Predictive Thermal Inactivation Model for Listeria monocytogenes with Temperature, pH, NaCl, and Sodium Pyrophosphate as Controlling Factors†

1999 ◽  
Vol 62 (9) ◽  
pp. 986-993 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
BRIAN S. EBLEN
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Predictive Model ◽  
Heating Temperature ◽  
Sodium Pyrophosphate ◽  
Effect Of Temperature ◽  
Plate Count ◽  
Heat Inactivation ◽  
Heat Sensitivity ◽  
D Values

The effects and interactions of heating temperature (55 to 65°C), pH (4 to 8), salt (NaCl; 0 to 6%, wt/vol), and sodium pyrophosphate (SPP; 0 to 0.3%, wt/vol) on the heat inactivation of a four-strain mixture of Listeria monocytogenes in beef gravy were examined. A factorial experimental design comparing 48 combinations of heating temperature, salt concentration, pH value, and SPP content was used. Heating was carried out using a submerged-coil heating apparatus. The recovery medium was plate count agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. Decimal reduction times (D-values) were calculated by fitting a survival model to the data with a curve-fitting program. The D-values were analyzed by second-order response surface regression for temperature, pH, NaCl, and SPP levels. Whereas increasing the NaCl concentration protected L. monocytogenes against the lethal effect of heat, high SPP concentrations increased heat sensitivity. Also, low pH values increased heat sensitivity of L. monocytogenes. The four variables interacted to affect the inactivation of the pathogen. Thermal resistance of L. monocytogenes can be lowered by combining these intrinsic factors. A predictive model that described the combined effect of temperature, pH, NaCl, and SPP levels on thermal resistance of L. monocytogenes was developed. The model can predict D-values for any combination of temperature, pH, NaCl, and SPP that are within the range of those tested. Using this predictive model, food processors should be able to design adequate thermal regimes to eliminate L. monocytogenes in thermally processed foods.

A Predictive Model To Determine the Effects of Temperature, Sodium Pyrophosphate, and Sodium Chloride on Thermal Inactivation of Starved Listeria monocytogenes in Pork Slurry

2003 ◽  
Vol 66 (7) ◽  
pp. 1216-1221 ◽  
Author(s):  
M. A. LIHONO ◽  
A. F. MENDONCA ◽  
J. S. DICKSON ◽  
P. M. DIXON
Keyword(s):  
Listeria Monocytogenes ◽  
Predictive Model ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Sodium Pyrophosphate ◽  
Effect Of Temperature ◽  
Destructive Effect ◽  
Processed Meats ◽  
Natural Logarithm ◽  
D Values

The effects and interactions of 27 combinations of heating temperature (57.5 to 62.5°C), sodium pyrophosphate (SPP) level (0 to 0.5%, wt/vol), and salt (NaCl) level (0 to 6%, wt/vol) on the thermal inactivation of starved Listeria monocytogenes ATCC 19116 in pork slurry were investigated. A split-split plot experimental design was used to compare all 27 combinations. L. monocytogenes survivors were enumerated on tryptic soy agar supplemented with 0.6% yeast extract. The natural logarithm (loge) of the means of decimal reduction times (D-values) were modeled as a function of temperature, SPP level, and NaCl level. Increasing concentrations of SPP or NaCl protected starved L. monocytogenes from the destructive effect of heat. For example, D-values for the pathogen at 57.5°C in pork slurry with 0, 3, and 6% NaCl were 2.79, 7.75, and 14.59 min, respectively. All three variables interacted to affect the thermal inactivation of L. monocytogenes. A mathematical model describing the combined effect of temperature, SPP level, and NaCl level on the thermal inactivation of starved L. monocytogenes was developed. There was strong correlation (R2 = 0.97) between loge D-values predicted by the model and those observed experimentally. The model can predict D-values for any combination of variables that falls within the range of those tested. This predictive model can be used to assist food processors in designing thermal processes that include an adequate margin of safety for the control of L. monocytogenes in processed meats.

