scholarly journals Identifying suitableListeria innocuastrains as surrogates forListeria monocytogenesfor horticultural products

2019 ◽  
Author(s):  
Vathsala Mohan ◽  
Reginald Wibisono ◽  
Lana de Hoop ◽  
Graeme Summers ◽  
Graham C Fletcher
Keyword(s):  
Listeria Monocytogenes ◽  
Thermal Inactivation ◽  
Listeria Innocua ◽  
Peroxyacetic Acid ◽  
Safety Risks ◽  
Horticultural Products ◽  
Different Strains ◽  
The Individual ◽  
Uv C ◽  
Strain Dependent

AbstractWe conducted a laboratory-based study testing nineListeria innocuastrains independently and a cocktail of 11Listeria monocytogenesstrains. The aim was to identify suitableL. innocuastrain(s) to modelL. monocytogenesin inactivation experiments. Three separate inactivation procedures and a hurdle combination of the three were employed: thermal inactivation (55°C), UV-C irradiation (245 nm) and chemical sanitiser (Tsunami™ 100, a mixture of acetic acid, peroxyacetic acid and hydrogen peroxide). The responses were strain dependent in the case ofL. innocuawith different strains responding differently to different regimes.L. innocuaisolates generally responded differently to theL. monocytogenescocktail and had different responses among themselves. In the thermal inactivation treatment, inactivation of all strains including theL. monocytogenescocktail plateaued after 120 minutes. Chemical sanitiser, inactivation could be achieved at concentrations of 10 and 20 ppm with inactivation increasing with contact time up to 8 minutes, beyond which there was no significant benefit. Although most of theL. innocuastrains in the study responded similarly toL. monocytogeneswhen subjected to a single inactivation treatment, when the treatments were applied as hurdle, allL. innocuastrains except PFR16D08 were more sensitive than theL. monocytogenescocktail. PFR16D08 almost matched the resistance of theL. monocytogenescocktail but was much more resistant to the individual treaments. A cocktail of twoL. innocuastrains (PFR 05A07 and PFR 05A10) had the closest responses to the hurdle treatment to those of theL. monocytogenescocktail and is therefore recommended for hurdle experiments.ImportanceOwing to researcher safety risks it is often difficult to use actual pathogens, such asListeria monocytogenes, to explore different inactivation procedures under field conditions. Organisms that are closely related to the pathogen but without its virulence are therefore used as surrogates for the actual pathogen. However, this assumes that the surrogate will behave in a similar manner to the pathogen and it is difficult to predict the responses of the surrogate compared to the actual pathogen. This study compares the responses of individual and combined “cocktails” of strains of non-pathogenicListeria innocuato different inactivation procedures when compared to the response of a cocktail ofL. monocytogenes. Our study highlights the importance of evaluating a number of strains when choosing surrogates.

scholarly journals Thermal inactivation and growth potential of Listeria monocytogenes in smoked tench

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Raffaella Branciari ◽  
Andrea Valiani ◽  
Raffaella Franceschini ◽  
David Ranucci ◽  
Alessia Lupattelli ◽  
...  
Keyword(s):  
Experimental Study ◽  
Listeria Monocytogenes ◽  
Thermal Inactivation ◽  
Challenge Test ◽  
Listeria Innocua ◽  
Growth Potential ◽  
Post Processing ◽  
Colony Forming Unit ◽  
Post Process ◽  
Hygiene Measures

An experimental study for the evaluation of <em>Listeria monocytogenes</em> inactivation during a hot smoking process in tench was performed using <em>Listeria innocua</em> strains. Furthermore, the survival of <em>L. monocytogenes</em> in smoked tench was determined after post-processing in contaminated samples, evaluating the growth potential during storage. <em>L. innocua</em> was not detected after the smoking process. In the challenge test, the growth potential of <em>L. monocytogenes</em> was 5.68 log colony forming unit g<sup>−1</sup>. The results showed that hot smoking at an inner temperature around 72°C is able to eliminate the microorganism. Nevertheless, the product is able to support the growth of the pathogen if post-process contamination occurs, as the food is suitable for <em>Listeria</em> multiplication. Product recontamination should be prevented by means of appropriate application of hygiene measures.

