Source: https://www.ecoloxtech.com/research-microbe-display?type=Bacteria&microbe=Escherichia%20coli
Timestamp: 2019-04-19 04:58:20+00:00

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The sanitising effect of low concentration neutralised electrolysed water (LCNEW, pH: 7.0, free available chlorine (FAC): 4 mg/L) combined with ultrasound (37 kHz, 80 W) on food contact surface was evaluated. Stainless steel coupon was chosen as attachment surface for Escherichia coli ATCC 25922, Pichia pastoris GS115 and Aureobasidium pullulans 2012, representing bacteria, yeast and mold, respectively. The results showed that although LCNEW itself could effectively reduce survival population of E. coli ATCC 25922, P. pastoris GS115 and low concentration A. pullulans 2012 in planktonic status, LCNEW combined with ultrasound showed more sanitising efficacy for air-dried cells on coupons, with swift ificantly reduced the survival cells both on coupons and in suspension for all three strains. The results suggest that LCNEW combined with ultrasound is a promising approach to sanitise food equipment.
Electrolysed oxidising water (E.O. water) is produced by electrolysis of sodium chloride to yield primarily chlorine based oxidising products. At neutral pH this results in hypochlorous acid in the un-protonated form which has the greatest oxidising potential and ability to penetrate microbial cell walls to disrupt the cell membranes. E.O. water has been shown to be an effective method to reduce microbial contamination on food processing surfaces. The efficacy of E.O. water against pathogenic bacteria such as Listeria monocytogenes, Escherichia coli and Vibrio parahaemolyticus has also been extensively confirmed in growth studies of bacteria in culture where the sanitising agent can have direct contact with the bacteria. However it can only lower, but not eliminate, bacteria on processed seafoods. More research is required to understand and optimise the impacts of E.O. pre-treatment sanitation processes on subsequent microbial growth, shelf life, sensory and safety outcomes for packaged seafood products.
The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hyrol possible unhygienic practices during production and processing of shellfish without apparent changes in the quality of the shellfish.
Chemotherapeutic agents have been used as an adjunct to mechanical debridement for peri-implantitis treatment. The present in vitro study evaluated and compared the effectiveness of hypochlorous acid (HOCl), sodium hypochlorite (NaOCl), and chlorhexidine (CHX) at eliminating Gram-negative (E. coli and P. gingivalis) and Gram-positive (E. faecalis and S. sanguinis) bacteria. The effect of irrigating volume and exposure time on the antimicrobial efficacy of HOCl was evaluated, and a durability analysis was completed. Live/dead staining, morphology observation, alamarBlue assay, and lipopolysacLPS) detection were examined on grit-blasted and biofilm-contaminated titanium alloy discs after treatment with the three chemotherapeutic agents. The results indicated that HOCl exhibited better antibacterial efficacy with increasing irrigating volumes. HOCl achieved greater antibacterial efficacy as treatment time was increased. A decrease in antimicrobial effectiveness was observed when HOCl was unsealed and left in contact with the air. All the irrigants showed antibacterial activity and killed the majority of bacteria on the titanium alloy surfaces of biofilm-contaminated implants. Moreover, HOCl significantly lowered the LPS concentration of P. gingivalis when compared with NaOCl and CHX. Thus, a HOCl antiseptic may be effective for cleaning biofilm-contaminated implant surfaces.
The capacity of slightly acidic hypochlorous acid water (SAHW), in both liquid and spray form, to inactivate bacteria was evaluated as a potential candidate for biosecurity enhancement in poultry production. SAHW (containing 50 or 100 ppm chlorine, pH 6) was able to inactivate Escherichia coli and Salmonella Infantis in liquid to below detectable levels (2.6 log10 CFU/ml) within 5 sec of exposure. In addition, SAHW antibacterial capacity was evaluated by spraying it using a nebulizer into a box containing these bacteria, which were present on the surfaces of glass plates and rayon sheets. SAHW was able to inactivate both bacterial species on the glass plates (dry condition) and rayon sheets within 5 min spraying and 5 min contact times, with the exception of 50 ppm SAHW on the rayon sheets. Furthermore, a corrosivity test determined that SAHW does not corrode metallic objects, even at the longest exposure times (83 days). Our findings demonstrate that SAHW is a good candidate for biosecurity enhancement in the poultry industry. Spraying it on the surfaces of objects, eggshells, egg incubators and transport cages could reduce the chances of contamination and disease transmission. These results augment previous findings demonstrating the competence of SAHW as an anti-viral disinfectant.
In the present study, the disinfection efficacy on fresh-cut cilantro of the combination of strongly acidic electrolyzed water (AcEW) and alkaline electrolyzed water (AlEW) was evaluated, in comparison with single slightly acidic electrolyzed water (SAEW) and single AcEW treatments. The populations of E. Coli O78 on inoculated cilantro treated by AlEW 5 min + AcEW 5 min, was not detected while 3.43 and 3.73 log10 CFU/g in the AlEW 2.5 min + AcEW 2.5 min and AcEW 2 min + AlEW 2 min + AcEW 2 min treatments respectively. Our results implied that the bactericidal abilities of the combination of AlEW and AcEW treatments were higher than that of single AcEW and SAEW, which also was demonstrated microscopically by scanning electron microscopy (SEM). Moreover, the efficacy of combination of AcEW and AlEW in reducing natural micro flora on fresh-cut cilantro was also evaluated compared with single AcEW and SAEW. The results showed that the combination of AlEW and AcEW had stronger sterilization ability than single AcEW and SAEW. Considering the utilizations of AlEW and disinfection efficacy, we suggest that the combination of AlEW and AcEW may also be a better choice in fresh-cut produce.
