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.

Effect of Prior Growth Conditions on the Thermal Inactivation of 13 Strains of Listeria monocytogenes in Two Heating Menstrua

2005 ◽  
Vol 68 (1) ◽  
pp. 168-172 ◽  
Author(s):  
SHARON G. EDELSON-MAMMEL ◽  
RICHARD C. WHITING ◽  
SAM W. JOSEPH ◽  
ROBERT L. BUCHANAN
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Resistance ◽  
Stationary Phase ◽  
Thermal Tolerance ◽  
Thermal Inactivation ◽  
Brain Heart Infusion ◽  
Acid Resistance ◽  
Growth Conditions ◽  
Ph Values ◽  
Ph Dependent

The thermal tolerance of 13 Listeria monocytogenes strains was tested using a submerged heating coil apparatus. The strains were grown individually for 18 h at 37°C in acidogenic tryptic soy broth (without dextrose) supplemented with 1% glucose and 1% glutamine (TSB+G) or nonacidogenic tryptic soy broth supplemented with 1% glutamine but containing no glucose (dextrose) (TSB−G). The former medium results in cells induced for pH-dependent, stationary-phase acid resistance, whereas the latter medium allows L. monocytogenes to grow to high numbers in the absence of glucose, yielding cells that are not induced for pH-dependent, stationary-phase acid resistance. The average final pH values of the 18-h TSB+G and the TSB−G cultures were 4.7 and 6.7, respectively. The cells grown in the acid resistance–inducing and non–acid resistance–inducing media were then tested in two heating menstrua that consisted of brain heart infusion broth adjusted to pH 3.0 and water activity (aw) of 0.987 or pH 7.0 and aw 0.970. In 14 of the 26 menstruum-strain combinations tested, the acid resistance–induced strains were more heat resistant then the equivalent noninduced cultures. No difference in the pattern of thermal resistance in response to induction of acid resistance was apparent among the different serovars tested. The results suggest that the ability of prior induction of acid resistance to enhance thermal resistance can vary substantially among L. monocytogenes strains.

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 Inactivation of Listeria monocytogenes in Chicken Gravy

1992 ◽  
Vol 55 (7) ◽  
pp. 492-496 ◽  
Author(s):  
I-PING D. HUANG ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH ◽  
M. EILEEN MATTHEWS
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Thermal Inactivation ◽  
Refrigerated Storage ◽  
Department Of Agriculture ◽  
Large Numbers ◽  
Z Value ◽  
D Values ◽  
The U.S

Heat resistance of Listeria monocytogenes strains V7 and Scott A in chicken gravy and changes in heat resistance during refrigerated storage were studied. After chicken gravy was made, it was cooled to 40°C, inoculated with 105 CFU L. monocytogenes per ml of gravy, and then stored at 7°C for 10 d. Gravy was heated at 50, 55, 60, and 65°C immediately after inoculation and after 1, 3, 5, and 10 d of refrigerated storage. The D values for strains Scott A and V7 in gravy heated at 50°C at day 0 were 119 and 195 min and at day 10 they were 115 and 119 min, respectively, whereas at 65°C comparable values at day 0 were 0.48 and 0.19 min and at day 10 they were 0.014 and 0.007 min. Heat resistance (expressed as D values) was greater at day 0 than at the end of refrigerated storage. The z values ranged from 3.41 to 6.10°C and were highest at the early stages of chill storage and then decreased at the later stages. Strain V7 was more heat resistant than Scott A at 50°C. Strain Scott A always had a higher z value than did strain V7 at the same storage interval. A heat treatment greater than the 4-D process recommended by the U.S. Department of Agriculture was required to inactivate the large numbers of L. monocytogenes that developed in chicken gravy during refrigerated storage.

Determination of the Thermal Inactivation Kinetics of Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7 and non-O157 in Buffer and a Spinach Homogenate

2015 ◽  
Vol 78 (8) ◽  
pp. 1467-1471 ◽  
Author(s):  
EMEFA ANGELICA MONU ◽  
MALCOND VALLADARES ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Enterica ◽  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Mild Heat ◽  
Log Reduction ◽  
D Values ◽  
Heat Processes ◽  
Kinetics Of

