scholarly journals Physicochemical Quality and Chemical Safety of Chlorine as a Reconditioning Agent and Wash Water Disinfectant for Fresh-Cut Lettuce Washing

2013 ◽  
Vol 79 (9) ◽  
pp. 2850-2861 ◽  
Author(s):  
Sam Van Haute ◽  
Imca Sampers ◽  
Kevin Holvoet ◽  
Mieke Uyttendaele
Keyword(s):  
Escherichia Coli ◽  
Water Contamination ◽  
Tap Water ◽  
Water Disinfection ◽  
Wash Water ◽  
Chemical Safety ◽  
Residual Concentration ◽  
Content Type ◽  
Washing Process ◽  
Fresh Cut

ABSTRACTChlorine was assessed as a reconditioning agent and wash water disinfectant in the fresh-cut produce industry. Artificial fresh-cut lettuce wash water, made from butterhead lettuce, was used for the experiments. In the reconditioning experiments, chlorine was added to artificial wash water inoculated withEscherichia coliO157 (6 log CFU/ml). Regression models were constructed based on the inactivation data and validated in actual wash water from leafy vegetable processing companies. The model that incorporated chlorine dose and chemical oxygen demand (COD) of the wash water accurately predicted inactivation.Listeria monocytogeneswas more resistant to chlorine reconditioning in artificial wash water thanSalmonellaspp. andEscherichia coliO157. During the washing process with inoculated lettuce (4 log CFU/g), in the absence of chlorine, there was a rapid microbial buildup in the water that accumulated to 5.4 ± 0.4 log CFU/100 ml after 1 h. When maintaining a residual concentration of 1 mg/liter free chlorine, wash water contamination was maintained below 2.7, 2.5, and 2.5 log CFU/100 ml for tap water and artificial process water with COD values of 500 and 1,000 mg O2/liter, respectively. A model was developed to predict water contamination during the dynamic washing process. Only minor amounts of total trihalomethanes were formed in the water during reconditioning. Total trihalomethanes accumulated to larger amounts in the water during the wash water disinfection experiments and reached 124.5 ± 13.4 μg/liter after 1 h of execution of the washing process in water with a COD of 1,000 mg O2/liter. However, no total trihalomethanes were found on the fresh-cut lettuce after rinsing.

Efficacy of Sodium Hypochlorite and Peroxyacetic Acid To Reduce Murine Norovirus 1, B40-8, Listeria monocytogenes, and Escherichia coli O157:H7 on Shredded Iceberg Lettuce and in Residual Wash Water

2009 ◽  
Vol 72 (5) ◽  
pp. 1047-1054 ◽  
Author(s):  
LEEN BAERT ◽  
ISABELLE VANDEKINDEREN ◽  
FRANK DEVLIEGHERE ◽  
ELS VAN COILLIE ◽  
JOHAN DEBEVERE ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Sodium Hypochlorite ◽  
Tap Water ◽  
Bacterial Pathogens ◽  
Wash Water ◽  
Escherichia Coli O157 ◽  
Murine Norovirus ◽  
Peroxyacetic Acid ◽  
Iceberg Lettuce

The efficiency of sodium hypochlorite (NaOCl) and peroxyacetic acid (PAA) to reduce murine norovirus 1 (MNV-1), a surrogate for human norovirus, and Bacteroides fragilis HSP40–infecting phage B40-8 on shredded iceberg lettuce was investigated. The levels of removal of viruses MNV-1 and B40-8 were compared with the reductions observed for bacterial pathogens Listeria monocytogenes and Escherichia coli O157:H7. Two inoculation levels, one with a high organic load and the other containing a 10-fold lower number of pathogens and organic matter, showed that the effectiveness of NaOClwas greatly influenced by the presence of organic material, which was not observed for PAA. Moreover, the present study showed that 200 mg/liter NaOCl or 250 mg/liter PAA is needed to obtain an additional reduction of 1 log (compared with tap water) of MNV-1 on shredded iceberg lettuce, whereas only 250 mg/liter PAA achieved this for bacterial pathogens. None of the treatments resulted in a supplementary 1-log PFU/g reduction of B40-8 compared with tap water. B40-8 could therefore be useful as an indicator of decontamination processes of shredded iceberg lettuce based on NaOCl or PAA. Neither MNV-1, B40-8, nor bacterial pathogens could be detected in residual wash water after shredded iceberg lettuce was treated with NaOCl and PAA, whereas considerable numbers of all these microorganisms were found in residual wash water consisting solely of tap water. This study illustrates the usefulness of PAA and NaOCl in preventing cross-contamination during the washing process rather than in causing a reduction of the number of pathogens present on lettuce.

