Thermal Destruction of Escherichia coli O157:H7 in Sous-Vide Cooked Ground Beef as Affected by Tea Leaf and Apple Skin Powders†

2009 ◽  
Vol 72 (4) ◽  
pp. 860-865 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
M. L. BARI ◽  
Y. INATSU ◽  
S. KAWAMOTO ◽  
MENDEL FRIEDMAN
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Inactivation Kinetics ◽  
Skin Extract ◽  
Escherichia Coli O157 ◽  
Circulating Water ◽  
Sous Vide ◽  
D Values ◽  
A Minor ◽  
D Value

We investigated the heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of white and green tea powders and an apple skin extract. Inoculated meat was cooked using the sous-vide technique, i.e., the meat was packaged in sterile bags and completely immersed in a circulating water bath at low temperature for a period of time. The bags were cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5°C, and then held from 240 min at 55°C to 10 min at 62.5°C. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol-MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time, in minutes, required for the bacteria to decrease by 90%) in the control beef ranged from 67.79 min at 55°C to 2.01 min at 62.5°C. D-values determined by a logistic model ranged from 36.22 (D1, the D-value of a major population of surviving cells) and 112.79 (D2, the D-value of a minor subpopulation) at 55°C to 1.39 (D1) and 3.00 (D2) at 62.5°C. A significant increase (P < 0.05) in the sensitivity of the bacteria to heat was observed with the addition of 3% added antimicrobials. D-value reductions of 62 to 74% were observed with apple powder and 18 to 58% with tea powders. Thermal death times from this study will assist the retail food industry to design cooking regimes that ensure the safety of beef contaminated with E. coli O157:H7.

Carvacrol and Cinnamaldehyde Facilitate Thermal Destruction of Escherichia coli O157:H7 in Raw Ground Beef†

2008 ◽  
Vol 71 (8) ◽  
pp. 1604-1611 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
MENDEL FRIEDMAN
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
Internal Temperature ◽  
Circulating Water ◽  
Critical Control Points ◽  
Thermal Death ◽  
D Values ◽  
D Value

The heat resistance of a four-strain mixture of Escherichia coli O157:H7 in raw ground beef in both the absence and presence of the antimicrobials carvacrol and cinnamaldehyde was tested at temperatures ranging from 55 to 62.5°C. Inoculated meat packaged in bags was completely immersed in a circulating water bath, cooked for 1 h to an internal temperature of 55, 58, 60, or 62.5°C, and then held for predetermined lengths of time ranging from 210 min at 55°C to 5 min at 62.5°C. The surviving bacteria were enumerated by spiral plating onto tryptic soy agar overlaid with sorbitol MacConkey agar. Inactivation kinetics of the pathogens deviated from first-order kinetics. D-values (time for the bacteria to decrease by 90%) in the control beef ranged from 63.90 min at 55°C to 1.79 min at 62.5°C. D-values determined by a logistic model ranged from 43.18 min (D1, the D-value of a major population of surviving cells) and 89.84 min (D2, the D-value of a minor subpopulation) at 55°C to 1.77 (D1) and 0.78 min (D2) at 62.5°C. The thermal death times suggested that to achieve a 4-D reduction, contaminated processed ground beef should be heated to an internal temperature of 60°C for at least 30.32 min. Significantly increased sensitivity to heat (P < 0.05) was observed with the addition and/or increasing levels of carvacrol or cinnamaldehyde from 0.5 to 1.0%. The observed thermal death times may facilitate the design of acceptance limits at critical control points for ground beef at lower times and temperatures of heating.

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.

Lethality of Heat to Escherichia coli 0157:H7: D-Value and Z-Value Determinations in Ground Beef

1991 ◽  
Vol 54 (10) ◽  
pp. 762-766 ◽  
Author(s):  
J. ERIC LINE ◽  
ALFRED R. FAIN ◽  
ALICE B. MORAN ◽  
L. MICHELE MARTIN ◽  
RICHARD V. LECHOWICH ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Plate Count ◽  
Ground Meat ◽  
Plate Count Agar ◽  
Death Time ◽  
Lean Beef ◽  
Z Value ◽  
D Values ◽  
D Value