Produce has been associated with a rising number of foodborne illness outbreaks. While much produce is consumed raw, some is treated with mild heat, such as blanching or cooking. The objectives of this research were to compare the thermal inactivation kinetics of Listeria monocytogenes, Salmonella enterica, Shiga toxin–producing Escherichia coli (STEC) O157:H7, and non-O157 STEC in phosphate-buffered saline (PBS; pH 7.2) and a spinach homogenate and to provide an estimate of the safety of mild heat processes for spinach. Five individual strains of S. enterica, L. monocytogenes, STEC O157:H7, and non-O157 STEC were tested in PBS in 2-ml glass vials, and cocktails of the organisms were tested in blended spinach in vacuum-sealed bags. For Listeria and Salmonella at 56 to 60°C, D-values in PBS ranged from 4.42 ± 0.94 to 0.35 ± 0.03 min and 2.11 ± 0.14 to 0.16 ± 0.03 min, respectively. D-values at 54 to 58°C were 5.18 ± 0.21 to 0.53 ± 0.04 min for STEC O157:H7 and 5.01 ± 0.60 to 0.60 ± 0.13 min for non-O157 STEC. In spinach at 56 to 60°C, Listeria D-values were 11.77 ± 2.18 to 1.22 ± 0.12 min and Salmonella D-values were 3.51 ± 0.06 to 0.47 ± 0.06 min. D-values for STEC O157:H7 and non-O157 STEC were 7.21 ± 0.17 to 1.07 ± 0.11 min and 5.57 ± 0.38 to 0.99 ± 0.07 min, respectively, at 56 to 60°C. In spinach, z-values were 4.07 ± 0.16, 4.59 ± 0.26, 4.80 ± 0.92, and 5.22 ± 0.20°C for Listeria, Salmonella, STEC O157:H7, and non-O157 STEC, respectively. Results indicated that a mild thermal treatment of blended spinach at 70°C for less than 1 min would result in a 6-log reduction of all pathogens tested. These findings may assist the food industry in the design of suitable mild thermal processes to ensure food safety.

Evaluation of Microbiological Safety of Shrimp Cooked in a Microwave Oven

1995 ◽  
Vol 58 (7) ◽  
pp. 742-747 ◽  
Author(s):  
SRIKANTH GUNDAVARAPU ◽  
YEN-CON HUNG ◽  
ROBERT E. BRACKETT ◽  
P. MALLIKARJUNAN
Keyword(s):  
Mathematical Model ◽  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Constant Temperature ◽  
Microwave Power ◽  
Thermal Inactivation ◽  
Microwave Oven ◽  
D Values ◽  
Cooking Times ◽  
Temperature Water

The effect of different microwave power levels (240, 400, 560, and 800 W) on the survival of Listeria monocytogenes in inoculated shrimp was investigated. Thermal inactivation rates (D-values) of L. monocytogenes were determined using constant temperature water baths to establish the heat resistance of L. monocytogenes in shrimp. Shrimp were inoculated with approximately 5 × 105 CFU/g of a five-strain mixture of L. monocytogenes. One hundred grams of shrimp were cooked in the microwave oven at different power levels using cooking times predicted by a mathematical model as well as 20% longer times than those obtained from the model. No viable L. monocytogenes were detected in uninoculated shrimp after microwave cooking, but at least one replication of inoculated shrimp tested positive for the presence of Listeria. No viable L. monocytogenes were detected in shrimp cooked at 120% of predicted times.

Synergistic Effects of Butyl Para-Hydroxybenzoate and Mild Heating on Foodborne Pathogenic Bacteria

2020 ◽  
Author(s):  
Zhujun Gao ◽  
Qiao Ding ◽  
Chongtao Ge ◽  
Robert C. Baker ◽  
Rohan V. Tikekar ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Synergistic Effects ◽  
Brain Heart Infusion ◽  
Similar Treatment ◽  
Log Reduction ◽  
Synergistic Enhancement ◽  
Foodborne Pathogenic Bacteria

ABSTRACT While high temperature heat treatments can efficiently reduce pathogen levels, they also affect the quality and nutritional profile of foods, as well as increase the cost of processing. The food additive butyl para-hydroxybenzoate (BPB) was investigated for its potential to synergistically enhance the thermal inactivation at mild heating temperatures (54 – 58 ºC). Four foodborne pathogenic bacteria, Cronobacter sakazakii , Salmonella enterica serotype Typhimurium, attenuated Escherichia coli O157:H7 and Listeria monocytogenes, were cultured to early stationary phase and then subjected to mild heating in a model food matrix (Brain Heart Infusion) containing low levels BPB (≤ 125 ppm). The heating temperature used with each bacterium was selected based on the temperature that would yield an approximate 1 – 2 log reduction over 15 min heating in BHI without BPB using a submerged coil apparatus. The inclusion of BPB at concentrations ≤ 125 ppm resulted in significant enhancement of thermal inactivation, achieving 5 – > 6 log reductions of the Gram-negative strains and D-values of < 100 sec. Listeria monocytogenes achieved at 3 – 4 log reduction with a similar treatment. No significant inactivation was noted in the absence of the mild heating for the same time period. This study provides an additional proof of concept that low temperature inactivation of foodborne pathogens can be realized by synergistic enhancement of thermal inactivation by food components that affect microbial cell membranes.

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.