The objective of this study was to evaluate the effectiveness of slightly acidic electrolyzed water (SAEW) in reducing pathogens on pure cultures and on cotton fabric surfaces in the presence of organic matter and estimate its efficacy in comparison with povidone iodine solution for reducing pathogenic microorganisms on internal surfaces of layer houses. Pure cultures of E.coli, S.enteritidis, and S.aureus and cotton fabric surfaces inoculated with these strains were treated with SAEW in the presence of bovine serum albumin (BSA). In the absence of BSA, complete inactivation of all strains in pure cultures and on cotton fabric surfaces was observed after 2.5 and 5 min treatment with SAEW at 40 mg/L of available chlorine concentration (ACC), respectively. The bactericidal efciency of SAEW increased with increasing ACC, but decreased with increasing BSA concentration. Then, the surfaces of the layer houses were sprayed with SAEW at 60, 80, and 100 mg/L of ACC and povidone iodine using the automated disinfection system at a rate of 110 mL/m2, respectively. Samples from the floor, wall, feed trough, and egg conveyor belt surfaces were collected with sterile cotton swabs before and after spraying disinfection. Compared to tap water, SAEW and povidone iodine significantly reduced microbial populations on each surface of the layer houses. SAEW with 80 or 100 mg/L of ACC showed significantly higher efficacy than povidone iodine for total aerobic bacteria, staphylococci, coliforms, or yeasts and moulds on the floor and feed trough surfaces (P < 0.05). SAEW was more effective than povidone iodine at reducing total aerobic bacteria, coliforms, and yeasts and moulds on the wall surface. Additionally, SAEW had similar bactericidal activity with povidone iodine on the surface of the egg conveyor belt. Results suggest that SAEW exerts a higher or equivalent bactericidal efficiency for the surfaces compared to povidone iodine, and it may be used as an effective alternative for reducing microbial contamination on surfaces in layer houses.
The aim of this study was to determine the combined effects of slightly acidic electrolyzed water SAEW (pH range 5.06.5, oxidationreduction potential 6501000 mV, available chlorine concentration 1080 mg/L) containing 0, 15, and 30 ppm chlorine and 0, 50, and 100 min of ultrasound US (37 kHz, 380 W) using the central composite design (CCD) on the reductions of Escherichia coli and Vibrio parahaemolyticus (initial value, approximately 67 log10 colony forming unit (CFU) of E. coli or V. parahaemolyticus/g) and the sensory properties on freshly sliced shad (Konosirus punctatus), in comparison with SAEW or US alone. Another aim was to develop the response surface model for E. coli and V. parahaemolyticus in the shad treated with the combination of SAEW and US. Single treatments with SAEW (chlorine 15 ppm), SAEW (chlorine 30 ppm), or US for 50 min caused a much-less-than-1-log10 reduction in the number of both E. coli and V. parahaemolyticus in the shad. In contrast, the combination of SAEW (15 or 30 ppm chlorine) and US (50 or 100 min) caused >1-log10 reduction of E. coli numbers (1.041.86 log reduction) and V. parahaemolyticus (1.021.42 log reduction) in the shad. In addition, the sensory properties of the shad were not changed under the harshest conditions of the combination (SAEW with chlorine at 30 ppm and US for 100 min). Response surface models were developed for the population of E. coli (Y=6.153220.024732X 10.016486X 20.00015X 1 X 20.00024X 1 20.00007X 2 2) and V. parahaemolyticus (Y=5.676490.042598X 10.014013X 20.00003X 1 X 20.00006X 1 20.00062X 2 2 ), where Y is the bacterial population (log10 CFU), X 1 is ppm chlorine in SAEW, and X 2 is the duration of treatment (min) with US. The appropriateness of the models was verified by bias factor (B f 1.10 for E. coli, 1.03 for V. parahaemolyticus), accuracy factor (A f 1.11 for E. coli, 1.05 for V. parahaemolyticus), mean square error (MSE 0.0087 for E. coli, 0.0028 for V. parahaemolyticus), and coefficient of determination (R 2 0.976 for E. coli, 0.982 for V. parahaemolyticus). To produce a 1-log10 reduction of E. coli and V. parahaemolyticus, US treatment times for E. coli and V. parahaemolyticus were calculated within the maximum of 54 and 67 min, respectively, at chlorine 10 ppm in SAEW. SAEW chlorine concentrations (ppm) for E. coli and V. parahaemolyticus were calculated within the maximum of 38 and 41 ppm, respectively, at 20 min of US. Therefore, the resulting response surface models for E. coli and V. parahaemolyticus should be further validated on slices of other kinds of raw fish. Ultimately, the response surface quadratic polynomial equations may thus be used for predicting the combined treatments of SAEW and against E. coli and V. parahaemolyticus in raw fish production, processing, and distribution.
Physicochemical and antibacterial properties of carrageenan and gelatine hydrosols and hydrogels incorporated with acidic electrolyzed water.
The article focuses on investigation of the effects of usage of acidic electrolyzed water (AEW) with different sodium chloride concentration (0.001, 0.01, and 0.1) for the preparation of carrageenan and gelatine hydrosols and hydrogels. To determine physiochemical properties of hydrosols, the pH, oxidation-reduction potential (ORP), available chloride concentration (ACC) and rheological parameters such us gelation and flow temperatures were measured. The samples were also 0.1 w/v). These results suggest that hydrogels and hydrosols incorporated with AEW may be used for food preservation.
This study investigated the effect of electrolyzed water on pathogenic bacteria cell suspensions. Specifically, we evaluated the efficacy of strong and weak acidic electrolyzed waters (SACEW, WACEW) and strong and weak alkaline electrolyzed waters (SALEW, WALEW) on Vibrio parahaemolyticus, Listeria monocytogenes, Aeromonas hyificantly more resistant to ALEW compared to ACEW. Results also show that the bactericidal activity of SACEW (20 mg/mL ACC) was more effective than WACEW (10 mg/mL ACC) in terms of inactivating E. coli O104:H4. Alkaline-electrolyzed waters were found to reduce cell numbers by 13 log (P < 0.05). However, alkaline electrolyzed water was less effective (P < 0.05) than acidic electrolyzed treatment.
Application of slightly acidic electrolyzed water (SAEW) in combination with ultrasound for decontamination of kashk was investigated. SAEW had a pH of 5.3-5.5, an oxidation reduction potential of 545-600 mV, and an available chlorine concentration of 20-22 mg/L. Kashk is a dairy product with a unique aroma and a high nutritive value produced in Iran. A 2/1 SAEW/kashk ratio showed 1.42, 1.13, 1.24, and 1.37 log CFU/mL microbial reductions in Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Aspergillus fumigatus, respectively, at room temperature. A combination of SAEW treatment with ultrasound (SAEWultrasound) resulted in 1.87, 1.67, 1.71, and 1.91 log CFU/mL reductions in S. aureus, B. cereus, E. coli, and A. fumigatus, respectively. The developed hurdle approach can be a useful tool for sanitization of kashk and similar products. Application of SAEWultrasound in dairy microbial decontamination is first reported herein.
