Inactivation Kinetics of Pathogens during Thermal Processing in Acidified Broth and Tomato Purée (pH 4.5)

2017 ◽  
Vol 80 (12) ◽  
pp. 2014-2021 ◽  
Author(s):  
Evann L. Dufort ◽  
Jonathan Sogin ◽  
Mark R. Etzel ◽  
Barbara H. Ingham
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
E Coli ◽  
Log Reduction ◽  
Tomato Puree ◽  
Weibull Models ◽  
Canned Foods ◽  
D Values ◽  
Log Linear

ABSTRACT Thermal inactivation kinetics for single strains of Shiga toxin–producing Escherichia coli (STEC), Listeria monocytogenes, and Salmonella enterica were measured in acidified tryptic soy broth (TSB; pH 4.5) heated at 54°C. Inactivation curves also were measured for single-pathogen five-strain cocktails of E. coli O157:H7, L. monocytogenes, and S. enterica heated in tomato purée (pH 4.5) at 52, 54, 56, and 58°C. Inactivation curves were fit using log-linear and nonlinear (Weibull) models. The Weibull model yields the time for a 5-log reduction (t*) and a curve shape parameter (β). Decimal reduction times (D-values) and thermal resistance constants (z-values) from the two models were compared by defining t* = 5D* for the Weibull model. When the log-linear and Weibull models match at the 5-log reduction time, then t* = 5D* = 5D and D = D*. In 18 of 20 strains heated in acidified TSB, D and D* for the two models were not significantly different, although nonlinearity was observed in 35 of 60 trials. Similarly, in 51 of 52 trials for pathogen cocktails heated in tomato purée, D and D* were not significantly different, although nonlinearity was observed in 31% of trials. At a given temperature, D-values for S. enterica << L. monocytogenes < E. coli O157:H7 in tomato purée (pH 4.5). When using the two models, z-values calculated from the D-values were not significantly different for a given pathogen. Across all pathogens, z-values for E. coli O157:H7 and S. enterica were not different but were significantly lower than the z-values for L. monocytogenes. These results are useful for supporting process filings for tomato-based acidified food products with pH 4.5 and below and are relevant to small processors of tomato-based acidified canned foods who do not have the resources to conduct research on and validate pathogen lethality.

Thermal Inactivation Kinetics of Three Heat-Resistant Salmonella Strains in Whole Liquid Egg

2019 ◽  
Vol 82 (9) ◽  
pp. 1465-1471 ◽  
Author(s):  
JOSHUA B. GURTLER ◽  
VIJAY K. JUNEJA ◽  
DEANA R. JONES ◽  
ANUJ PUROHIT
Keyword(s):  
Survival Data ◽  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Glass Capillary ◽  
Circulating Water ◽  
Log Reduction ◽  
Heat Resistant ◽  
Weibull Models ◽  
D Values ◽  
Log Linear

ABSTRACT The heat resistance of three heat-resistant strains of Salmonella was determined in whole liquid egg (WLE). Inoculated samples in glass capillary tubes were completely immersed in a circulating water bath and held at 56, 58, 60, 62, and 64°C for predetermined lengths of time. The recovery medium was tryptic soy agar with 0.1% sodium pyruvate and 50 ppm of nalidixic acid. Survival data were fitted using log-linear, log-linear with shoulder, and Weibull models using GInaFiT version 1.7. Based on the R2 and mean square error, the log-linear with shoulder and Weibull models consistently produced a better fit to Salmonella survival curves obtained at these temperatures. Contaminated WLE must be heated at 56, 60, and 64°C for at least 33.2, 2.7, and 0.31 min, respectively, to achieve a 4-log reduction of Salmonella; 39.0, 3.1, and 0.34 min, respectively, for a 5-log reduction; and 45.0, 3.5, and 0.39 min, respectively, for a 6-log reduction. The z-values calculated from the D-values were 3.67 and 4.18°C for the log-linear with shoulder and Weibull models, respectively. Thermal death times presented in this study will be beneficial for WLE distributors and regulatory agencies when designing pasteurization processes to effectively eliminate Salmonella in WLE, thereby ensuring the microbiological safety of the product.