Thermal Inactivation of Listeria monocytogenes in Crab Meat

2018 ◽  
Vol 81 (12) ◽  
pp. 2003-2006 ◽  
Author(s):  
A. MCDERMOTT ◽  
P. WHYTE ◽  
N. BRUNTON ◽  
D. J. BOLTON
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Inactivation ◽  
Bacterial Pathogen ◽  
Limited Information ◽  
Tryptone Soya Broth ◽  
Complete Destruction ◽  
Model Matrix ◽  
Seafood Products ◽  
D Values ◽  
Crab Meat

ABSTRACT Listeria monocytogenes is an important bacterial pathogen in seafood products, but limited information is currently available on the thermal resistance of relevant isolates in seafood. Thermal inactivation studies were undertaken (i) to provide much needed thermal inactivation data for L. monocytogenes in crab meat and (ii) to investigate whether tryptone soya broth (TSB) is representative of crab meat in thermal inactivation studies involving L. monocytogenes. D-values were obtained for a cocktail of two crab isolates (serotypes 1/2a and 4b) at 50, 55, and 60°C. In crab meat, D-values were 174.4, 28.2, and 1.6 min, respectively. Similar D-values of 176.4, 28.8, and 1.4 min were obtained in TSB. The corresponding z-values were 4.9°C (crab meat) and 4.8°C (TSB), respectively. The conclusions were that (i) current pasteurization conditions (e.g., 70°C for 2 min) would achieve complete destruction of any L. monocytogenes present in crab meat and (ii) TSB could be used as a model matrix for assessing the thermal inactivation of L. monocytogenes in crab meat.

Strain variability in growth and thermal inactivation characteristics of Listeria monocytogenes strains after acid adaptation

2021 ◽  
Author(s):  
Tian Shihong ◽  
Wang Xiang ◽  
Wu Yufan ◽  
Liu Hongmei ◽  
Bai Li ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Inactivation ◽  
Growth Parameters ◽  
Inactivation Kinetics ◽  
Predictive Microbiology ◽  
Acid Adaptation ◽  
Lag Times ◽  
D Values ◽  
Different Strains ◽  
Strain Variability

Given the importance of strain variability to predictive microbiology and risk assessment, the present study aimed to quantify the magnitude of strain variability in growth and thermal inactivation kinetics behaviors after acid adaptation. Thirty-three Listeria monocytogenes strains were exposed to acid-adapted tryptic soy broth with yeast extract and nonacid-adapted TSB-YE (pH 7.0) for 20 hours. Then, the growth parameters of these adapted and non-adapted strains that grew in non-buffered TSB-YE at 25℃ were estimated. The tested strains were inactivated at 60°C in non-buffered broth to obtain the heat resistance parameters. The results revealed that strain variability was present in the growth and thermal inactivation characteristics. The maximum specific growth rate ( μ max ) ranged within 0.21-0.44 and 0.20-0.45 h -1 after acid and non-acid adaptation, respectively. The lag times ( λ ) were 0.69-2.56 and 0.24-3.36 hours for acid-adapted and non-acid adapted cells, respectively. The apparent D -values at 60°C ( D 60 -values) of the pathogen ranged within 0.56-3.93 and 0.52-3.63 minutes for the presence and absence of acid adaptation condition, respectively. Acid adaptation increased the magnitude of strain variability in the thermal inactivation characteristics of the organism ( P <0.05), with the coefficient of variation (CV) increasing to 0.17, while acid adaptation did not significantly influence the variabilities in the growth parameters of the tested strains ( P ≥0.05). Furthermore, the subsequent growth behaviors of all strains did not exhibit significant changes ( P >0.05) after exposure to acidic broth. However, the thermal resistance of most of the tested strains (25/33) increased ( P <0.05) after growing in acid-adapted broth. The relevant data generated in the present study can be used to describe the strain variability in predictive microbiology, and deeply understand the behavior responses of different strains to acid adaptation.

Interaction of Citric Acid Concentration and pH on the Kinetics of Listeria monocytogenes Inactivation

1994 ◽  
Vol 57 (7) ◽  
pp. 567-570 ◽  
Author(s):  
ROBERT L. BUCHANAN ◽  
MARSHA H. GOLDEN
Keyword(s):  
Listeria Monocytogenes ◽  
Citric Acid ◽  
Acid Concentration ◽  
Brain Heart Infusion ◽  
Citric Acid Concentration ◽  
The Media ◽  
Low Levels ◽  
D Values ◽  
Kinetics Of ◽  
Acetic Acids

The effects and interactions between pH and CitriC acid concentration on the inactivation of Listeria monocytogenes was determined using a three-strain mixture. Citric acid/sodium citrate combinations were added to brain heart infusion (BHI) broth to achieve concentrations of 0.1, 0.5, 1.0 and 2.0 M in conjunction with pH values of 4, 5, 6 and 7. The media were dispensed in 20-ml portions in dilution bottles, inoculated to approximately 108 CFU/ml, and incubated at 28°C. Survivor curves were generated using a linear model incorporating a lag term, and D-values and “time to 4-D inactivation” values were calculated. The results were compared against control cultures in which the pH was modified using hydrochloric acid (HCI). The rate of inactivation was dependent on both the pH and concentration of citric acid. Low levels of citric acid were protective, particularly at pH 5 and 6. At higher concentrations, a distinct anion effect was observed as compared to the HCl controls, with inactivation rates being correlated with the completely undissociated form of the acid. Comparison of the kinetic data with earlier results with lactic and acetic acids suggests that citric acid has both protective and bactericidal activity against L. monocytogenes, which involve different modes of action.

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