Isolation of Listeria spp. from Feces of Feedlot Cattle

1993 ◽  
Vol 56 (2) ◽  
pp. 102-105 ◽  
Author(s):  
G. R. SIRAGUSA ◽  
J. S. DICKSON ◽  
E. K. DANIELS
Keyword(s):  
Listeria Monocytogenes ◽  
Beef Cattle ◽  
Feedlot Cattle ◽  
Listeria Innocua ◽  
Composite Sample ◽  
The Individual ◽  
Composite Samples

Healthy feedlot beef cattle were surveyed for the presence of Listeria spp. in fecal grab samples taken over 3 months. Composite samples were made from 224 individual animals each month. Listeria monocytogenes was isolated from one composite sample (4%) from the first sampling and not from the subsequent two. Listeria innocua was found in composite samples from all three samplings at levels of 17, 9, and 35%, respectively. From the individual samples comprising the Listeria spp.--positive composites, L. monoytogenes was isolated from one sample (3%) in the second sampling but not in the first or third samplings. L. innocua was found in 9, 8, and 10% of the individual samples comprising Listeria--positive composites in the first, second, and third samplings, respectively. The two L. monocytogenes isolates were pathogenic to mice. Further characterization of these isolates revealed atypical rhamnose fermentation patterns. These results indicate that the frequency of isolation of L. monocytogenes from feedlot beef cattle is low.

Comparative Study on the Efficacy of Bacteriophages, Sanitizers, and UV Light Treatments To Control Listeria monocytogenes on Sliced Mushrooms (Agaricus bisporus)

2015 ◽  
Vol 78 (6) ◽  
pp. 1147-1153 ◽  
Author(s):  
KAYLA MURRAY ◽  
FAN WU ◽  
RAFIA AKTAR ◽  
AZADEH NAMVAR ◽  
KEITH WARRINER
Keyword(s):  
Hydrogen Peroxide ◽  
Listeria Monocytogenes ◽  
Comparative Study ◽  
Agaricus Bisporus ◽  
Uv Light ◽  
Multiplicity Of Infection ◽  
Peroxyacetic Acid ◽  
Electrolyzed Water ◽  
Sublethal Injury ◽  
Uv C

The following reports on a comparative study on the efficacy of different decontamination technologies to decrease Listeria monocytogenes inoculated onto white sliced mushrooms and assesses the fate of residual levels during posttreatment storage under aerobic conditions at 8°C. The treatments were chemical (hydrogen peroxide, peroxyacetic acid, ozonated water, electrolyzed water, chitosan, lactic acid), biological (Listeria bacteriophages), and physical (UV-C, UV–hydrogen peroxide). None of the treatments achieved &gt;1.2 log CFU reduction in L. monocytogenes levels; bacteriophages at a multiplicity of infection of 100 and 3% (vol/vol) hydrogen peroxide were the most effective of the treatments tested. However, growth of residual L. monocytogenes during posttreatment storage attained levels equal to or greater than levels in the nontreated controls. The growth of L. monocytogenes was inhibited on mushrooms treated with chitosan, electrolyzed water, peroxyacetic acid, or UV. Yet, L. monocytogenes inoculated onto mushrooms and treated with UV–hydrogen peroxide decreased during posttreatment storage, through a combination of sublethal injury and dehydration of the mushroom surface. Although mushrooms treated with UV–hydrogen peroxide became darker during storage, the samples were visually acceptable relative to controls. In conclusion, of the treatments evaluated, UV–hydrogen peroxide holds promise to control L. monocytogenes on mushroom surfaces.

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 &lt;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 &gt;0.05) after exposure to acidic broth. However, the thermal resistance of most of the tested strains (25/33) increased ( P &lt;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.

scholarly journals Decontamination of Listeria innocua from fresh-cut broccoli using UV-C applied in water or peroxyacetic acid, and dry-pulsed light

2019 ◽  
Vol 52 ◽  
pp. 438-449 ◽  
Author(s):  
Cyrelys Collazo ◽  
Florence Charles ◽  
Ingrid Aguiló-Aguayo ◽  
Jesús Marín-Sáez ◽  
Tomás Lafarga ◽  
...  
Keyword(s):  
Listeria Innocua ◽  
Peroxyacetic Acid ◽  
Pulsed Light ◽  
Fresh Cut ◽  
Uv C

scholarly journals Identifying Suitable Listeria innocua Strains as Surrogates for Listeria monocytogenes for Horticultural Products

2019 ◽  
Vol 10 ◽  
Author(s):  
Vathsala Mohan ◽  
Reginald Wibisono ◽  
Lana de Hoop ◽  
Graeme Summers ◽  
Graham C. Fletcher
Keyword(s):  
Listeria Monocytogenes ◽  
Listeria Innocua ◽  
Horticultural Products

