Operating conditions for the electrolytic disinfection of process wash water from the fresh-cut industry contaminated with E. coli o157:H7

This study was conducted to investigate the effect of free chlorine concentrations in wash water on Escherichia coli O157:H7 reduction, survival, and transference during washing of fresh-cut lettuce. The effectiveness of rewashing for inactivation of E. coli O157:H7 on newly cross-contaminated produce previously washed with solutions containing an insufficient amount of chlorine also was assessed. Results indicate that solutions containing a minimum of 0.5 mg/liter free chlorine were effective for inactivating E. coli O157:H7 in suspension to below the detection level. However, the presence of 1 mg/liter free chlorine in the wash solution before washing was insufficient to prevent E. coli O157:H7 survival and transfer during washing because the introduction of cut lettuce to the wash system quickly depleted the free chlorine. Although no E. coli O157:H7 was detected in the wash solution containing 5 mg/liter free chlorine before washing a mix of inoculated and uninoculated lettuce, low numbers of E. coli O157:H7 cells were detected on uninoculated lettuce in four of the seven experimental trials. When the prewash free chlorine concentration was increased to 10 mg/liter or greater, no E. coli O157:H7 transfer was detected. Furthermore, although rewashing newly cross-contaminated lettuce in 50 mg/liter free chlorine for 30 s significantly reduced (P = 0.002) the E. coli O157:H7 populations, it failed to eliminate E. coli O157:H7 on lettuce. This finding suggests that rewashing is not an effective way to correct for process failure, and maintaining a sufficient free chlorine concentration in the wash solution is critical for preventing pathogen cross-contamination.

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Guidelines To Validate Control of Cross-Contamination during Washing of Fresh-Cut Leafy Vegetables

Journal of Food Protection ◽

10.4315/0362-028x.jfp-16-258 ◽

2017 ◽

Vol 80 (2) ◽

pp. 312-330 ◽

Cited By ~ 60

Author(s):

D. Gombas ◽

Y. Luo ◽

J. Brennan ◽

G. Shergill ◽

R. Petran ◽

...

Keyword(s):

Food Production ◽

Microbial Contamination ◽

Operating Conditions ◽

Wash Water ◽

Leafy Vegetables ◽

Cross Contamination ◽

Worst Case ◽

Preventive Control ◽

Fresh Cut ◽

The U.S

ABSTRACT The U.S. Food and Drug Administration requires food processors to implement and validate processes that will result in significantly minimizing or preventing the occurrence of hazards that are reasonably foreseeable in food production. During production of fresh-cut leafy vegetables, microbial contamination that may be present on the product can spread throughout the production batch when the product is washed, thus increasing the risk of illnesses. The use of antimicrobials in the wash water is a critical step in preventing such water-mediated cross-contamination; however, many factors can affect antimicrobial efficacy in the production of fresh-cut leafy vegetables, and the procedures for validating this key preventive control have not been articulated. Producers may consider three options for validating antimicrobial washing as a preventive control for cross-contamination. Option 1 involves the use of a surrogate for the microbial hazard and the demonstration that cross-contamination is prevented by the antimicrobial wash. Option 2 involves the use of antimicrobial sensors and the demonstration that a critical antimicrobial level is maintained during worst-case operating conditions. Option 3 validates the placement of the sensors in the processing equipment with the demonstration that a critical antimicrobial level is maintained at all locations, regardless of operating conditions. These validation options developed for fresh-cut leafy vegetables may serve as examples for validating processes that prevent cross-contamination during washing of other fresh produce commodities.

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Assessment of the Prevalence of Extended-Spectrum β-Lactamase–Producing Enterobacteriaceae in Ready-to-Eat Salads, Fresh-Cut Fruit, and Sprouts from the Swiss Market

Journal of Food Protection ◽

10.4315/0362-028x.jfp-15-018 ◽

2015 ◽

Vol 78 (6) ◽

pp. 1178-1181 ◽

Cited By ~ 22

Author(s):

MAGDALENA NÜESCH-INDERBINEN ◽

KATHRIN ZURFLUH ◽

SOPHIE PETERHANS ◽

HERBERT HÄCHLER ◽

ROGER STEPHAN

Keyword(s):