D-values and z-values were determined for lean (2.0% fat) and fatty (30.5% fat) ground beef inoculated with approximately 107 Escherichia coli 0157:H7 cells per g. Inoculated ground meat was sealed in glass thermal death time tubes which were completely immersed in a circulating water bath and held at prescribed temperatures for predetermined lengths of time. Survival was determined by enumeration on plate count agar (PCA) containing 1% sodium pyruvate and by the 2-h indole test of Lee and McClain (7). D-values for fatty ground beef exceeded those for lean ground beef at the temperatures tested. D-values for lean and fatty ground beef at 125°F were 78.2 and 115.5 min, respectively, as enumerated on PCA plus pyruvate. D-values at 135°F were 4.1 and 5.3 min for lean and fatty beef. At 145°F D-values were determined to be 0.3 and 0.5 min. D-values calculated from 2-h indole test data for lean and fatty ground beef at 125°F were 80.1 and 121.0 min, respectively. D-values at 135°F were 4.0 and 7.4 min for lean and fatty beef and at 145°F a D-value of 0.2 min was calculated for lean beef only, due to insufficient survival of E. coli 0157:H7 in fatty beef at this temperature. The z-values determined for lean beef and fatty beef using PCA were 8.3 and 8.4°F respectively. The z-value for lean beef using the 2-h indole data was 7.8°F. No z-value for fatty beef using 2-h indole data could be determined.

A New Kinetic Model for Thermal Inactivation of Microorganisms: Development and Validation Using Escherichia coli O157:H7 as a Test Organism†

2001 ◽  
Vol 64 (12) ◽  
pp. 2078-2082 ◽  
Author(s):  
LIHAN HUANG ◽  
VIJAY K. JUNEJA
Keyword(s):  
Escherichia Coli ◽  
Kinetic Model ◽  
Thermal Inactivation ◽  
Test Organism ◽  
Nonlinear Behavior ◽  
Ground Beef ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
First Order ◽  
Test Microorganism

A new kinetic model has been proposed to simulate the nonlinear behavior of survivor curves frequently observed in thermal inactivation of microorganisms. This model incorporates a time component into the first-order inactivation kinetics and is capable of describing the linear, convex, and concave survivor curves. The model was validated using Escherichia coli O157:H7 as a test microorganism. Ground beef (93% lean) samples inoculated to 107 to 108 CFU/g of meat were subjected to immersion heating at 55, 57.5, 60, 62.5, and 65°C, respectively, in a water bath. All the survivor curves in this study showed upward concavity. Linear and nonlinear regressions were used to fit the survivor curves to the linear first-order inactivation kinetics and the proposed model. Analyses showed that the new kinetic model provides a much better estimate of the thermal inactivation behavior of E. coli O157:H7 in ground beef.

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.

Changes in Heat Resistance of Escherichia coli O157:H7 Following Heat Shock

1997 ◽  
Vol 60 (9) ◽  
pp. 1128-1131 ◽  
Author(s):  
NICOLE C. WILLIAMS ◽  
STEVEN C. INGHAM
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Heat Resistance ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
Protective Effects ◽  
Cell Recovery ◽  
Short Term ◽  
E Coli ◽  
D Values

This study examined the effects of a heat shock at 45°C for 30 min on the subsequent heat resistance of Escherichia coli O157:H7 ATCC 43894 in Trypticase soy broth (TSB) and ground beef slurry (GBS). Cultures were grown to stationary phase, stored for 24 h at 4 to 6°C, and then heat shocked to simulate consumer mishandling of meat during the summer. Control or heat-shocked ATCC 43894 cells were then transferred to prewarmed TSB (54, 58, and 62°C) or GBS (58°C) and refrigerated TSB and GBS that were subsequently heated to and held at 58°C (TSB and GBS) and 62°C (TSB only). Heat shock increased D values by 37, 68, and 50% in 54, 58, and 62°C prewarmed TSB, respectively, but had no significant effect on the D value in 58°C GBS. Immediate plating of heated samples yielded greater cell recovery than if samples were held on ice prior to plating. Heat shock did not lead to significant increases in D values when cells were transferred to 4°C TSB and GBS that were heated to the test temperature. This study showed that for E. coli O157:H7 ATCC 43894 the heat-shock effect was lost upon subsequent chilling and rewarming and overshadowed by the protective effects of ground beef constituents. The results do not support the hypothesis that short-term temperature abuse will significantly increase the heat resistance of E. coli O157:H7 in ground beef.