Sensitivity analysis of Escherichia coli and Staphylococcus aureus of mixed salad vegetables during washing step at packing house

2020 ◽  
Author(s):  
Sukhuntha Osiriphun ◽  
Phichaya Poonlarp ◽  
Danai Boonyakiat ◽  
Patcharin Raviyan
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Sensitivity Analysis ◽  
Assessment Model ◽  
Health Food ◽  
E Coli ◽  
Global Trend ◽  
Washing Process ◽  
Fresh Cut ◽  
And Staphylococcus Aureus

Fresh cut vegetables are a source of minerals, vitamins, and phytonutrients that are convenient foods for consumers which are following the global trend of inclination toward health food. In terms of food safety, contamination of vegetables with microorganisms can occur at multiple points along the supply chain. This study was conducted to investigate the risk factors of Escherichia coli and Staphylococcus aureus which contaminate freshly cut vegetables during production (receiving, washing, centrifuging, and packing areas) by using a statistical method for sensitivity analysis and an exposure assessment model complying with the @RiskTM software program. At washing step, the numbers of S. aureus found in the vegetables and water were 0.79 ±1.76 Log cfu/g and 0.68±1.52 Log cfu, respectively. For the equipment, the hand, and the table swabbing samples, the numbers of S. aureus were 0.48±1.07 Log cfu/25 cm2, 1.81±1.69 Log cfu/25 cm2 , and 0.54±1.21 Log cfu/25 cm2 , respectively. An amount of E. coli of 0.48±1.07 Log cfu/25 cm2 was found in the table swabbing samples at the packing area. E.coli and S. aureus were not found in any of the mixed fresh-cut salad samples; therefore, the product samples could be considered safe for consumers. The result of the sensitivity analysis showed that the temperature and pH of water samples were the important factors in the washing process. The suggested interventions included monitoring and maintaining the water temperature at 5°C; also, maintaining the pH of water between 6.5 and 7.5 could help to reduce pathogen contamination of freshly cut vegetables.

Determination of Free Chlorine Concentrations Needed To Prevent Escherichia coli O157:H7 Cross-Contamination during Fresh-Cut Produce Wash†

2011 ◽  
Vol 74 (3) ◽  
pp. 352-358 ◽  
Author(s):  
YAGUANG LUO ◽  
XIANGWU NOU ◽  
YANG YANG ◽  
ISABEL ALEGRE ◽  
ELLEN TURNER ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Free Chlorine ◽  
Chlorine Concentration ◽  
Wash Water ◽  
Escherichia Coli O157 ◽  
Cross Contamination ◽  
E Coli ◽  
Wash Solution ◽  
Fresh Cut ◽  
Experimental Trials

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.

scholarly journals Silica Gel for Enhanced Activity and Hypochlorite Protection of Cyanuric Acid Hydrolase in Recombinant Escherichia coli

mBio ◽  
2015 ◽  
Vol 6 (6) ◽  
Author(s):  
Adi Radian ◽  
Kelly G. Aukema ◽  
Alptekin Aksan ◽  
Lawrence P. Wackett
Keyword(s):  
Escherichia Coli ◽  
Cyanuric Acid ◽  
Uv Spectroscopy ◽  
Water Disinfection ◽  
Enzyme Inactivation ◽  
Amine Group ◽  
Acid Hydrolase ◽  
Whole Cell ◽  
Content Type ◽  
Degradation Rates