Multidrug Resistant ◽

Wash Water ◽

Pcr Analysis ◽

Strain Identification ◽

Production Plant ◽

E Coli ◽

Extended Spectrum ◽

Large Production ◽

Fresh Cut ◽

Kluyvera Ascorbata

Ready-to-eat (RTE) prepacked salads and fruit have been successfully marketed for the last decade in Switzerland and are increasingly important as a component of everyday diets. To determine whether extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae are present in RTE salads, fresh-cut fruit, and sprouts on the Swiss market, samples of 238 mixed and unmixed RTE produce from a large production plant and 23 sprout samples from two sprout farms were analyzed. Further, four samples from the production plant's recycled wash water, which is used for crop irrigation, were analyzed. Twelve (5%) of the 238 RTE products and one of the recycled wash water samples yielded ESBL-producing Enterobacteriaceae. Strain identification and PCR analysis of the blaESBL genes revealed Kluyvera ascorbata isolated from a tomato sample harboring a blaCTX-M-2-like gene; multidrug-resistant (MDR) Enterobacter cloacae detected in a chives sample imported from Spain harboring the clinically important blaCTX-M-15 gene; and 10 Serratia spp. isolated from mixed salads (blaFONA-2 and blaFONA-2-like genes were found in 6 [60%] and blaFONA-4-like and blaFONA-5-like genes were each found in 2 [20%] of the isolates). The recycled wash water sample tested positive for one extraintestinal pathogenic MDR Escherichia coli B2:ST131 harboring blaCTX-M-27 and for one MDR E. coli A:ST88 containing blaCTX-M-3. None of the sprout samples tested positive for ESBL-producing Enterobacteriaceae. Overall, the majority of the Enterobacteriaceae detected in Swiss RTE produce were environmental strains producing minor ESBLs. The detection of an isolate producing a clinically important ESBL in a single sample and of an international circulating pathogenic strain (B2:ST131) in recycled wash water highlights the importance of surveillance of fresh produce and of recycled wash water that will be reused for irrigation purposes.

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Impact of Wash Water Quality on Sensory and Microbial Quality, Including Escherichia coli Cross-Contamination, of Fresh-Cut Escarole

Journal of Food Protection ◽

10.4315/0362-028x-71.12.2514 ◽

2008 ◽

Vol 71 (12) ◽

pp. 2514-2518 ◽

Cited By ~ 76

Author(s):

ANA ALLENDE ◽

MARIA V. SELMA ◽

FRANCISCO LÓPEZ-GÁLVEZ ◽

RAQUEL VILLAESCUSA ◽

MARÍA I. GIL

Keyword(s):

Escherichia Coli ◽

Water Quality ◽

Sensory Quality ◽

Wash Water ◽

Microbial Load ◽

Contamination Level ◽

Cross Contamination ◽

Inoculum Level ◽

E Coli ◽

Fresh Cut

The influence of wash water quality on the microbial load and sensory quality of fresh-cut escarole was evaluated. Additionally, the degree of Escherichia coli cross-contamination between inoculated and uninoculated products after washing was also studied. Three types of wash water, i.e., potable water, diluted recirculated water, and recirculated water, containing different microbial counts and organic loads, were used. Results showed that microbial load (P > 0.02) and sensory quality (P > 0.625) of the product were not influenced by the water quality after washing and storage. Cross-contamination between inoculated and uninoculated products was observed after washing, as there was significant transmission of E. coli cells from the product to the wash water (P < 0.001). When fresh-cut escarole was contaminated at a high inoculum level (5.1 log CFU/g), wash water quality influenced the level of cross-contamination, as the highest E. coli load (P < 0.001) was shown in uninoculated fresh-cut escarole washed with recirculated water. However, when fresh-cut escarole was contaminated at a low inoculum level (3.2 log CFU/g), the wash water quality did not influence the level of cross-contamination, as E. coli slightly increased, although not at a statistically significant level, after the uninoculated product was washed with recirculated water (P > 0.035). Therefore, the contamination level may impact the effectiveness of water quality to reduce pathogen concentrations. It was clearly observed that cross-contamination of fresh-cut escarole with E. coli occurs, thereby suggesting that small amounts of contamination could impact the overall product and indicating the necessity of using wash water sanitizers to eliminate pathogens.

