigerated storage. However, high-CO2 MAP appeared to be more effective after temperature abuse.

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Effectiveness of Two Cooking Systems in Destroying Escherichia coli O157:H7 and Listeria monocytogenes in Ground Beef Patties

Journal of Food Protection ◽

10.4315/0362-028x-63.7.894 ◽

2000 ◽

Vol 63 (7) ◽

pp. 894-899 ◽

Cited By ~ 16

Author(s):

ELAINE M. D'SA ◽

MARK A. HARRISON ◽

SCOTT E. WILLIAMS ◽

MARC H. BROCCOLI

Keyword(s):

Escherichia Coli ◽

Listeria Monocytogenes ◽

Ground Beef ◽

Escherichia Coli O157 ◽

Target Temperature ◽

Internal Temperature ◽

E Coli ◽

Beef Patties ◽

Textural Quality ◽

Rapid Temperature

A rapid, high-temperature double-sided grilling–broiling (DGB) system was compared to a single-sided broiling (SSB) system for cooking of foodservice ground beef patties to reduce microbial numbers and maintain textural quality. Patties (110g) containing either Escherichia coli O157:H7 or Listeria monocytogenes (106–7 CFU/g) were cooked to target internal temperatures of 60 or 68°C on each cooking system and immediately removed from the grills without the additional holding time at 60 or 68°C that is recommended for foodservice cooking of ground beef patties. Actual final internal temperature attained, position on the grill, degree of doneness, cooking time, after-cook weight, texture characteristics, and bacterial counts of the patties were monitored. The DGB reduced E. coli O157:H7 and L. monocytogenes populations in ground beef patties by 5.7 log10 and 5.4 log10 CFU/g, respectively, when cooked to a target temperature of 60°C (actual final internal temperature of 71.2°C) and by 6.1 log10 and 5.6 log10 CFU/g, respectively, when cooked to a target temperature of 68°C (actual final internal temperature of 75.8°C). The SSB reduced E. coli O157:H7 and L. monocytogenes populations by 1.3 log10 and 1.8 log10 CFU/g, respectively, when cooked to a target temperature of 60°C (actual final internal temperature of 62.7°C) and by 2.9 log10 and 3.6 log10 CFU/g, respectively, when cooked to a target temperature of 68°C (actual final internal temperature of 69.3°C). The DGB system effected a higher, more rapid temperature increase in patties cooked to either target temperature compared to the SSB system. This higher temperature was more effective in destroying pathogens in beef patties. Texture analyses determined that patties cooked on the DGB system had significantly higher values for springiness, adhesiveness, and product height as compared to the SSB system, and patties cooked on either system had significantly higher hardness, gumminess, chewiness, and product height values at the target temperature of 68°C as compared to 60°C.

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