Pathogenic contamination is a food safety concern. This study was conducted to investigate the efficacy of neutral electrolyzed water (NEW) in killing pathogens, namely, Vibrio parahaemolyticus, Vibrio vulnificus, Salmonella Enteritidis, and Escherichia coli in shrimp. Pure cultures of each pathogen were submerged separately in NEW containing five different chlorine concentrations: 10, 30, 50, 70, and 100 ppm. For each concentration, three submersion times were tested: 1, 3, and 5 min. The population of V. parahaemolyticus was rapidly reduced even at low concentrations, but prolonged contact times caused only a slight reduction. V. vulnificus was gradually inhibited with increasing NEW concentrations and contact times. For the V. parahaemolyticus applications of 70 ppm for 5 min and of 100 ppm for 3 min, each eliminated 7 log CFU/ml. For V. vulnificus, applications of 50 ppm for 3 min and 100 ppm for 1 min, each eliminated 7 log CFU/ml. Salmonella Enteritidis and E. coli were slightly reduced by NEW. Applications of 50 ppm for 15 min and 10 ppm for 30 min completely eliminated 4.16 log CFU/g of V. parahaemolyticus in inoculated shrimp, while only a 1-log CFU/g reduction of V. vulnificus was detected. Soaking shrimp in 10 ppm NEW for 30 min did not affect its sensory quality. Our results suggest NEW could be an alternative sanitizer to improve the microbiological quality of seafood.
In the wake of discussion about the of drugs in food-producing farms, it seems to be more and more important to search for ncy of treatment days was represented by the number of used daily doses per population and showed lower values in EO-water-treated groups at both farms. Furthermore, the addition of EO water resulted in a lower mortality rate. In terms of analyzed performance parameters, no significant differences were determined. In this study, the of EO water improved drinking water quality and seemed to reduce the drug without showing negative effects on performance parameters and mortality rates.
To evaluate the disinfection effectiveness of slightly acidic electrolysed water (SAEW, pH 625653), a new environmental friendly agent for inactivating micro-organisms adhered to the facility and aerosolized in the air of the swine barns and to explore the application of SAEW in livestock industries. Methods and Results Bacteria and fungi were isolated from the swine hoair and treated by SAEW. The SAEW solution was flushed onto surfaces and sprayed within the whole swine barn. SAEW with an available chlorine concentration (ACC) of 300 mg l1 can inhibit isolated microbes completely. The usage of SAEW (300 mg l1) resulted in a significant (P < 005) reduction in microbes on the wall, rail and floor after flushing disinfection. Additionally, spraying SAEW at an ACC of 300 mg l1 reduced 59 of the airborne organisms in 30 min and kept the population of microbes at a reduced level for at least 8 h. SAEW treatment also reduced pathogens on surfaces (P < 003) after spraying disinfection except on the surface of the wall. Conclusions SAEW may be a potential alternative disinfectant to reduce infections in swine barns Significance and Impact of the Study The results of this study provide information on the antimicrobial efficiency of SAEW on the airborne bacteria and fungi in swine barns.
Salmonella spp. may be found in the nest box of breeder chickens, cold egg-storage rooms at the farm, on the hatchery truck, or in the hatchery environment (5). These bacteria may then be spread to fertilized hatching eggs on the shell or, in some cases, may penetrate the shell and reside just beneath the surface of the eggshell.Research has demonstrated that contamination of raw poultry products with Salmonella spp. may be attributable to cross-contamination in the hatchery from Salmonella infected eggs or surfaces to uninfected baby chicks during the hatching process. Cox et al. (6 and 7) reported that broiler and breeder hatcheries were highly contaminated with Salmonella spp. Within the broiler hatchery, 71 percent of eggshell fragments, 80 percent of chick conveyor belts swabs, and 74 percent of pad samples placed under newly hatched chicks contained Salmonella spp. (6).Cason et al. (4) reported that, although fertile hatching eggs were contaminated with high levels of Salmonella typhimurium, they were still able to hatch. The authors stated that paratyphoid salmonellae do not caadverse health affects to the developing and hatching chick. During the hatching process, Salmonella spp. is readily spread throughout the hatching cabinet due to rapid air movement by circulation fans. When eggs were inoculated with a marker strain of Salmonella during hatching, greater than 80 percent of the chicks in the trays above and below the inoculated eggs were contaminated (4). In an earlier study, Cason et al. (3) demonstrated that salmonellae on the exterior of eggs or in eggshell membranes could be transmitted to baby chicks during pipping.Salmonella may persist in hatchery environments for long periods of time. When chick fluff contaminated with Salmonella was held for 4 years at room temperature, up to 1,000,000 Salmonella cells per gram could be recovered from these samples (12).Researchers have demonstrated a link between cross-contamination in the hatchery and contaminated carcasses during processing. Goren et al. (8) isolated salmonellae from three different commercial hatcheries in Europe and reported that the same serotypes found in the hatcheries could be found on processed broiler chicken carcass skin. Proper disinfection of the hatchery environment and fertile hatching eggs, therefore, is essential for reducing Salmonella on ready-to-cook carcasses.
The food industry has recognized electrolyzed oxidizing water (EOW) as a promising alternative decontamination technique. However, there is not a consensus about the sanitizing mechanism of EOW. In this study, we evaluated the disinfection efficacy of different types of EOW on Escherichia coli. Based on the hypothesis of hydroxyl radicals existing in EOW, in the present study, the hydroxyl radicals existed in slightly acidic electrolyzed water (SAEW) and acidic electrolyzed water (AEW) diluted to different levels were detected quantitatively. An ultraviolet (UV) spectrophotometer was used to scan EOW with different pH values. Accounting for the results of UV scanning to EOW with different pH value and the disinfection efficacy of different types of EOW, it can be concluded that considering the lower chlorine concentration of EOW compared with traditional chlorine disinfectants, the existing form of chlorine compounds rather than the hydroxyl radicals played important role in the disinfection efficacy of EOW.