Predictive Model for the Combined Effect of Temperature, Sodium Lactate, and Sodium Diacetate on the Heat Resistance of Listeria monocytogenes in Beef†

2003 ◽  
Vol 66 (5) ◽  
pp. 804-811 ◽  
Author(s):  
VIJAY K. JUNEJA
Keyword(s):  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Predictive Model ◽  
Heating Temperature ◽  
Practical Importance ◽  
Sodium Lactate ◽  
Combined Effect ◽  
Effect Of Temperature ◽  
Sodium Diacetate ◽  
D Values

The effects of heating temperature (60 to 73.9°C), sodium lactate (NaL; 0.0 to 4.8% [wt/wt]), and/or sodium diacetate (SDA; 0.0 to 0.25% [wt/wt]) and of the interactions of these factors on the heat resistance of a five-strain mixture of Listeria monocytogenes in 75% lean ground beef were examined. Thermal death times for L. monocytogenes in filtered stomacher bags in a circulating water bath were determined. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. Decimal reduction times (D-values) were calculated by fitting a survival model to the data with a curve-fitting program. The D-values were analyzed by second-order response surface regression for temperature, NaL level, and SDA level. The D-values observed for beef with no NaL or SDA at 60, 65, 71.1, and 73.9°C were 4.67, 0.72, 0.17, and 0.04 min, respectively. The addition of 4.8% NaL to beef increased heat resistance at all temperatures, with D-values ranging from 14.3 min at 60°C to 0.13 min at 73.9°C. Sodium diacetate interacted with NaL, thereby reducing the protective effect of NaL and rendering L. monocytogenes in beef less resistant to heat. A mathematical model describing the combined effect of temperature, NaL level, and SDA level on the thermal inactivation of L. monocytogenes was developed. This model can predict D-values for any combination of temperature, NaL level, and SDA level that is within the range of those tested. This predictive model will have substantial practical importance to processors of cooked meat, allowing them to vary their thermal treatments of ready-to-eat meat products in a safe manner.

Modeling the Effects of Temperature, Sodium Chloride, and Green Tea and Their Interactions on the Thermal Inactivation of Listeria monocytogenes in Turkey†

2014 ◽  
Vol 77 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
JIMENA GARCIA-DÁVILA ◽  
JULIO CESAR LOPEZ-ROMERO ◽  
ETNA AIDA PENA-RAMOS ◽  
JUAN PEDRO CAMOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Protective Effect ◽  
Heat Resistance ◽  
Green Tea ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Lethal Effect ◽  
Interactive Effects ◽  
D Values

The interactive effects of heating temperature (55 to 65°C), sodium chloride (NaCl; 0 to 2%), and green tea 60% polyphenol extract (GTPE; 0 to 3%) on the heat resistance of a five-strain mixture of Listeria monocytogenes in ground turkey were determined. Thermal death times were quantified in bags that were submerged in a circulating water bath set at 55, 57, 60, 63, and 65°C. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, NaCl, and GTPE. The data indicated that all three factors interacted to affect the inactivation of the pathogen. The D-values for turkey with no NaCl or GTPE at 55, 57, 60, 63, and 65°C were 36.3, 20.8, 13.2, 4.1, and 2.9 min, respectively. Although NaCl exhibited a concentration-dependent protective effect against heat lethality on L. monocytogenes in turkey, addition of GTPE rendered the pathogen more sensitive to the lethal effect of heat. GTPE levels up to 1.5% interacted with NaCl and reduced the protective effect of NaCl on heat resistance of the pathogen. Food processors can use the predictive model to design an appropriate heat treatment that would inactivate L. monocytogenes in cooked turkey products without adversely affecting the quality of the product.

Thermal Reduction of Bacillus spp. in Naturally Contaminated Mesquite Flour with Two Different Water Activities

2020 ◽  
Author(s):  
Xuetong Fan ◽  
Jessica Baik ◽  
Joshua Gurtler
Keyword(s):  
Thermal Resistance ◽  
Bacillus Cereus ◽  
Sugar Content ◽  
Thermal Reduction ◽  
Treatment Temperature ◽  
Heat Sensitivity ◽  
Mesophilic Bacteria ◽  
High Sugar Content ◽  
Bacillus Spp ◽  
D Values