scholarly journals Evaluation of the Thermal Inactivation of a Salmonella Serotype Oranienburg Strain During Cocoa Roasting at Conditions Relevant to the Fine Chocolate Industry

2021 ◽  
Vol 12 ◽  
Author(s):  
Runan Yan ◽  
Gabriella Pinto ◽  
Rebecca Taylor-Roseman ◽  
Karen Cogan ◽  
Greg D’Alesandre ◽  
...  
Keyword(s):  
Foodborne Pathogens ◽  
Thermal Inactivation ◽  
Linear Models ◽  
Control Point ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Critical Control Point ◽  
Chocolate Industry ◽  
Weibull Models ◽  
Log Linear

Cocoa roasting produces and enhances distinct flavor of chocolate and acts as a critical control point for inactivation of foodborne pathogens in chocolate production. In this study, the inactivation kinetics of Salmonella enterica subsp. enterica serotype Oranienburg strain was assessed on whole cocoa beans using roasting protocols relevant to the fine chocolate industry. Beans were inoculated with 107–108 log10 CFU/bean of Salmonella Oranienburg and roasted at 100–150°C for 2–100 min. A greater than 5 log10 reduction of S. Oranienburg was experimentally achieved after 10-min roasting at 150°C. Data were fitted using log-linear and Weibull models. The log-linear models indicated that the roasting times (D) needed to achieve a decimal reduction of Salmonella at 100, 110, 115, 120, 130, and 140°C were 33.34, 18.57, 12.92, 10.50, 4.20, and 1.90 min, respectively. A Weibull model indicated a decrease in the Salmonella inactivation rate over time (β < 1). Statistical analysis indicated that the Weibull model fitted the data better compared to a log-linear model. These data demonstrate the efficacy of cocoa roasting in inactivation of Salmonella and may be used to guide food safety decision-making.

Modeling Penicillium expansum Resistance to Thermal and Chlorine Treatments

2009 ◽  
Vol 72 (12) ◽  
pp. 2618-2622 ◽  
Author(s):  
BEATRIZ C. M. SALOMÃO ◽  
JOHN J. CHUREY ◽  
GLÁUCIA M. F. ARAGÃO ◽  
RANDY W. WOROBO
Keyword(s):  
Apple Juice ◽  
Weibull Model ◽  
Superior Performance ◽  
Penicillium Expansum ◽  
Heat Inactivation ◽  
Survival Curves ◽  
Biphasic Model ◽  
Log Reduction ◽  
Weibull Models ◽  
D Values

Apples and apple products are excellent substrates for Penicillium expansum to produce patulin. In an attempt to avoid excessive levels of patulin, limiting or reducing P. expansum contamination levels on apples designated for storage in packinghouses and/or during apple juice processing is critical. The aim of this work was (i) to determine the thermal resistance of P. expansum spores in apple juice, comparing the abilities of the Bigelow and Weibull models to describe the survival curves and (ii) to determine the inactivation of P. expansum spores in aqueous chlorine solutions at varying concentrations of chlorine solutions, comparing the abilities of the biphasic and Weibull models to fit the survival curves. The results showed that the Bigelow and Weibull models were similar for describing the heat inactivation data, because the survival curves were almost linear. In this case, the concept of D- and z-values could be used, and the D-values obtained were 10.68, 6.64, 3.32, 1.14, and 0.61 min at 50, 52, 54, 56, and 60°C, respectively, while the z-value was determined to be 7.57°C. For the chlorine treatments, although the biphasic model gave a slightly superior performance, the Weibull model was selected, considering the parsimony principle, because it has fewer parameters than the biphasic model has. In conclusion, the typical pasteurization regimen used for refrigerated apple juice (71°C for 6 s) is capable of achieving a 6-log reduction of P. expansum spores.

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.