The effects of various sanitizers on the viability and cellular injury to structures of Escherichia coli and Listeria innocua were investigated. A food grade organic acidic formulation (pH 2.5) and acidic, neutral, and basic electrolyzed water [AEW (pH 2.7, oxidation reduction potential; ORP: 1100 mV, free available chlorine; FAC: 150 ppm), NEW (pH 6.9, ORP: 840 mV, FAC: 150 ppm), BEW (pH 11.6, ORP: 810 mV)] were used to treat E. coli and L. innocua cells. After 10 min of exposure to the sanitizers, changes to the bacterial numbers and cell structures were evaluated by plate counting and transmission electron microscopy (TEM), respectively. It was concluded from the results that the sanitizers reduced the E. coli cells between 2 and 3 log CFU/mL. Except for the BEW treatment, reductions in L. innocua population were greater (>1 log CFU/mL) than that of E. coli for all treatments. Data from the TEM showed that all sanitizers caused changes to the cell envelope and cytoplasm of both organisms. However, smaller changes were observed for L. innocua cells. Decrease in the integrity of the cell envelope and aggregation of the cytoplasmic components appeared to be mainly because of exposure to the sanitizers. The organic acid formulation and AEW were the most effective sanitizers against bacterial cells, indicating that penetration of acidic substances effectively caused the cell inactivation.
The effectiveness of neutral electrolyzed water (NEW) to sanitize cutting boards used for food preparation was investigated. Cutting boards made of hardwood and bamboo were inoculated with Escherichia coli K12 and Listeria innocua, dried for 1 h, washed, rinsed and sanitized with NEW, sodium hypochlorite (NaClO) solution, or tap water (control). After each washing protocol, surviving bacterial populations were determined. Results showed that both NEW and NaClO sanitizing solutions produced similar levels of bacterial reductions. In manual washing, the population reductions by NEW and NaClO were 3.4 and 3.6 log10 CFU/100 cm2 for E. coli, and 4.1 and 3.9 log10 CFU/100 cm2 for L. innocua, respectively. In the automatic washing, the reductions by NEW and NaClO were 4.0 and 4.0 log10 CFU/100 cm2 for E. coli, and 4.2 and 3.6 log10 CFU/100 cm2 for L. innocua, respectively. No significant differences (P > 0.05) were observed in surviving bacteria counts when comparing board material types.
Electrolyzed seawater (ESW) is reportedly an effective disinfectant for aquaculture equipment becaof its simple mechanism and cost effectiveness. The potential of electrolyzed seawater for oyster depuration was studied using different experiments. The first was determination of chlorine tolerance of oysters. Second was effectiveness of ESW against Escherichia coli in artificially contaminated oysters and third was effectiveness of ESW against E. coli in naturally contaminated oysters from two culture farms. Tolerance of oysters for Chlorine was studied by scanning electron microscopy (SEM) and histological observation demonstrating that more than 0.5 mg/L of chlorine was toxic while 0.2 mg/L was safe for the oysters. Oysters artificially contaminated with E. coli (230 MPN/100 mL, 16.5 C for 15 h) were depurated for 6, 24, and 48 h using ESW and UV irradiated seawater. E. coli counts in artificially contaminated oysters decreased to below the detection limit (30 E. coli MPN/100 g) after depuration with ESW for 24 h or UV irradiated seawater for 6 h. In experiments on naturally contaminated oysters E. coli counts decreased to below detection limits after depuration with ESW for 24 h. From these results, electrolysis of seawater is a useful method for post harvest elimination of E. coli from oysters.
The efficacy of slightly acidic electrolyzed water (SAEW) for reducing microbial contamination on fresh-cut cilantro was investigated in this study. The impacts of SAEW on the microbes of cilantro samples inoculated with two kinds of bacteria (Escherichia coli O78 and Bacillus subtilis 1.1849) were evaluated in comparison with NaClO solution and acidic electrolyzed water (AEW). Dipping with AEW, SAEW and NaClO solutions for 5 min resulted in a reduction in populations of E. coli O78 from 6.38 to 4.93, 3.89 and 4.88 log10 cfu/g and in populations of B. subtilis from 6.52 to 5.02, 4.98, 4.63 log10 cfu/g, respectively, The similar results were found that the populations on cilantro inoculated the mixture of two microbes of E. coli O78 treated with AEW, SAEW and NaClO solutions decreased to 4.15, 3.99, 5.10 log10 cfu/g, respectively, and the populations of B. subtili on cilantro decreased to 5.08,4.97,4.82 log10 cfu/g, respectively. The efficacies of SAEW wash in reducing natural micro flora on fresh-cut cilantro were studied. The results showed SAEW had strong disinfection ability to reduce the microbe population of fresh-cut cilantro and could be an alternative of AEW and NaClO solutions.
The objective of this study was to evaluate the efficacy of slightly acidic electrolyzed (SAEO) water in killing or removing Escherichia coli O157:H7 on iceberg lettuce and tomatoes by washing and chilling treatment simulating protocols used in food service kitchens. Whole lettuce leaves and tomatoes were spot-inoculated with 100 L of a mixture of 5 strains of E. coli O157:H7. Washing lettuce with SAEO water for 15 s reduced the pathogen by 1.4 to 1.6 log CFU/leaf, but the treatments did not completely inactivate the pathogen in the wash solution. Increasing the washing time to 30 s increased the reductions to 1.7 to 2.3 log CFU/leaf. Sequential washing in SAEO water for 15 s and then chilling in SAEO water for 15 min also increased the reductions to 2.0 to 2.4 log CFU/leaf, and no cell survived in chilling solution after treatment. Washing tomatoes with SAEO water for 8 s reduced E. coli O157:H7 by 5.4 to 6.3 log CFU/tomato. The reductions were increased to 6.6 to 7.6 log CFU/tomato by increasing the washing time to 15 s. Results suggested that application of SAEO water to wash and chill lettuce and tomatoes in food service kitchens could minimize cross-contamination and reduce the risk of E. coli O157:H7 present on the produce.
