Control Escherichia coli O157:H7 growth on sprouting brassicacae seeds with high acoustic power density (APD) ultrasound plus mild heat and calcium-oxide antimicrobial spray

Food Control ◽  
2021 ◽  
pp. 108482
Author(s):  
Mengyi Dong ◽  
Hee Kyung Park ◽  
Yirong Wang ◽  
Hao Feng
Keyword(s):  
Escherichia Coli ◽  
Power Density ◽  
Calcium Oxide ◽  
Acoustic Power ◽  
Escherichia Coli O157 ◽  
Mild Heat

Nucleic Acid Persistence in Heat-Killed Escherichia coli O157:H7 from Contaminated Skim Milk†

1999 ◽  
Vol 62 (8) ◽  
pp. 839-844 ◽  
Author(s):  
JOHN L. MCKILLIP ◽  
LEE-ANN JAYKUS ◽  
MARYANNE DRAKE
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Nucleic Acid ◽  
Dna Sequences ◽  
Skim Milk ◽  
Escherichia Coli O157 ◽  
Rt Pcr ◽  
Lower Efficiency ◽  
Time Points ◽  
Mild Heat

Polymerase chain reaction (PCR) and reverse transcriptase (RT)-PCR using primers targeting 16S rRNA sequences in Escherichia coli O157:H7 were applied to monitor the stability of rDNA and rRNA in cells killed by mild heat treatment (60°C) in skim milk. Serial dilutions of purified RNA and DNA from E. coli 0157:H7 in skim milk were amplified by RT-PCR or PCR, respectively, before heat treatment and at time points 0, 6, 12, 24, and 48 h after heating. In general, DNA-PCR provided stronger amplification signals compared to RT-PCR at the corresponding time points with the same PCR primer set, indicating a lower efficiency of RNA amplification compared to that of DNA. Ribosomal RNA and rDNA could be amplified by RT-PCR or PCR from both viable and dead cells throughout the 48-h posttreatment holding period. For RT-PCR, amplification signals decreased in intensity with increased holding time, while the efficiency of amplification of DNA sequences from dead cells remained fairly stable throughout the study. DNA persistence was greater than that of rRNA following cell death by mild heat treatment in skim milk. Skim milk did not appear to accelerate nucleic acid degradation. While rRNA was less stable than DNA, its detection by RT-PCR may not be appropriate as an exclusive indicator of cell viability in minimally processed foods.

Inactivation of Escherichia coli O157:H7 in Orange Juice Using a Combination of High Pressure and Mild Heat

1999 ◽  
Vol 62 (3) ◽  
pp. 277-279 ◽  
Author(s):  
M. LINTON ◽  
J. M. J. McCLEMENTS ◽  
M. F. PATTERSON
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Resistant Strain ◽  
Orange Juice ◽  
Escherichia Coli O157 ◽  
Pressure Treatment ◽  
Processing Conditions ◽  
E Coli ◽  
Mild Heat ◽  
Ph Range

The effect of high pressure on the survival of a pressure-resistant strain of Escherichia coli O157:H7 (NCTC 12079) in orange juice was investigated over the pH range 3.4 to 5.0. The pH of commercial, sterile orange juice was adjusted to 3.4, 3.6, 3.9, 4.5, or 5.0. The juice was then inoculated with 108 CFU ml−1 of E. coli O157:H7. The inoculated orange juice was subjected to pressure treatments of 400, 500, or 550 MPa at 20°C or 30°C to determine the conditions that would give a 6-log10 inactivation of E. coli O157:H7. A pressure treatment of 550 MPa for 5 min at 20°C produced this level of kill at pH 3.4, 3.6, 3.9, and 4.5 but not at pH 5.0. Combining pressure treatment with mild heat (30°C) did result in a 6-log10 inactivation at pH 5.0. Thus, the processing conditions (temperature and time) must be considered when pressure-treating orange juice to ensure microbiological safety.