Thermal Inactivation of Human Norovirus Surrogates in Spinach and Measurement of Its Uncertainty

2014 ◽  
Vol 77 (2) ◽  
pp. 276-283 ◽  
Author(s):  
HAYRIYE BOZKURT ◽  
DORIS H. D'SOUZA ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Murine Norovirus ◽  
Order Model ◽  
Human Norovirus ◽  
Test Volume ◽  
Total Uncertainty ◽  
First Order ◽  
D Values

Leafy greens, including spinach, have potential for human norovirus transmission through improper handling and/or contact with contaminated water. Inactivation of norovirus prior to consumption is essential to protect public health. Because of the inability to propagate human noroviruses in vitro, murine norovirus (MNV-1) and feline calicivirus (FCV-F9) have been used as surrogates to model human norovirus behavior under laboratory conditions. The objectives of this study were to determine thermal inactivation kinetics of MNV-1 and FCV-F9 in spinach, compare first-order and Weibull models, and measure the uncertainty associated with the process. D-values were determined for viruses at 50, 56, 60, 65, and 72°C in 2-ml vials. The D-values calculated from the first-order model (50 to 72°C) ranged from 0.16 to 14.57 min for MNV-1 and 0.15 to 17.39 min for FCV-9. Using the Weibull model, the tD for MNV-1 and FCV-F9 to destroy 1 log (D = 1) at the same temperatures ranged from 0.22 to 15.26 and 0.27 to 20.71 min, respectively. The z-values determined for MNV-1 were 11.66 ± 0.42°C using the Weibull model and 10.98 ± 0.58°C for the first-order model and for FCV-F9 were 10.85 ± 0.67°C and 9.89 ± 0.79°C, respectively. There was no difference in D- or z-value using the two models (P >0.05). Relative uncertainty for dilution factor, personal counting, and test volume were 0.005, 0.0004, and ca. 0.84%, respectively. The major contribution to total uncertainty was from the model selected. Total uncertainties for FCV-F9 for the Weibull and first-order models were 3.53 to 7.56% and 11.99 to 21.01%, respectively, and for MNV-1, 3.10 to 7.01% and 13.14 to 16.94%, respectively. Novel and precise information on thermal inactivation of human norovirus surrogates in spinach was generated, enabling more reliable thermal process calculations to control noroviruses. The results of this study may be useful to the frozen food industry in designing blanching processes for spinach to inactivate or control noroviruses.

Thermal Inactivation Kinetics of Sporolactobacillus nakayamae Spores, a Spoilage Bacterium Isolated from a Model Mashed Potato–Scallion Mixture

2016 ◽  
Vol 79 (9) ◽  
pp. 1482-1489
Author(s):  
HAYRIYE BOZKURT ◽  
JAIRUS R. D. DAVID ◽  
RYAN J. TALLEY ◽  
D. SCOTT LINEBACK ◽  
P. MICHAEL DAVIDSON
Keyword(s):  
Heat Resistance ◽  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Order Model ◽  
First Order ◽  
Different Temperatures ◽  
Spoilage Bacterium ◽  
D Values ◽  
Kinetics Of

ABSTRACT Sporolactobacillus species have been occasionally isolated from spoiled foods and environmental sources. Thus, food processors should be aware of their potential presence and characteristics. In this study, the heat resistance and influence of the growth and recovery media on apparent heat resistance of Sporolactobacillus nakayamae spores were studied and described mathematically. For each medium, survivor curves and thermal death curves were generated for different treatment times (0 to 25 min) at different temperatures (70, 75, and 80°C) and Weibull and first-order models were compared. Thermal inactivation data for S. nakayamae spores varied widely depending on the media formulations used, with glucose yeast peptone consistently yielding the highest D-values for the three temperatures tested. For this same medium, the D-values ranged from 25.24 ± 1.57 to 3.45 ± 0.27 min for the first-order model and from 24.18 ± 0.62 to 3.50 ± 0.24 min for the Weibull model at 70 and 80°C, respectively. The z-values determined for S. nakayamae spores were 11.91 ± 0.29°C for the Weibull model and 11.58 ± 0.43°C for the first-order model. The calculated activation energy was 200.5 ± 7.3 kJ/mol for the first-order model and 192.8 ± 22.1 kJ/mol for the Weibull model. The Weibull model consistently produced the best fit for all the survival curves. This study provides novel and precise information on thermal inactivation kinetics of S. nakayamae spores that will enable reliable thermal process calculations for eliminating this spoilage bacterium.