Chlorine (sodium hypochlorite solution) is the most common disinfectant used in the fresh-cut industry, however, environmental and health risks related to its use have resulted in a need to find new sanitizers. Electrolyzed water (EW) is a promising alternative, showing a broad spectrum of microbial decontamination. In this study the efficacy of acidic electrolyzed water (AEW) and neutral electrolyzed water (NEW) as disinfectants of apple slices inoculated with Escherichia coli, Listeria innocua or Salmonella choleraesuis, individually or in a mixture, were compared to that of sodium hypochlorite solution and distilled water. Apple slices were inoculated with a 107 cfu/mL suspension of the pathogens and treated with diluted electrolyzed water. Bactericidal activity of washing treatments was assessed after 30 min and after storage for 5 days at 4 C. AEW and NEW disinfection efficacy was compared to that of washings with sodium hypochlorite at the same free chlorine concentration and with distilled water. AEW diluted to 100 mg/L of free chlorine was the treatment with the highest bactericidal activity in all tested conditions (reductions obtained ranged from 1.2 to 2.4 log units) followed by NEW and AEW at 100 and 50 mg/L of free chlorine respectively. In general these treatments were equal or more effective than sodium hypochlorite washings at 100 mg/L of free chlorine. The effect of the different sanitizer washings when pathogens where in a mixture was similar to that which occurred when pathogens were individually inoculated. The effectiveness of all washings slightly decreased when apple slices were stored for 5 days at 4 C.
Microbe(s): Escherichia coli, Salmonella spp.
The sanitization efficacy of slightly acidic electrolyzed water (SAEW) against food pathogens on selected fresh ready-to-eat (RTE) vegetables and sprouts was evaluated and compared to sodium hypochlorite (NaOCl) solution. RTE vegetables and sprouts were dip-inoculated with Escherichia coli (E. coli) and Salmonella spp. and dip-treated with SAEW, NaOCl solution for 5 min. SAEW treatment significantly (p < 0.05) reduced the total aerobic mesophilic bacteria from Chinese celery, lettuce and daikon sprouts by 2.7, 2.5 and 2.45 log10CFU/g, respectively relative to un-treated. Pathogens were significantly (p < 0.05) reduced from Chinese celery, lettuce and daikon sprouts by 2.7, 2.8 and 2.8 log10CFU/g (E. coli) and 2.87, 2.91 and 2.91 log10CFU/g (Salmonella spp.), respectively following a SAEW treatment. SAEW and NaOCl solution showed no significant sanitization difference (p > 0.05). Results demonstrate that SAEW at low chlorine concentration and a near neutral pH is a potential non-thermal food sanitizer that could represent an alternative to NaOCl solution and would reduce the amount of free chlorine used in fresh-cut vegetables industry, since the same microbial reduction as NaOCl solution is obtained.
The sanitization efficacy of slightly acidic electrolyzed water (SAEW) against food pathogens on 2.7, 2.8 and 2.8 log10CFU/g (E. coli) and 2.87, 2.91 and 2.91 log10CFU/g (Salmonella spp.), respectively following a SAEW treatment. SAEW and NaOCl solution showed no significant sanitization difference (p > 0.05). Results demonstrate that SAEW at low chlorine concentration and a near neutral pH is a potential non-thermal food sanitizer that could represent an s industry, since the same microbial reduction as NaOCl solution is obtained.
Suspension quantitative germicidal test showed that electrolyzed oxidizing water (EO water) was an efficient and rapid disinfectant. Disinfection rates towards E. coli (available chlorine concentration ACC: 12.40 mg/L) and Staphylococcus aureus (ACC: 37.30 mg/L) could reach 100% at 1 and 3 min, respectively. Disinfection mechanism of EO water was investigated at a molecular biological level by detecting a series of biochemical indices. The results showed that the dehydrogenase activities of E. coli and S. aureus decreased rapidly, respectively, at the rates of 45.9% and 32% in the 1st minute treatment with EO water. EO water also improved the bacterial membrane permeability, causing the rise of conductivities and the rapid leakages of intracellular DNA, K+, and proteins in 1 min. The leakages of DNA and K+ tended to slow down after about 1 min while those of proteins began to decrease a little after reaching the peak values. The sodium dodecyl sulfonate polyacrylamide gel electrophoresis (SDS-PAGE) showed that EO water destroyed intracellular proteins. The protein bands got fainter and even disappeared as the treatment proceeded. EO water s effects on the bacterial ultrastructures were also verified by the transmission electronic microscopy (TEM) photos. The disinfection mechanism of EO water was composed of several comprehensive factors including the destruction of bacterial protective barriers, the increase of membrane permeability, the leakage of cellular inclusions, and the activity decrease of some key enzymes.
Microbe(s): Escherichia coli, Staphylococcus aureus, Salmonella spp.
In the current study, the effectiveness of slightly acidic electrolyzed water (SAEW) on an in vitro inactivation of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella spp. was evaluated and compared with other sanitizers. SAEW (pH 5.6, 23 mg/l available chlorine concentration; ACC; and 940 mV oxidation reduction potential; ORP) was generated by electrolysis of dilute solution of HCl (2%) in a chamber of a non-membrane electrolytic cell. One milliliter of bacteria suspension (ca. 10-11 log10CFU/ml) was mixed with 9 ml of SAEW, strong acidic electrolyzed water (StAEW; ca. 50 mg/l ACC), sodium hypochlorite solution (NaOCl; ca.120 mg/l ACC) and distilled water (DW) as control and treated for 60 s. SAEW effectively reduced the population of E. coli, S. aureus and Salmonella spp. by 5.1, 4.8, and 5.2 log10CFU/ml. Although, ACC of SAEW was more than 5 times lower than that of NaOCl solution, they showed no significant bactericidal difference (p > 0.05). However, the bactericidal effect of StAEW was significantly higher (p < 0.05) than SAEW and NaOCl solution in all cases. When tested with each individual test solution, E. coli, S. aureus and Salmonella spp. reductions were not significantly different (p > 0.05). These findings indicate that SAEW with low available chlorine concentration can equally inactivate E. coli, S. aureus and Salmonella spp. as NaOCl solution and therefore SAEW shows a high potential of application in agriculture and food industry as an environmentally friendly disinfection agent.