Mesquite flour with endogenous high sugar content is often contaminated with Bacillus cereus.  The purpose of the present study was to evaluate the thermal resistance of Bacillus spp. in naturally contaminated mesquite flour. Flours with and without adjusted water activity (aw) were treated at various temperatures (100-140°C) and times (up to 2 h). Total mesophilic bacteria and Bacillus spp. were enumerated using tryptic soy agar and Brilliance Bacillus Cereus Agar media, respectively. Results revealed that naturally contaminated Bacillus spp. and other mesophilic bacteria in mesquite flour (aw=0.34) were highly resistant to heat. To reduce the initial populations (4.75 log CFU/g) of Bacillus spp. to non-detectable levels (<1.18 log CFU/g), thermal treatments of 120°C for 2 h were required. D100°C-values for total mesophilic bacteria were 5.6 fold higher than those of Bacillus spp. With increasing treatment temperature, the D-value between total mesophilic bacteria and B. cereus became smaller. When the aw of flour was adjusted from 0.34 to 0.71, the D-values for Bacillus decreased significantly.  Treatment at 100°C for 1 h reduced Bacillus spp. populations to nondetectable levels.  Our results demonstrate that naturally present Bacillus spp. in flour are highly resistant to heat, while increasing the aw increased their heat sensitivity.  The high thermal resistance of microbes in mesquite flour warrants further investigations.

Thermal Resistance of Listeria monocytogenes in Milk

1985 ◽  
Vol 48 (9) ◽  
pp. 743-745 ◽  
Author(s):  
J. G. BRADSHAW ◽  
J. T. PEELER ◽  
J. J. CORWIN ◽  
J. M. HUNT ◽  
J. T. TIERNEY ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Whole Milk ◽  
D Values ◽  
D Value

The thermal resistance of Listeria monocytogenes associated with a milkborne outbreak of listeriosis was determined in buffer and whole milk. Thermal resistance was stable over a 2-year period and could not be altered by selecting heat-stressed survivors. The rate of inactivation was linear and did not differ significantly between pH 5.5 and 9.0. When portions of whole milk containing 1 × 105 cells of L. monocytogenes/ml were heated at seven temperatures from 52.2 to 74.4°C, the D-values ranged from 1683.7 to 0.7 s, respectively. The zD-value was 6.3°C. The D-value at 71.7°C was 0.9 s. L. monocytogenes would not survive the pasteurization process.

Thermal Inactivation, Growth, and Survival Studies of Listeria monocytogenes Strains Belonging to Three Distinct Genotypic Lineages

2003 ◽  
Vol 66 (9) ◽  
pp. 1611-1617 ◽  
Author(s):  
ANTONIO J. DE JESÚS ◽  
RICHARD C. WHITING
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Inactivation ◽  
Brain Heart Infusion ◽  
Growth Conditions ◽  
Heat Inactivation ◽  
Survival Times ◽  
Growth And Survival ◽  
Coefficients Of Variation ◽  
Survival Studies ◽  
D Values

Twenty-one Listeria monocytogenes strains belonging to three different genotypic lineages were evaluated for differences between lineages and between individual strains with respect to thermal inactivation, growth, and survival. Three sets of heat inactivation conditions (60°C, pH 6.0, and 0.5 M lactate; 55°C, pH 6.0, and 0.5 M lactate; and 50°C, pH 4.0, and 0.5 M lactate) were used on strains grown in modified brain heart infusion (BHI) broth with and without glucose. Two sets of growth conditions (35°C, pH 6.5, and 0.1 M lactate and 5°C, pH 6.5, and 0.1 M lactate) were used with modified BHI broths to determine lag phases and exponential growth rates. Two sets of conditions (28°C, pH 4.0, and 1 M lactate and 28°C, pH 4.5, and 0.5 M lactate) were used with modified BHI broth to determine survival times (D-values). Thermal inactivation D-values were consistently lowest for lineage III, but differences were not significant for any set of conditions tested. Some significant differences were observed between lineages with respect to some of the growth and survival conditions tested. Extensive strain-to-strain variation was observed for all parameters tested. Average coefficients of variation for the thermal inactivation, growth, and survival studies were 0.31, 0.18, and 0.26, respectively. Strain-to-strain variations were approximately equal to the uncertainties associated with the analytical procedures. The results obtained indicate a diversity among strains encountered in food processing that must be accounted for in process calculations and risk assessments.