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Tracking an Escherichia coli O157:H7–Contaminated Batch of Leafy Greens through a Pilot-Scale Fresh-Cut Processing Line

Journal of Food Protection ◽

10.4315/0362-028x.jfp-14-058 ◽

2014 ◽

Vol 77 (9) ◽

pp. 1487-1494 ◽

Cited By ~ 11

Author(s):

ANNEMARIE L. BUCHHOLZ ◽

GORDON R. DAVIDSON ◽

BRADLEY P. MARKS ◽

EWEN C. D. TODD ◽

ELLIOT T. RYSER

Keyword(s):

Escherichia Coli ◽

Membrane Filtration ◽

Fluorescent Protein ◽

Pilot Scale ◽

Escherichia Coli O157 ◽

E Coli ◽

Leafy Greens ◽

Iceberg Lettuce ◽

Processing Line ◽

Fresh Cut

Cross-contamination of fresh-cut leafy greens with residual Escherichia coli O157:H7–contaminated product during commercial processing was likely a contributing factor in several recent multistate outbreaks. Consequently, radicchio was used as a visual marker to track the spread of the contaminated product to iceberg lettuce in a pilot-scale processing line that included a commercial shredder, step conveyor, flume tank, shaker table, and centrifugal dryer. Uninoculated iceberg lettuce (45 kg) was processed, followed by 9.1 kg of radicchio (dip inoculated to contain a four-strain, green fluorescent protein–labeled nontoxigenic E. coli O157:H7 cocktail at 106 CFU/g) and 907 kg (2,000 lb) of uninoculated iceberg lettuce. After collecting the lettuce and radicchio in about 40 bags (~22.7 kg per bag) along with water and equipment surface samples, all visible shreds of radicchio were retrieved from the bags of shredded product, the equipment, and the floor. E. coli O157:H7 populations were quantified in the lettuce, water, and equipment samples by direct plating with or without prior membrane filtration on Trypticase soy agar containing 0.6% yeast extract and 100 ppm of ampicillin. Based on triplicate experiments, the weight of radicchio in the shredded lettuce averaged 614.9 g (93.6%), 6.9 g (1.3%), 5.0 g (0.8%), and 2.8 g (0.5%) for bags 1 to 10, 11 to 20, 21 to 30, and 31 to 40, respectively, with mean E. coli O157:H7 populations of 1.7, 1.2, 1.1, and 1.1 log CFU/g in radicchio-free lettuce. After processing, more radicchio remained on the conveyor (9.8 g; P < 0.05), compared with the shredder (8.3 g), flume tank (3.5 g), and shaker table (0.1 g), with similar E. coli O157:H7 populations (P > 0.05) recovered from all equipment surfaces after processing. These findings clearly demonstrate both the potential for the continuous spread of contaminated lettuce to multiple batches of product during processing and the need for improved equipment designs that minimize the buildup of residual product during processing.

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The Effect Ultrasound and Surfactants on Nanobubbles Efficacy against Listeria innocua and Escherichia coli O157:H7, in Cell Suspension and on Fresh Produce Surfaces

Foods ◽

10.3390/foods10092154 ◽

2021 ◽

Vol 10 (9) ◽

pp. 2154

Author(s):

Shamil Rafeeq ◽

Reza Ovissipour

Keyword(s):

Escherichia Coli ◽

Cell Suspension ◽

Sodium Dodecyl ◽

Listeria Innocua ◽

Wash Water ◽

Tween 20 ◽

Escherichia Coli O157 ◽

E Coli ◽

Bacterial Removal ◽

The Impact

Removing foodborne pathogens from food surfaces and inactivating them in wash water are critical steps for reducing the number of foodborne illnesses. In this study we evaluated the impact of surfactants on enhancing nanobubbles’ efficacy on Escherichia coli O157:H7, and Listeria innocua removal from spinach leaves. We evaluated the synergistic impact of nanobubbles and ultrasound on these two pathogens inactivation in the cell suspension. The results indicated that nanobubbles or ultrasound alone could not significantly reduce bacteria in cell suspension after 15 min. However, a combination of nanobubbles and ultrasonication caused more than 6 log cfu/mL reduction after 15 min, and 7 log cfu/mL reduction after 10 min of L. innocua and E. coli, respectively. Nanobubbles also enhanced bacterial removal from spinach surface in combination with ultrasonication. Nanobubbles with ultrasound removed more than 2 and 4 log cfu/cm2 of L. innocua and E. coli, respectively, while ultrasound alone caused 0.5 and 1 log cfu/cm2 of L. innocua and E. coli reduction, respectively. No reduction was observed in the solutions with PBS and nanobubbles. Adding food-grade surfactants (0.1% Sodium dodecyl sulfate-SDS, and 0.1% Tween 20), did not significantly enhance nanobubbles efficacy on bacterial removal from spinach surface.

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