Antimicrobial effect of slightly acidic electrolyzed water (SAEW: pH 5.6 0.1, 20.5 1.3 mg/L available chlorine concentration; ACC) against indigenous aerobic mesophiles and inoculated Escherichia coli and Salmonella spp. on fresh strawberry was assessed. The antimicrobial effect of SAEW was compared with that of strong acidic electrolyzed water (StAEW) and sodium hypochlorite (NaOCl) solution. SAEW effectively reduced total aerobic mesophilic bacteria from strawberries by 1.68 log10CFU/g and was not significantly different from that ofNaOCl solution (p > 0.05). Antimicrobial effect of SAEW against Salmonella spp. andE. coli was indicated by a more than 2 log10CFU/g reduction of their population andthe effect was not significantly different from that of NaOCl solution and StAEW at similar treatment conditions (p > 0.05). From these findings, SAEW with a near-neutral pH and low available chlorine concentration exhibits an equivalent bactericidal effectiveness to NaOCl solution and thus SAEW is a potential sanitizer that would be used as an alternative for StAEW and NaOCl solution in the fresh fruit and vegetables industry.
Effects of alkaline electrolyzed water (AlEW), acidic electrolyzed water (AcEW), 100 ppm sodium hypochlorite (NaClO), deionized water (DIW), 1% citric acid (CA) alone, and combinations of AlEW with 1% CA (AlEW + CA), in reducing the populations of spoilage bacteria and foodborne pathogens on cabbage were investigated at various dipping times (3, 5, and 10 min) with different dipping temperatures (1, 20, 40, and 50 C). Inhibitory effect of the selected optimal treatment against Listeria monocytogenes and Escherichia coli O157 : H7 on cabbage were also evaluated. Compared to the untreated control, AlEW treatment most effectively reduced the numbers of total bacteria, yeast, and mold, followed by AcEW and 100-ppm NaClO treatments. All treatments dip washed for 5 min significantly reduced the numbers of total bacteria, yeast, and mold on cabbage. With increasing dipping temperature from 1 to 50 C, the reductions of total bacteria, yeast, and mold were significantly increased from 0.19 to 1.12 log CFU/g in the DIW wash treatment (P < 0.05). Combined 1% CA with AlEW treatment at 50 C showed the reduction of around 3.98 and 3.45 log CFU/g on the total count, and yeast and mold, effective reduction of L. monocytogenes (3.99 log CFU/g), and E. coli O157 : H7 (4.19 log CFU/g) on cabbage. The results suggest that combining AlEW with CA could be a possible method to control foodborne pathogens and spoilage bacteria effectively on produce.
This study investigated residual bacteria and different food types left on tableware items after various washing and sanitization protocols. Escherichia coli K-12 and Staphylococcus epidermidis were inoculated into whole milk and soft cream cheese. The milk was used to contaminate regular drinking glasses and the cheese was used to contaminate plates and silverware. These tableware items were washed in manual (43 C) and mechanical (49 C) washers and sanitized with different sanitizers (24 C) for 5 s. Quaternary ammonium compound, sodium hypochlorite, peroxyacetic acid, neutral electrolyzed water (NEW), and a combination of citric acid with sodium dodecylbenzene sulfonate (acidic formulation) were used as the chemical sanitizers. Tap water was used as a control. Results showed that at least 5-log reductions in both bacterial numbers were achieved for all sanitizers in both types of washers, except for the control. With mechanical dishwashing, the NEW and acidic formulation treatments reduced bacterial populations by >6.9 and >6.0 log CFU per tableware item, respectively. With the manual operation, bacterial numbers were reduced by >5.4 and >6.0 log CFU per tableware item, respectively. This study revealed that NEW and the acidic formulation are as effective as the other chemical sanitizers for food contact surface sanitization in manual and mechanical ware washing.
Food safety issues and increases in food borne illnesses have promulgated the development of new sanitation methods to eliminate pathogenic organisms on foods and surfaces in food service areas. Electrolyzed oxidizing water (EO water) shows promise as an environmentally friendly broad spectrum microbial decontamination agent. EO water is generated by the passage of a dilute salt solution (1% NaCl) through an electrochemical cell. This electrolytic process converts chloride ions and water molecules into chlorine oxidants (Cl2, HOCl/ClO-). At a near-neutral pH (pH 6.3-6.5), the predominant chemical species is the highly biocidal hypochlorous acid species (HOCl) with the oxidation reduction potential (ORP) of the solution ranging from 800 to 900 mV. The biocidal activity of near-neutral EO water was evaluated at 25 C using pure cultures of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Treatment of these organisms, in pure culture, with EO water at concentrations of 20, 50, 100, and 120 ppm total residual chlorine (TRC) and 10 min of contact time resulted in 100% inactivation of all five organisms (reduction of 6.1-6.7 log10 CFU/mL). Spray treatment of surfaces in food service areas with EO water containing 278-310 ppm TRC (pH 6.38) resulted in a 79-100% reduction of microbial growth. Dip (10 min) treatment of spinach at 100 and 120 ppm TRC resulted in a 4.0-5.0 log10 CFU/mL reduction of bacterial counts for all organisms tested. Dipping (10 min) of lettuce at 100 and 120 ppm TRC reduced bacterial counts of E. coli by 0.24-0.25 log10 CFU/mL and reduced all other organisms by 2.43-3.81 log10 CFU/mL.
A study was conducted to investigate the effects of spray washing broiler carcasses with acidified electrolyzed oxidizing water (EO) or sodium hypochlorite (HOCl) solutions for 5, 10, or 15 s. Commercial broiler carcasses were contaminated with 0.1 g of broiler cecal contents inoculated with 105 cells of Campylobacter and 105 cells of nalidixic acid-resistant Salmonella. Numbers of bacteria recovered from unwashed control carcasses were 6.7, 5.9, 6.3, and 3.9 log10 cfu/mL for total aerobic bacteria, Escherichia coli, Campylobacter, and Salmonella, respectively. Washing in either EO (50 mg/L of sodium hypochlorite, pH 2.4, oxidation reduction potential of 1,180 mV) or HOCl (50 mg/L of sodium hypochlorite, pH 8.0) significantly reduced the levels of bacteria recovered from carcasses (P < 0.05). Carcasses washed with EO had slightly lower levels of total aerobic bacteria (0.3 log10 cfu/mL) and E. coli (0.2 log10 cfu/mL) than HOCl-treated carcasses; however, populations of Campylobacter and Salmonella were comparable after washing in either solution. Increasing the carcass washing time from 5 to 10 s lowered the levels of total aerobic bacteria (6.1 vs. 5.8 log10 cfu/mL), E. coli (4.6 vs. 4.1 log10 cfu/mL), Campylobacter (5.2 vs. 4.2 log10 cfu/mL), and Salmonella (2.0 vs. 1.2 log10 cfu/mL), but no further microbiological reductions occurred when washing time was extended from 10 to 15 s. Data from the present study show that washing poultry carcasses with EO is slightly better (total aerobic bacteria and E. coli) or equivalent to (Campylobacter and Salmonella) washing with HOCl. Washing broiler carcasses for a period equivalent to 2 inside-outside bird washers (10 s) provided greater reductions in carcass bacterial populations than periods simulating 1 (5 s) or 3 inside-outside bird washers (15 s).