ABSTRACTChlorinated isocyanuric acids are widely used water disinfectants that generate hypochlorite, but with repeated application, they build up cyanuric acid (CYA) that must be removed to maintain disinfection. 3-Aminopropyltriethoxysilane (APTES)-treatedEscherichia colicells expressing cyanuric acid hydrolase (CAH) fromMoorella thermoaceticaexhibited significantly high CYA degradation rates and provided protection against enzyme inactivation by hypochlorite (chlorine). APTES coating or encapsulation of cells had two benefits: (i) overcoming diffusion limitations imposed by the cell wall and (ii) protecting against hypochlorite inactivation of CAH activity. Cells encapsulated in APTES gels degraded CYA three times faster than nonfunctionalized tetraethoxysilane (TEOS) gels, and cells coated with APTES degraded CYA at a rate of 29 µmol/min per mg of CAH protein, similar to the rate with purified enzyme. UV spectroscopy, fluorescence spectroscopy, and scanning electron microscopy showed that the higher rates were due to APTES increasing membrane permeability and enhancing cyanuric acid diffusion into the cytoplasm to reach the CAH enzyme. Purified CAH enzyme was shown to be rapidly inactivated by hypochlorite. APTES aggregates surrounding cells protected via the amine groups reacting with hypochlorite as shown by pH changes, zeta potential measurements, and infrared spectroscopy. APTES-encapsulatedE. colicells expressing CAH degraded cyanuric acid at high rates in the presence of 1 to 10 ppm hypochlorite, showing effectiveness under swimming pool conditions. In contrast, CAH activity in TEOS gels or free cells was completely inactivated by hypochlorite. These studies show that commercially available silica materials can selectively enhance, protect, and immobilize whole-cell biocatalysts for specialized applications.IMPORTANCEHypochlorite is used in vast quantities for water disinfection, killing bacteria on surfaces, and washing and whitening. In pools, spas, and other waters, hypochlorite is frequently delivered as chlorinated isocyanuric acids that release hypochlorite and cyanuric acid. Over time, cyanuric acid accumulates and impairs disinfection and must be removed. The microbial enzyme cyanuric acid hydrolase can potentially remove cyanuric acid to restore disinfection and protect swimmers. Whole bacterial cells expressing cyanuric acid hydrolase were encapsulated in an inert silica matrix containing an amine group. The amine group serves to permeabilize the cell membrane and accelerate cyanuric acid degradation, and it also reacts with hypochlorite to protect against inactivation of cyanuric acid hydrolase. Methods for promoting whole-cell biocatalysis are important in biotechnology, and the present work illustrates approaches to enhance rates and protect against an inhibitory substance.

Behavior of Shiga Toxigenic Escherichia coli Relevant to Lettuce Washing Processes and Consideration of Factors for Evaluating Washing Process Surrogates

2014 ◽  
Vol 77 (11) ◽  
pp. 1860-1867 ◽  
Author(s):  
KAIPING DENG ◽  
XUE WANG ◽  
LI-HAN YEN ◽  
HONGLIU DING ◽  
MARY LOU TORTORELLO
Keyword(s):  
Escherichia Coli ◽  
Bacterial Species ◽  
Wash Water ◽  
Lag Phase ◽  
Phenotypic Traits ◽  
Cross Contamination ◽  
Process Validation ◽  
E Coli ◽  
Hazard Characterization ◽  
Washing Process

Postharvest processes for fresh produce commonly include washing in water containing antimicrobial chemicals, such as chlorine; however, if the antimicrobials are not present in sufficient levels, washing can promote the spread of contamination that might be present. To understand cross-contamination risk during washing, we tested a collection of Shiga toxigenic Escherichia coli (STEC), including O157:H7 and other non-O157 strains, for certain traits during washing of fresh-cut lettuce, i.e., sensitivity to sublethal chlorine levels and ability to cross-contaminate (detach from and attach to) lettuce in the presence of sublethal chlorine levels. Nonpathogenic E. coli Nissle 1917 (EcN) and Pediococcus pentosaceus lactic acid bacterial species (LAB) were included as potential washing process validation surrogates. As measured by extension of the lag phase of growth in media containing 0.15 ppm of chlorine, chlorine sensitivity varied among the STECs. Cross-contamination was assessed by evaluating transfer of bacteria from inoculated to uninoculated leaves during washing. Without chlorine, similar transfer to wash water and uninoculated leaves was shown. In 1 ppm of chlorine, cross-contamination was not detected with most strains, except for the substantial transfer by a STEC O111 strain and EcN in some replicates. Strain O111 and EcN showed less inactivation in 0.25 ppm of chlorine water compared with O157 (P < 0.05). LAB showed similar transfer and similar chlorine inactivation to O157. Considering together the sublethal chlorine sensitivity and detachment/attachment traits, neither EcN nor LAB displayed optimal characteristics as washing process surrogates for the STEC strains, although further evaluation is needed. This work demonstrated a range of behaviors of STEC strains during lettuce washing and may be helpful in hazard characterization, identifying factors to consider for evaluating washing process efficacy, and identifying phenotypic traits to select surrogates to validate washing processes.