Efficacy of UV, Acidified Sodium Hypochlorite, and Mild Heat for Decontamination of Surface and Infiltrated Escherichia coli O157:H7 on Green Onions and Baby Spinach

2012 ◽  
Vol 75 (7) ◽  
pp. 1198-1206 ◽  
Author(s):  
M. ZEKI DURAK ◽  
JOHN J. CHUREY ◽  
RANDY W. WOROBO
Keyword(s):  
Escherichia Coli ◽  
Sodium Hypochlorite ◽  
Fresh Produce ◽  
Combined Treatment ◽  
Heat Treatments ◽  
Contamination Level ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Mild Heat ◽  
The Individual

Produce-associated foodborne illnesses outbreaks have highlighted the need for more effective decontamination methods to ensure the safety of fresh produce. The main objective of this study was to evaluate the individual and combined efficacies of germicidal UV light (12.5 to 500 mJ/cm2), acidified sodium hypochlorite (ASC; 10 to 200 ppm), and mild heat (40 to 50°C) for decontaminating green onions and baby spinach infected with Escherichia coli O157:H7. Samples were inoculated by spot and dip inoculation methods to mimic surface and infiltrated E. coli O157:H7 contamination, respectively. In green onions and baby spinach, the individual efficacies of UV, ASC, and mild-heat treatments varied based on the produce type and contamination method. Following analysis of the efficacies of the single treatments, a combined treatment with 125 mJ/cm2 UV and 200 ppm of ASC at 50°C was selected for spot-inoculated green onions, and a combined treatment with 125 mJ/cm2 UV and 200 ppm of ASC at 20°C was selected for spot- and dip-inoculated baby spinach. While a >5-log reduction was achieved with the combination treatment for spot-inoculated green onions with an initial contamination level of 7.2 log CFU per spot, the same treatment reduced E. coli O157:H7 populations below the detection limit (<1 log) on green onions spot inoculated at a lower contamination level (4.3 log CFU per spot). On spot- and dip-inoculated baby spinach, the combined treatment reduced E. coli O157:H7 populations by 2.8 log CFU per spot and 2.6 log CFU/g, respectively. The combined treatment of 500 mJ/cm2 UV and 200 ppm of ASC at 50°C selected for the decontamination of dip-inoculated green onions resulted in a 2.2-log CFU/g reduction. These findings suggest that when foodborne pathogens contaminate produce and subsequently infiltrate, attach to, or become localized into protected areas, the individual or combined applications of UV, ASC, and mild-heat treatments have limited decontamination efficacies on both green onions and baby spinach (<3 log). However, treatments combining UV, ASC, and mild heat could be a promising application for reducing pathogen populations (>5 log) on E. coli O157:H7 surface-contaminated green onions. This study also highlights the importance of developing and optimizing produce-specific decontamination methods to ensure the safety of fresh produce commodities.

Efficiency of Sodium Hypochlorite, Fumaric Acid, and Mild Heat in Killing Native Microflora and Escherichia coli O157:H7, Salmonella Typhimurium DT104, and Staphylococcus aureus Attached to Fresh-Cut Lettuce

2006 ◽  
Vol 69 (2) ◽  
pp. 323-329 ◽  
Author(s):  
NOZOMI KONDO ◽  
MASATSUNE MURATA ◽  
KENJI ISSHIKI
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Salmonella Typhimurium ◽  
Sodium Hypochlorite ◽  
Fumaric Acid ◽  
Bacterial Flora ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Mild Heat ◽  
Log Reduction

The effect of the disinfectant sodium hypochlorite (NaClO), with or without mild heat (50°C) and fumaric acid, on native bacteria and the foodborne pathogens Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella Typhimurium DT104 attached to iceberg lettuce leaves was examined. The retail lettuce examined consistently harbored 6 to 7 log CFU/g of native bacteria throughout the study period. Inner leaves supported 1 to 2 log CFU/g fewer bacteria than outer leaves. About 70% of the native bacterial flora was removed by washing five times with 0.85% NaCl. S. aureus, E. coli, and Salmonella allowed to attach to lettuce leaves for 5 min were more easily removed by washing than when allowed to attach for 1 h or 2 days, with more S. aureus being removed than E. coli or Salmonella Typhimurium. An increase of time for attachment of pathogens from 5 min to 2 days leads to decreased efficiency of the washing and sanitizing treatment. Treatment with fumaric acid (50 mM for 10 min at room temperature) was the most effective, although it caused browning of the lettuce, with up to a 2-log reduction observed. The combination of 200 ppm of sodium hypochlorite and mild heat treatment at 50°C for 1 min reduced the pathogen populations by 94 to 98% (1.2- to 1.7-log reduction) without increasing browning.

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