Electrolyzed - oxidizing (EO) water is a relatively new method that has been utilized for killing pathogens in agriculture, medical sterilization and food sanitation. This water is generated by passing sodium chloride solution through EO water generator. In this study, the EO water was used to treat holy basil inoculated with Escherichia coli. The initial pH and oxidation - reduction potential (ORP) of EO water were 2.09 and 1200 mV, respectively. The treatments changed ORP to 800,950 and 1100 mV. The contact times were 10,30 and 60 min. In pure culture, E. coli viable counts in the sample treated with EO water were reduced to undetectable levels at all ORP and times. However no reduction in E. coli counts was achieved in the control sample (treated with deionized water). The initial population of E. coli was about 8.5 log10 CFU / ml which was inoculated on 5 g of holy basil. Results showed that the treatment treated with EO water was reduced about 2 log10 CFU / ml in ORP 800 and 950 mV, 4 log10 CFU / ml in ORP 1100 mV for 10 min. When the contact time increased to 30 min, the reduction of E. coli count was about 3 log 10 CFU / ml in ORP 950 mV and 5 log10 CFU / ml in ORP 1100 mV. But the reduction was not different from 10 min when treated with ORP 800 mV. When the contact time increased to 60 min, the reduction of E. coli count was about 3 log10 CFU / ml in ORP 800 mV, 4 log10 CFU / ml in ORP 950 mV. and 6 log10 CFU / ml in ORP 1100 mV. These results could be concluded that the ORP of EO water and contact time significantly inactivated E. coli.
For reducing bacterial contamination, electrolyzed oxidizing water (EO water) has been used to reduce microbial population on seafood and platform of fish retailer. The specimens of tilapia were inoculated with Escherichia coli and Vibrio parahaemolyticus, and then soaked into EO water for up to 10 min. EO water achieved additional 0.7 log CFU/cm2 reduction than tap water on E. coli after 1 min treatment and additional treatment time did not achieved additional reduction. EO water treatment also reduced V. parahaemolyticus, by 1.5 log CFU/cm2 after 5 min treatment and achieved 2.6 log CFU/cm2 reduction after 10 min. The pathogenic bacteria were not detected in EO water after soaking treatment. In addition, EO water could effectively disinfect the platform of fish retailer in traditional markets and fish markets.
The effectiveness of electrolyzed oxidizing anode (EOA) water (oxidation-reduction potential, 1,120 mV; pH 2.0) as a sanitizer for use in abattoirs was compared with the iodophor (IOD) Mikroklene (25 ppm), a sanitizer approved for use by regulatory authorities in Canada and the United States. A total of 240 swab (100 cm2) samples were obtained from 4 sites on the kill floor and 16 sites in the secondary processing areas, during two visits within a 4-week period to each of three meat packing plants, processing < or =50 animals per week. Swabs were obtained 12 h after the application of IOD and EOA and were analyzed for the presence of total aerobic bacteria, total coliforms, and total Escherichia coli. Total aerobic bacteria (log CFU/ 100 cm2) recovered from the 20 sample sites were lower (P < 0.0001) in EOA as compared with IOD (2.94 +/- 0.12 versus 3.75 +/- 0.12, respectively). Plant A was 1.5 times more likely (P < 0.0001) to have a sampling site positive for the presence of coliforms and E. coli than plants B and C. There was no difference (P > 0.05) between treatment IOD or EOA in the likelihood of obtaining a positive sample for the presence of total coliforms or E. coli among the three plants. When the kill floor and secondary processing areas are compared, the likelihood of obtaining a sample positive for coliforms or E. coli was similar (P > or = 0.05). Results indicate that EOA was more effective than IOD in reducing populations of total aerobic bacteria on equipment surfaces in the three meat packing plants studied. Because the likelihood of obtaining a positive sample for coliforms or E. coli in EOA as compared with IOD was similar, EOA may be a suitable alternative or complement to IOD as a sanitizer in small- to medium-sized abattoirs. Additional research is required to further evaluate the effectiveness of EOA to sanitize processing equipment on the basis of subsequent isolation of aerobes, coliforms, and E. coli from meat products.
In 1999 the foodborne pathogens Salmonella, Listeria, Campylobacter, and Escherichia coli (both O157 and non-O157) were estimated to cause more than 6 million illnesses and approximately 9000 deaths each year. However, the most recent Centers for Disease Control and Prevention report on the sources and incidence of foodborne disease, released in 2004, has shown a dramatic decrease in E. coli O157:H7 infections. Since raw beef products are the most frequently foodborne sources of these pathogens, the results of this report demonstrate that the microbiological quality of raw beef has improved greatly. During the intervening years, post-harvest interventions have continually improved, with new attention to hide decontamination and innovative treatments of carcasses. In addition, a system to hold and test beef trim or ground beef for E. coli O157:H7 before its release into commerce has provided an even greater level of safety. In this paper, we review the latest information on the prevalence of E. coli O157:H7 and other pathogens on beef, the evidence identifying the hide as the primary source of pathogens on beef carcasses, the efficacy of various hide and carcass interventions, and other developments that have led or have the potential to lead to even greater improvements in the microbial quality of beef.