Desiccation and Thermal Resistance of Escherichia coli O121 in Wheat Flour

2019 ◽  
Vol 82 (8) ◽  
pp. 1308-1313 ◽  
Author(s):  
QUINCY J. SUEHR ◽  
NATHAN M. ANDERSON ◽  
SUSANNE E. KELLER
Keyword(s):  
Escherichia Coli ◽  
Thermal Resistance ◽  
Wheat Flour ◽  
Shiga Toxin ◽  
Salmonella Enteritidis ◽  
Thermal Inactivation ◽  
The United States ◽  
Inactivation Kinetics ◽  
E Coli ◽  
D Values

ABSTRACT Non-O157 Shiga toxin–producing Escherichia coli infections have recently been associated with wheat flour on two separate accounts in the United States and Canada. However, there is little information regarding the thermal resistance and longevity of non-O157 Shiga toxin–producing Escherichia coli during storage in low-moisture environments. The objectives of this study were to determine the thermal inactivation kinetics of E. coli O121 in wheat flour and to compare the thermal inactivation rates with those of other pathogens. Wheat flour, inoculated with E. coli O121, was equilibrated at 25°C to a water activity of 0.45 in a humidity-controlled conditioning chamber. Inoculated samples were treated isothermally at 70, 75, and 80°C, and posttreatment population survivor ratios were determined by plate counting. D- and z-values calculated with a log-linear model, were compared with those obtained in other studies. At 70, 75, and 80°C, the D-values for E. coli O121 were 18.16 ± 0.96, 6.47 ± 0.50, and 4.58 ± 0.40 min, respectively, and the z-value was 14.57 ± 2.21°C. Overall, E. coli O121 was observed to be slightly less thermally resistant than what has been previously reported for Salmonella Enteritidis PT30 in wheat flour as measured under the same conditions with the same methods.

Thermal Inactivation Kinetics of Salmonella and Enterococcus faecium NRRL-B2354 on whole chia seeds (Salvia hispanica L.)

2021 ◽  
Author(s):  
Soon Kiat Lau ◽  
Rajendra Panth ◽  
Byron D Chaves ◽  
Curtis L Weller ◽  
Jeyamkondan Subbiah
Keyword(s):  
Enterococcus Faecium ◽  
Thermal Inactivation ◽  
Fatty Acid Content ◽  
Information Criterion ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Primary Model ◽  
Log Linear ◽  
Kinetics Of ◽  
Thermal Pasteurization

Intervention technologies for inactivating Salmonella in whole chia seeds are currently limited. The determination of the thermal inactivation kinetics of Salmonella o n chia seeds and selection of an appropriate nonpathogenic surrogate will provide a knowledge foundation for selecting and optimizing thermal pasteurization processes for chia seeds. In this study, chia seed samples from three separate production lots were inoculated with a five strain Salmonella cocktail or Enterococcus faecium NRRL-B2354 and equilibrated to 0.53 aw at room temperature (25 °C). After equilibration for at least three days, the inoculated seeds were subjected to isothermal treatments at 80, 85, or 90 °C. Samples were taken out at six timepoints and enumerated for survivors. Initial dilution of whole chia seeds was performed in a filter bag at a 1:30 ratio after it was shown to have similar recovery to grinding the seeds. Survivor data were fitted to consolidated models consisting of a primary model (log-linear or Weibull) and one secondary model (Bigelow). E. faecium exhibited higher thermal resistance than Salmonella , suggesting its suitability as a conservative nonpathogenic surrogate. The Weibull model was a better fit for the survivor data than the log-linear model for both bacteria due to its lower root mean square error and corrected Akaike’s Information Criterion values. Measurements of lipid oxidation and fatty acid content indicated a few statistically different values compared to the control samples, but the overall difference in magnitudes were relatively small. The thermal inactivation kinetics of Salmonella and E. faecium o n chia seeds as presented in this study can serve as a basis for developing thermal pasteurization processes for chia seeds.

