A novel microfluidic mixer-based approach for determining inactivation kinetics of Escherichia coli O157:H7 in chlorine solutions

2015 ◽  
Vol 49 ◽  
pp. 152-160 ◽  
Author(s):  
Boce Zhang ◽  
Yaguang Luo ◽  
Bin Zhou ◽  
Qin Wang ◽  
Patricia D. Millner
Keyword(s):  
Escherichia Coli ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
Microfluidic Mixer ◽  
Kinetics Of

Viability of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in Yellow Fat Spreads as Affected by Storage Temperature

2003 ◽  
Vol 66 (4) ◽  
pp. 549-558 ◽  
Author(s):  
SARAH L. HOLLIDAY ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Storage Temperature ◽  
Salt Content ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Inhibition Of Growth ◽  
Time Required ◽  
Kinetics Of

A study was conducted to characterize the survival and inactivation kinetics of a five-serotype mixture of Salmonella (6.23 to 6.55 log10 CFU per 3.5-ml or 4-g sample), a five-strain mixture of Escherichia coli O157:H7 (5.36 to 6.14 log10 CFU per 3.5-ml or 4-g sample), and a six-strain mixture of Listeria monocytogenes (5.91 to 6.18 log10 CFU per 3.5-ml or 4-g sample) inoculated into seven yellow fat spreads (one margarine, one butter-margarine blend, and five dairy and nondairy spreads and toppings) after formulation and processing and stored at 4.4, 10, and 21°C for up to 94 days. Neither Salmonella nor E. coli O157:H7 grew in any of the test products. The time required for the elimination of each pathogen depended on the product and the storage temperature. Death was more rapid at 21°C than at 4.4 or 10°C. Depending on the product, the time required for the elimination of viable cells at 21°C ranged from 5 to 7 days to >94 days for Salmonella, from 3 to 5 days to 28 to 42 days for E. coli O157:H7, and from 10 to 14 days to >94 days for L. monocytogenes. Death was most rapid in a water-continuous spray product (pH 3.66, 4.12% salt) and least rapid in a butter-margarine blend (pH 6.66, 1.88% salt). E. coli O157:H7 died more rapidly than did Salmonella or L. monocytogenes regardless of storage temperature. Salmonella survived longer in high-fat (≥61%) products than in products with lower fat contents. The inhibition of growth is attributed to factors such as acidic pH, salt content, the presence of preservatives, emulsion characteristics, and nutrient deprivation. L. monocytogenes did not grow in six of the test products, but its population increased between 42 and 63 days in a butter-margarine blend stored at 10°C and between 3 and 7 days when the blend was stored at 21°C. On the basis of the experimental parameters examined in this study, traditional margarine and spreads not containing butter are not “potentially hazardous foods” in that they do not support the growth of Salmonella, E. coli O157:H7, or L. monocytogenes.

Inactivation Kinetics of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Ready-to-Eat Sliced Ham by Near-Infrared Heating at Different Radiation Intensities

2014 ◽  
Vol 77 (7) ◽  
pp. 1224-1228 ◽  
Author(s):  
JAE-WON HA ◽  
DONG-HYUN KANG
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Logistic Model ◽  
Near Infrared ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
Survival Curves ◽  
Serovar Typhimurium ◽  
Kinetics Of

The aim of this study was to investigate the inactivation kinetics of Salmonella enterica serovar Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes on ready-to-eat sliced ham by near-infrared (NIR) heating as a function of the processing parameter, radiation intensity. Precooked ham slices inoculated with the three pathogens were treated at different NIR intensities (ca. 100, 150, and 200 μW/cm2/nm). An increase in the applied radiation intensity resulted in a gradual increase of inactivation of all pathogens. The survival curves of the three pathogens exhibited both shoulder and tailing behavior at all light intensities. Among nonlinear models, the Weibull distribution and log-logistic model were used to describe the experimental data, and the statistical results (mean square error and R2 values) indicated the suitability of the model for prediction. The log-logistic model more accurately described survival curves of the three pathogens than did the Weibull distribution at all radiation intensities. The output of this study and the proposed kinetics model would be beneficial to the deli meat industry for selecting the optimum processing conditions of NIR heating to meet the target pathogen inactivation on ready-to-eat sliced ham.

Thermal and Starvation Stress Response of Escherichia coli O157:H7 Isolates Selected from Agricultural Environments

2016 ◽  
Vol 79 (10) ◽  
pp. 1673-1679 ◽  
Author(s):  
ACHYUT ADHIKARI ◽  
ANDY BARY ◽  
CRAIG COGGER ◽  
CALEB JAMES ◽  
GÜLHAN ÜNLÜ ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Heat Stress ◽  
Stress Response ◽  
Weibull Model ◽  
Stress Conditions ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
Starvation Stress ◽  
E Coli ◽  
Response To Stress

ABSTRACT Pathogens exposed to agricultural production environments are subject to multiple stresses that may alter their survival under subsequent stress conditions. The objective of this study was to examine heat and starvation stress response of Escherichia coli O157:H7 strains isolated from agricultural matrices. Seven E. coli O157:H7 isolates from different agricultural matrices—soil, compost, irrigation water, and sheep manure—were selected, and two ATCC strains were used as controls. The E. coli O157:H7 isolates were exposed to heat stress (56°C in 0.1% peptone water for up to 1 h) and starvation (in phosphate-buffered saline at 37°C for 15 days), and their survival was examined. GInaFiT freeware tool was used to perform regression analyses of the surviving populations. The Weibull model was identified as the most appropriate model for response of the isolates to heat stress, whereas the biphasic survival curves during starvation were fitted using the double Weibull model, indicating the adaptation to starvation or a resistant subpopulation. The inactivation time during heating to achieve the first decimal reduction time (δ) calculated with the Weibull parameters was the highest (45 min) for a compost isolate (Comp60A) and the lowest (28 min) for ATCC strain 43895. Two of the nine isolates (ATCC 43895 and a manure isolate) had β < 1, indicating that surviving populations adapted to heat stress, and six strains demonstrated downward concavity (β > 1), indicating decreasing heat resistance over time. The ATCC strains displayed the longest δ2 (>1,250 h) in response to starvation stress, compared with from 328 to 812 h for the environmental strains. The considerable variation in inactivation kinetics of E. coli O157:H7 highlights the importance of evaluating response to stress conditions among individual strains of a specific pathogen. Environmental isolates did not exhibit more robust response to stress conditions in this study compared with ATCC strains.

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