During commercial processing, eggs are washed in an alkaline detergent and then rinsed with chlorine to reduce dirt, debris, and microorganism levels. The alkaline and acidic fractions of electrolyzed oxidizing (EO) water have the ability to fit into the 2-step commercial egg washing process easily if proven to be effective. Therefore, the efficacy of EO water to decontaminate Salmonella Enteritidis and Escherichia coli K12 on artificially inoculated shell eggs was investigated. For the in vitro study, eggs were soaked in alkaline EO water followed by soaking in acidic EO water at various temperatures and times. Treated eggs showed a reduction in population between > or = 0.6 to > or =2.6 log10 cfu/g of shell for S. Enteritidis and > or =0.9 and > or =2.6 log10 for E. coli K12. Log10 reductions of 1.7 and 2.0 for S. Enteritidis and E. coli K12, respectively, were observed for typical commercial detergent-sanitizer treatments, whereas log10 reductions of > or =2.1 and > or =2.3 for S. Enteritidis and E. coli K12, respectively, were achieved using the EO water treatment. For the pilot-scale study, both fractions of EO water were compared with the detergent-sanitizer treatment using E. coli K12. Log10 reductions of > or = 2.98 and > or = 2.91 were found using the EO water treatment and the detergent-sanitizer treatment, respectively. The effects of 2 treatments on egg quality were investigated. EO water and the detergent-sanitizer treatments did not significantly affect albumen height or eggshell strength however, there were significant affects on cuticle presence. These results indicate that EO water has the potential to be used as a sanitizing agent for the egg washing process.
Research was conducted to compare the effectiveness of electrolyzed oxidative (EO) water applied using an electrostatic spraying system (ESS) for killing populations of bacteria that are of concern to the poultry industry. Populations of pathogenic bacteria (Salmonella typhimurium, Staphylococcus aureus, and Listeria monocytogenes), and the indicator bacterium Escherichia coli were applied to eggs and allowed to attach for 1 h. EO water completely eliminated all Salmonella typhimurium on 3, 7, 1, and 8 out of 15 eggs in Repetitions (Rep) 1, 2, 3, and 4, respectively, even when very high inoculations were used. EO water completely eliminated all Staphylococcus aureus on 12, 11, 12, and 11 out of 15 eggs in Rep 1, 2, 3, and 4, respectively. EO water completely eliminated all Listeria monocytogenes on 8, 13, 12, and 14 out of 15 eggs in Reps 1, 2, 3, and 4, respectively. EO water completely eliminated all Escherichia coli on 9, 11, 15, and 11 out of 15 eggs in Reps 1, 2, 3, and 4, respectively. Even when very high concentrations of bacteria were inoculated onto eggs (many times higher than would be encountered in industrial situations), EO water was found to be effective when used in conjunction with electrostatic spraying for eliminating pathogenic and indicator populations of bacteria from hatching eggs.
Recently, several reports about sterilization effect of electrolyzed water have been published. The electrolyzed water is expected as one of attractive application for sanitation of fresh food, however, to install this electrolyzed water, we have to clear the potential of the microorganism control for real food. In this paper, we try to reveal the mechanism of the microorganism control, and also try to check the food quality change during the treatment. Therefore, to evaluate the effect of the electrolyzed water, we examined the several test for making sterilization mechanism clear and observed microorganism behavior on food surface. At first, for the purpose of making sterilization effects clear in vitro condition, we did microorganism test with several injection ratio and number. Then, we studied the effects of catalase on the enumeration of stressed Escherichia coli cells after acidic electrolyzed water treatment. Moreover, we studied sterilization effect of acidic electrolyzed water for E. coli on an agar block on the assumption as one of food model. In addition, we studied sterilization effects for sliced raw tuna as one sample of food surface treatment. The change in the quality of food surface was observed by scanning electron microscope, color meter and so on. Steriliaation effects are dependent the condition of injection ratio and mixing numbers. These results suggest that it is important to keep available chlorine concentration for keeping the potential to the microorganisms control. The increasing of E. coli number with the addition of catalase was suggested that the weak concentration of electrolyzed water gave the injured microbes. The Observation of cultivated E. coli behavior on agar block showed the microorganism behavior. Acidic electrolyzed water sterilizes microorganisms on sliced raw tuna, however, after treatment, the color change of surface of tuna and the protein denaturation were observed. These results suggest that when the electrolyzed water treatment is applied to control the microorganism on surface, the effect against food surface must be considered.
Acidic electrolyzed water (acidic EW), which is prepared by the electrolysis of an aqueous NaCl solution, has recently become of great importance for disinfection in a variety of fields, including medicine, the food industry and agriculture. In a previous paper we showed that: 1) acidic EW is a mixture of hypocholorite ion, hypochlorous acid and chlorine, depending upon the pH; 2) hypochlorous acid is primarily responsible for disinfection in the case of Escherichia coli K12 and Bacillus subtilis PCI219, both in clean culture media. In practice, however, the use of acidic EW is in many cases severely hampered due to the presence of a variety of non-selective reducing agents. In view of the salient nature of acidic EW, it is therefore strongly urged to establish an optimum way to use acidic EW in a variety of systems. The present paper is the first report on our attempt along this line in order to characterize the nature of the chemical changes that the bactericidal activity of the acidic EW deteriorates in the presence of organic materials, which include amino acids and proteins.
Hypochlorous acid (HOCl) is probably the most widely used disinfectant worldwide and has an important role in inflammatory reaction and in human resistance to infection. However, the nature and mechanisms of its bactericidal activity are still poorly understood. Bacteria challenged aerobically with HOCl concentrations ranging from 9.5 to 76 M exhibit higher ability to form colonies anaerobically than aerobically. Conversely, aerobic plating greatly increased lethality after an anaerobic HOCl challenge, although anaerobic survival did not depend on whether HOCl exposure was aerobic or anaerobic. Even a short transient exposure to air after anaerobic HOCl challenge reduced anaerobic survival, indicative of immediate deleterious effects of oxygen. Exposure to HOCl can cause lethal DNA damage as judged by the fact that recA sensitivity to HOCl was oxygen dependent. Antioxidant defenses such as reduced glutathione and glucose-6-phosphate dehydrogenase were depleted or inactivated at 10 M HOCl, while other activities, such as superoxide dismutase, dropped only above 57 M HOCl. Cumulative deficiencies in superoxide dismutase and glucose-6-phosphate dehydrogenase rendered strains hypersensitive to HOCl. This indicates that part of HOCl toxicity on Escherichia coli is mediated by reactive oxygen species during recovery.

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