Vapor Phase Hydroxyl- or Chlorine-radical Treatment for Inactivating Listeria monocytogenes on Mushrooms (Agaricus bisporus) Without Negatively Affecting Quality or Shelf-life

2021 ◽  
Author(s):  
Keith Warriner ◽  
Mahdiyeh Hasani ◽  
Hongran Wang ◽  
Alisha Alisha
Keyword(s):  
Hydrogen Peroxide ◽  
Listeria Monocytogenes ◽  
Hydroxyl Radical ◽  
Vapor Phase ◽  
Negative Effects ◽  
Radical Process ◽  
Log Reduction ◽  
Radical Treatment ◽  
The Individual ◽  
Uv C

Processes based on generating vapor phase hydroxyl-radicals or chlorine-radicals were developed for inactivating Listeria monocytogenes on mushrooms without negatively affecting quality. Antimicrobial radicals were generated from the UV-C degradation of hydrogen peroxide or hypochlorite and ozone gas. Response Surface Modelling (RMS) was used to identify the interaction between the operating parameters for the hydroxyl-radical process; UV-C 254nm intensity, hydrogen peroxide concentration and ozone delivered. There was an inverse relationship between hydrogen peroxide concentration and UV-C intensity in terms of the log reduction of L. monocytogenes . The independent parameters for the chlorine-radical process were hypochlorite concentration, pH, and UV-C intensity. From predictive models, the optimal hydroxyl-radical treatment was found to be 5% v/v H 2 O 2 , 2.86 mW/cm 2 UV-C intensity (total UV-C dose 144 mJ/cm 2 ) and 16.5 mg ozone. The chlorine-radical optimal process parameters were 10 ppm hypochlorite (pH 3.0), ozone 11.0 mg and 4.60 mW/cm 2 UV-C intensity. When inoculated mushrooms were treated with the optimal hydroxyl-radical and chlorine-radical process the log CFU reduction of L. monocytogenes was found to be 2.42±0.42 and 2.61±0.30 log CFU respectively without any negative effects on mushroom quality (weight loss and Browning Index during 14 days storage at 4°C). The levels of L. monocytogenes inactivation were significantly greater compared to when the individual elements of the radical processes were applied and control using a 90 s dip in 1% v/v hydrogen peroxide. The study has demonstrated that both hydroxyl-radical and chlorine-radical vapor-phase treatments are both equally effective at inactivating L. monocytogenes on mushrooms and can be considered as a preventative control step.

A Predictive Model for the Inactivation of Listeria innocua in Cooked Poultry Products during Postpackage Pasteurization

2011 ◽  
Vol 74 (8) ◽  
pp. 1261-1267 ◽  
Author(s):  
MIN LI ◽  
ABANI PRADHAN ◽  
LISA COONEY ◽  
ANDY MAUROMOUSTAKOS ◽  
PHILIP CRANDALL ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Predictive Model ◽  
Thermal Inactivation ◽  
Hot Water ◽  
Listeria Innocua ◽  
Zone Method ◽  
Data Set ◽  
Poultry Products ◽  
Fully Cooked ◽  
Mean Square Errors

Contamination of Listeria monocytogenes in ready-to-eat poultry products poses potential risk of listeriosis to the public. To control the level of Listeria contamination, attention has been focused on the postpackage pasteurization of fully cooked poultry products. In this study, we sought to develop a model to predict the thermal inactivation of L. monocytogenes in chicken drumettes during postpackage hot water pasteurization. Fully cooked chicken drumettes were inoculated with Listeria innocua as a surrogate microorganism for Listeria monocytogenes, vacuum packaged, and treated in hot water baths at 60, 70, 80, and 90°C for different heating times. Experimental results showed that a 7-log CFU/g reduction of L. innocua occurred at 54, 28, 18, and 10 min at 60, 70, 80, and 90°C, respectively. The Weibull model was used to fit the survival curves of L. innocua at each heating temperature. The root mean square errors and residual plots indicated good agreements between the predicted and observed values. The predictive model was further validated by predicting a new data set generated in the pilot-plant tests. Model performance was evaluated by the acceptable prediction zone method, and the results indicated that the percentages of acceptable prediction errors were 100, 100, 82.4, and 87.5% at 60, 70, 80 and 90°C, respectively, which were all greater than the threshold acceptable value of 70%, indicating good performance of the model. The developed predictive model can be used as a tool to predict thermal inactivation behaviors of L. monocytogenes in ready-to-eat chicken drumettes products.

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