Lethality of Heat to Listeria monocytogenes Scott A: D-Value and Z-Value Determinations in Ground Beef and Turkey

1991 ◽  
Vol 54 (10) ◽  
pp. 756-761 ◽  
Author(s):  
ALFRED R. FAIN ◽  
J. ERIC LINE ◽  
ALICE B. MORAN ◽  
L. MICHELE MARTIN ◽  
RICHARD V. LECHOWICH ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Ground Beef ◽  
Ground Meat ◽  
Circulating Water ◽  
Death Time ◽  
Lean Beef ◽  
Z Value ◽  
D Values ◽  
Thermal Death Time ◽  
D Value

D-Values and z-values for Listeria monocytogenes strain Scott A were determined in lean (2.0% fat) and fatty (30.5%) ground beef inoculated with approximately 107cells/g. Inoculated ground meat was sealed in glass thermal death time tubes which were completely immersed in a circulating water bath and held at prescribed temperatures for predetermined lengths of time. Survival was determined by enumeration on Columbia CNA agar base containing 1% sodium pyruvate with a CNA + 4% horse blood overlay (CBNA) and on Listeria Plating Medium (LPM). D-values for L. monocytogenes in lean and fatty ground beef at 125° were 81.3 and 71.1 min, respectively, as enumerated on CBNA plus pyruvate. D-values at 135°F were 2.6 and 5.8 min in lean and fatty beef. At 145°F, D-values were determined to be 0.6 and 1.2 min. D-values calculated from LPM recovery data from fatty ground beef at 125°F were 56.1 and 34.5 min, respectively. D-values at 135°F were 2.4 and 4.6 min in lean and fatty beef. At 145°F a D-value of 0.5 min was calculated in lean beef and a D-value of 1.1 min was determined in fatty beef. The z-values determined in lean beef and fatty beef using CBNA recovery data were 9.3 and 11.4°F, respectively. The z-value in lean beef using LPM recovery data was 9.8°F. The z-value in fatty beef using LPM recovery data was 13.2°F. A D-value for ground turkey meat at 160°F could not be determined under the conditions of this study. Problems encountered are discussed.

Thermal Inactivation of Escherichia coli O157:H7 in Ground Beef Supplemented with Sodium Lactate†

2003 ◽  
Vol 66 (4) ◽  
pp. 664-667 ◽  
Author(s):  
LIHAN HUANG ◽  
VIJAY K. JUNEJA
Keyword(s):  
Escherichia Coli ◽  
Thermal Resistance ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Ground Beef ◽  
Antimicrobial Effect ◽  
Sodium Lactate ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
D Values

A study was conducted to investigate the antimicrobial effect of sodium lactate (NaL) (0, 1.5, 3.0, and 4.5%) on the survival of Escherichia coli O157:H7 in 93% lean ground beef. Samples inoculated with a mixture of four strains of E. coli O157:H7 (107 to 108 CFU/g) were subjected to immersion heating in a water bath stabilized at 55, 57.5, 60, 62.5, or 65°C. Results of statistical analysis indicated that the heating temperature was the only factor affecting the decimal reduction times (D-values) of E. coli O157:H7 in 93% lean ground beef. The change in temperature required to change the D-value (the z-value) was determined as 7.6°C. The thermal resistance of this organism was neither affected by the addition of NaL nor by the interactions between NaL and temperature. Adding NaL to ground beef to reduce the thermal resistance of E. coli O157: H7 is therefore not recommended.

Thermal Process Validation for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in Ground Turkey and Beef Products

2004 ◽  
Vol 67 (7) ◽  
pp. 1394-1402 ◽  
Author(s):  
R. Y. MURPHY ◽  
E. M. MARTIN ◽  
L. K. DUNCAN ◽  
B. L. BEARD ◽  
J. A. MARCY
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Thermal Inactivation ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
Process Validation ◽  
E Coli ◽  
Beef Products ◽  
Air Impingement ◽  
D Values

At 55 to 70°C, thermal inactivation D-values for Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes were 19.05 to 0.038, 43.10 to 0.096, and 33.11 to 0.12 min, respectively, in ground turkey and 21.55 to 0.055, 37.04 to 0.066, and 36.90 to 0.063 min, respectively, in ground beef. The z-values were 5.73, 5.54, and 6.13°C, respectively, in ground turkey and 5.43, 5.74, and 6.01°C, respectively, in ground beef. In both ground turkey and beef, significant (P < 0.05) differences were found in the D-values between E. coli O157:H7 and Salmonella or between E. coli O157:H7 and L. monocytogenes. At 65 to 70°C, D-values for E. coli O157:H7, Salmonella, and L. monocytogenes were also significantly (P < 0.05) different between turkey and beef. The obtained D- and z-values were used in predicting process lethality of the pathogens in ground turkey and beef patties cooked in an air impingement oven and confirmed by inoculation studies for a 7-log (CFU/g) reduction of E. coli O157:H7, Salmonella, and L. monocytogenes.

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