Thermal Resistance of Listeria monocytogenes and Salmonella spp. in Liquid Egg White

1996 ◽  
Vol 59 (11) ◽  
pp. 1182-1186 ◽  
Author(s):  
M. S. PALUMBO ◽  
S. M. BEERS ◽  
S. BHADURI ◽  
S. A. PALUMBO
Keyword(s):  
Hydrogen Peroxide ◽  
Listeria Monocytogenes ◽  
Salmonella Enteritidis ◽  
Egg White ◽  
Heat Sensitivity ◽  
Salmonella Spp ◽  
Single Strain ◽  
Ph Values ◽  
D Values ◽  
Unit Reduction

Survival of a five-strain mixture of Listeria monocytogenes and a six-strain mixture of Salmonella enteritidis, S. typhimurium, and S. senftenberg (not 775W) in liquid egg white was determined by a submerged-vial technique at 51.5°C and 53.2°C with 0.875% added H2O2 and at 55.5°C, 56.6°C, and 57.7°C with no additions. Survival at a range of pH values at 56.6°C also was determined. Surviving bacteria were counted on tryptic soy agar and results expressed as D-values; log-unit reductions in counts in 3.5 min or 6.2 min were calculated from these D-values. Plate pasteurization of commercially broken egg white (pH 8.8) inoculated with a single strain of L. innocua or S. senftenberg also was performed. Heating under currently approved pasteurization conditions, 51.5°C for 3.5 min with hydrogen peroxide, 55.6°C for 6.2 min, or 56.7°C for 3.5 min, resulted in a less than 3-1og unit reduction of viable Salmonella spp. and a less than 0.5-1og unit reduction of L. monocytogenes. At 53.2°C with peroxide, plate pasteurization resulted in a 3.44-1og unit reduction of S. senftenberg in 3.5 min. At 57.7°C with no peroxide, the D-value for Salmonella spp. was 0.78 min when heated in submerged vials, and plate pasteurization reduced viable numbers by 3.64 log units in 3.5 min. Destruction of Listeria under these conditions was still less than 1 log unit. Variation in the pH of the egg white from 7.8 to 9.3 resulted in D-values for Salmonella spp. at 56.6°C of 3.60 min to 1.08 min, respectively. D-values for L. monocytogenes under these conditions ranged from 10.4 min at pH 7.8 to 20.9 min at pH 9.3. The reduced heat sensitivity of Salmonella spp. at lower pH values should be considered in reevaluating pasteurization procedures.

The Effect of Temperature and Low pH on Survival of Shigella flexneri in Broth†,‡

2001 ◽  
Vol 64 (8) ◽  
pp. 1162-1165 ◽  
Author(s):  
LAURA L. ZAIKA
Keyword(s):  
Shigella Flexneri ◽  
Brain Heart Infusion ◽  
Low Ph ◽  
Effect Of Temperature ◽  
Plate Count ◽  
Two Phase ◽  
Bacterial Populations ◽  
General Survival ◽  
Lag Times ◽  
D Values

The survival characteristics of Shigella flexneri strain 5348 were determined in brain heart infusion broth as a function of low pH (2 to 5) and temperature (4 to 37°C). Stationary-phase cells were inoculated into sterile media to give initial populations of 6 to 7 log10 CFU/ml. Bacterial populations were determined periodically by aerobic plate counts. Survivor curves were fitted from plate count data using a two-phase linear model to derive lag times and slopes of the curves, from which D-values and times to a 4-D (99.99%) inactivation (T4D) were calculated. In general, survival increased as temperature decreased and as pH increased. Bacterial populations reached undetectable levels (<1.3 log10 CFU/ml) at 37, 28, 19, 12, and 4°C in media adjusted to pH 4 after 5, 15, 23, 85, and 85 days, respectively, and in media adjusted to pH 3 after 1, 7, 9, 16, and 29 days, respectively. In media adjusted to pH 2, bacterial populations were stable for 2 to 12 h at temperatures of 19°C or lower and reached undetectable levels after 1 to 3 days, while at 28 and 37°C, the bacteria were undetectable after 8 and 2 h, respectively. In media adjusted to pH 5, bacterial levels decreased only 0.5 to 1.5 log10 CFU/ml after 75 days at 4°C and decreased to undetectable levels after 135 days at 12°C, while growth occurred at higher temperatures. These results indicate that S. flexneri is acid resistant and that acidic foods may serve as vehicles for infection.

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