Thermal Inactivation Kinetics of Salmonella spp. within Intact Eggs Heated Using Humidity-Controlled Air

2001 ◽  
Vol 64 (7) ◽  
pp. 934-938 ◽  
Author(s):  
R. E. BRACKETT ◽  
J. D. SCHUMAN ◽  
H. R. BALL ◽  
A. J. SCOUTEN
Keyword(s):  
Thermal Inactivation ◽  
Inactivation Kinetics ◽  
Glass Capillary ◽  
Salmonella Spp ◽  
Shell Eggs ◽  
Log Reduction ◽  
Liquid Whole Egg ◽  
D Values ◽  
Kinetics Of ◽  
Whole Egg

The heat resistance of six strains of Salmonella (including Enteritidis, Heidelberg, and Typhimurium) in liquid whole egg and shell eggs was determined. Decimal reduction times (D-values) of each of the six strains were determined in liquid whole egg heated at 56.7°C within glass capillary tubes immersed in a water bath. D-values ranged from 3.05 to 4.09 min, and significant differences were observed between the strains tested (α = 0.05). In addition, approximately 7 log10 CFU/g of a six-strain cocktail was inoculated into the geometric center of raw shell eggs and the eggs heated at 57.2°C using convection currents of humidity-controlled air. D-values of the pooled salmonellae ranged from 5.49 to 6.12 min within the center of intact shell eggs. A heating period of 70 min or more resulted in no surviving salmonellae being detected (i.e., an 8.7-log reduction per egg).

Ultraviolet inactivation of bacteria and model viruses in coconut water using a collimated beam system

2019 ◽  
Vol 25 (7) ◽  
pp. 562-572 ◽  
Author(s):  
Manreet S Bhullar ◽  
Ankit Patras ◽  
Agnes Kilonzo-Nthenge ◽  
Bharat Pokharel ◽  
Michael Sasges
Keyword(s):  
Pathogenic Bacteria ◽  
Microbial Inactivation ◽  
Coconut Water ◽  
Inactivation Kinetics ◽  
E Coli ◽  
Log Reduction ◽  
Ultraviolet C ◽  
Log Linear ◽  
Kinetics Of ◽  
Collimated Beam

This study investigated the effect of ultraviolet-C irradiation on the inactivation of microorganisms in coconut water, a highly opaque liquid food (1.01 ± 0.018 absorption coefficient). Ultraviolet-C inactivation kinetics of two bacteriophages (MS2, T1UV) and three surrogate bacteria ( Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes) in 0.1% (w/v) peptone and coconut water were investigated. Ultraviolet-C irradiation at 254 nm was applied to stirred samples, using a collimated beam device. A series of known ultraviolet-C doses (0–40 mJ cm−2) were applied for ultraviolet-C treatment except for MS2 where higher doses were delivered (100 mJ cm−2). Inactivation levels of all organisms were proportional to ultraviolet-C dose. At the highest dose of 40 mJ cm−2, three surrogates of pathogenic bacteria were inactivated by more than 5-log10 (p < 0.05) in 0.1% (w/v) peptone and coconut water. Results showed that ultraviolet-C irradiation effectively inactivated bacteriophage and surrogate bacteria in highly opaque coconut water. The log reduction kinetics of microorganisms followed log-linear and exponential models with higher R2 (>0.95) and low root mean square error values. The D10 values of 3, 5.48, and 4.58 mJ cm−2 were obtained from the inactivation of E. coli, S. Typhimurium, and L. monocytogenes, respectively. Models for predicting log reduction as a function of ultraviolet-C irradiation dose were found to be significant (p < 0.05). Fluid optics were the key controlling parameters for efficient microbial inactivation. Therefore, the ultraviolet-C dose must be calculated not only from the incident ultraviolet-C intensity but must also consider the attenuation in the samples. The results from this study imply that adequate log reduction of vegetative cells and model viruses is achievable in coconut water and suggested significant potential for ultraviolet-C treatment of other liquid foods.

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