Fresh-cut product sanitation and wash water disinfection: Problems and solutions

2009 ◽  
Vol 134 (1-2) ◽  
pp. 37-45 ◽  
Author(s):  
Maria I. Gil ◽  
Maria V. Selma ◽  
Francisco López-Gálvez ◽  
Ana Allende
Keyword(s):  
Water Disinfection ◽  
Wash Water ◽  
Problems And Solutions ◽  
Fresh Cut

Effects of natural antimicrobials on prevention and reduction of bacterial cross-contamination during the washing of ready-to-eat fresh-cut lettuce

2017 ◽  
Vol 23 (5) ◽  
pp. 403-414 ◽  
Author(s):  
Cristina Pablos ◽  
Alba Fernández ◽  
Alison Thackeray ◽  
Javier Marugán
Keyword(s):  
Antimicrobial Properties ◽  
Complete Removal ◽  
Wash Water ◽  
Plate Count ◽  
Salmonella Spp ◽  
Natural Antimicrobials ◽  
Benzyl Isothiocyanate ◽  
Standard Plate Count ◽  
Washing Process ◽  
Fresh Cut

Microbiological safety of the fresh-cut produce may not be guaranteed if the quality of wash water is not maintained. The use of natural antimicrobials as alternative to chlorine may offer interesting possibilities for disinfecting wash water. Antimicrobial properties of allyl- and benzyl-isothiocyanates, respectively, and chitosan against Salmonella spp. were evaluated by standard plate count. Minimal inhibitory concentration values were observed for benzyl-isothiocyanate and chitosan, corresponding to 50 and 1000 mgl−1, respectively. A 5 min washing of 25 g fresh-cut lettuce was performed. Transfer of Salmonella from the water to the produce was observed. Benzyl-isothiocyanate addition of 75 mgl−1 before starting the washing process gave rise to a complete removal of total bacteria and Salmonella in the wash water after 24 h before starting the second cycle. Antimicrobial benzyl-isothiocyanate effects have been demonstrated to persist after 48 h.

Efficacy of Sanitizers To Inactivate Escherichia coli O157:H7 on Fresh-Cut Carrot Shreds under Simulated Process Water Conditions†

2004 ◽  
Vol 67 (11) ◽  
pp. 2375-2380 ◽  
Author(s):  
ROLANDO J. GONZALEZ ◽  
YAGUANG LUO ◽  
SAUL RUIZ-CRUZ ◽  
JAMES L. McEVOY
Keyword(s):  
Escherichia Coli ◽  
Tap Water ◽  
Process Water ◽  
Sodium Chlorite ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Water Conditions ◽  
Processing Water ◽  
Fresh Cut ◽  
Pathogen Reduction

Chlorine is widely used as a sanitizer to maintain the microbial quality and safety of fresh-cut produce; however, chlorine treatment lacks efficacy on pathogen reduction, especially when the fresh-cut processing water contains heavy organic loads. A more efficacious sanitizer that can tolerate the commercial processing conditions is needed to maintain microbial safety of fresh-cut produce. This study evaluated the efficacy of Escherichia coli O157:H7 reduction on fresh-cut carrots using new and traditional sanitizers with tap water and fresh-cut processing water scenarios. Fresh-cut carrot shreds inoculated with E. coli O157:H7 were washed in sanitizer solutions including 200 ppm chlorine, citric acid–based sanitizer (Pro-San), 80 ppm peroxyacetic acid-based sanitizer (Tsunami 100), and 1,000 ppm acidified sodium chlorite (SANOVA) prepared in fresh tap water or simulated processing water with a chemical oxygen demand level of approximately 3,500 mg/liter. Samples were packaged and stored at 5°C. Microbial analyses performed at days 0, 7, and 14 indicate that the organic load in the process water significantly affected the efficacy of chlorine on pathogen removal and was especially evident on samples tested during storage. Acidified sodium chlorite provided a strong pathogen reduction even under process water conditions with up to a 5.25-log reduction when compared with the no-wash control. E. coli O157:H7 was not recovered on acidified sodium chlorite–treated samples during the entire 14 days of storage, even following an enrichment step. These results suggest that acidified sodium chlorite holds considerable promise as an alternative sanitizer of fresh-cut produce.

Electrochemical Drinking Water Disinfection with TiO2-x Ceramic Electrodes at Flow Conditions

2016 ◽  
Vol 721 ◽  
pp. 133-137
Author(s):  
Viktorija Denisova ◽  
Linda Mezule ◽  
Tālis Juhna ◽  
Jurijs Ozolins
Keyword(s):  
Escherichia Coli ◽  
Drinking Water ◽  
Titanium Oxide ◽  
Laboratory Experiments ◽  
Tap Water ◽  
Water Disinfection ◽  
Flow Conditions ◽  
System Parameters ◽  
Ceramic Electrodes ◽  
Drinking Water Disinfection

Electrochemical disinfection device EDI-001 equipped with titanium oxide (TiO2-x) ceramic electrodes was tested as a system for direct treatment of drinking water at flow conditions. Laboratory experiments were conducted to estimate the disinfection efficiency and main system parameters. Escherichia coli was selected as the model microorganism. The results have shown that contaminated tap water was completely disinfected within 15 minutes by using EDI-001.

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