Available Chlorine Concentration Research Articles

Disinfection effect of adding slightly acidic electrolyzed water to artificial seawater under the condition of static hybrid

Mixed solution of slightly acidic electrolyzed water (SAEW) and artificial seawater was used to investigate the disinfection potential of SAEW in artificial seawater. Inoculated Vibrio parahaemolyticus (suspended in 3% sodium chloride alkaline peptone water and 0.85% sodium chloride water, respectively) was subjected to different mixed-SAEW and SAEW immersion treatments (5-20 mg/L available chlorine concentration (ACC)). In the presence of organic matter, 4.07 logCFU/mL significant reduction (p<0.05) was achieved after treating with 20 mg/L mixed-SAEW for 15 min. There was 5.13 logCFU/mL reduction after treating with 15 mg/L SAEW for 15 min. For V. parahaemolyticus suspended in 0.85% sodium chloride solution, it was undetected after 30 s SAEW treatment (5 mg/L ACC) or 120 s mixed-SAEW treatment (10 mg/L ACC). At a ratio of SAEW and artificial seawater at 1:15 (V/V), SAEW could inactivate V. parahaemolyticus to undetectable level in artificial seawater in one minute, which was comparable with UV treatment of 10 W. The results indicated high sanitization potential of SAEW against V. parahaemolyticus in aquaculture seawater. Keywords: slightly acidic electrolyzed water, disinfection, inactivation, Vibrio parahaemolyticus, artificial seawater, ultraviolet DOI: 10.25165/j.ijabe.20201302.4194 Citation: Wang C F, Huang X L, Wang S, Yu Y, Zhu S M, Ye Z Y. Disinfection effect of adding slightly acidic electrolyzed water to artificial seawater under the condition of static hybrid. Int J Agric & Biol Eng, 2020; 13(2): 218–222.

Microbicidal effects of slightly acidic hypochlorous acid water and weakly acidified chlorous acid water on foulbrood pathogens.

Paenibacillus larvae and Melissococcus plutonius are bacterial pathogens of honey bee brood. As decontamination of beekeeping equipment, including combs, is essential to control these pathogens, we evaluated the disinfecting effects of slightly acidic hypochlorous acid water (SAHAW) and weakly acidified chlorous acid water (WACAW) on the pathogens. Both disinfectants exhibited strong disinfecting effects in suspension tests under no organic matter conditions and reduced both pathogens by >5 log10 CFU/ml. Although the microbicidal activity of SAHAW with an available chlorine concentration (ACC) of 10–30 ppm was decreased by organic matter, it reduced viable P. larvae spores in combs more efficiently than H2O when the comb was not as dirty. However, its efficacy on combs decreased at 4°C and when overused or highly contaminated combs were tested. WACAW with an ACC of ≥600 ppm had a higher disinfecting capacity than SAHAW, and efficiently removed P. larvae spores from combs even under organic matter-rich and low-temperature conditions. However, even by WACAW, the amount of viable spores in combs was not markedly reduced depending on contamination levels and P. larvae genotypes. These results suggest the usefulness of both disinfectants for decontaminating beekeeping equipment depending on the situations expected.

Application of slightly acidic electrolyzed water and ultraviolet light for Salmonella enteritidis decontamination of cell suspensions and surfaces of artificially inoculated plastic poultry transport coops and other facility surfaces

The efficiency of combination treatment of slightly acidic electrolyzed water (SAEW) and ultraviolet light (UV) for inactivation of Salmonella enteritidis (S. enteritidis) on the surface of plastic poultry coops and other facility surfaces was evaluated in the presence of organic matter. The bactericidal activities of SAEW, UV + SAEW, and composite phenol (CP) for inactivating S. enteritidis were also compared. Moreover, a model of UV + SAEW treatment of plastic transport coops with different times and available chlorine concentrations (ACC) was developed using multiple linear regression analysis. There are differences between SAEW and CP inactivation of S. enteritidis on coops, stainless steel, and glass surfaces (P < 0.05), and there are no differences between SAEW and CP on tire surfaces (P > 0.05). Disinfection of some rough material surfaces with SAEW treatment alone under feces interference on poultry farms may need a longer treatment time and/or a higher ACC than smooth surfaces. The combined treatment of UV and SAEW showed higher inactivation efficiency of S. enteritidis compared to CP and SAEW treatment alone (P < 0.05) in pure cultures or on the facility surfaces. A complete 100% inactivation of S. enteritidis on plastic poultry coop surfaces was obtained by using UV + SAEW with an ACC of 90 mg/L for more than 70 s. The established model had a good fit that was quantified by the determination coefficient R2 (0.93) and a lack of fit test (P > 0.05). The bactericidal efficiency of UV + SAEW increased with greater ACC and increasing time. The findings of this study indicate that the combination treatment of UV and SAEW may be a promising disinfection method and could be used instead of SAEW alone, especially on rough materials in the presence of organic matter on poultry farms.

The synergistic effects of slightly acidic electrolyzed water and UV-C light on the inactivation of Salmonella enteritidis on contaminated eggshells

Salmonella enteritidis (S. enteritidis) infection has been recognized as one of the most common bacterial causes of human gastroenteritis worldwide and is closely associated with eggs. Slightly acidic electrolyzed water (SAEW) is an emerging environmentally friendly technology for disinfecting eggshell surfaces to remove dirt and pathogenic microorganisms. However, the efficiency of SAEW could be affected by the presence of manure. UV-based advanced oxidation processes have been studied to improve the microorganism's inactivation effect of disinfection. Therefore, in this study, the synergistic bactericidal efficacy of SAEW and UV-C light (ultraviolet lamp, λ = 254 nm) for inactivation of S. enteritidis on artificially inoculated eggshells with or without manure was evaluated, and the bactericidal efficacy of different combination treatments of SAEW and UV-C light was compared. Without manure interference, complete inactivation (reduction of 6.54 log10 CFU/g) of S. enteritidis on the surface of eggshells was achieved following a 4-min treatment with SAEW+UV at an available chlorine concentration (ACC) of 20 mg/L. In the presence of manure, a 3.02 log reduction was achieved following a 4-min treatment with SAEW+UV at an ACC of 30 mg/L. Simultaneous treatment with SAEW and UV light exhibits higher bactericidal activity for eggshells than other combination process methods with UV and SAEW. The results suggest that the combined treatment of SAEW+UV is a novel method to enhance the microbial safety of eggshells.

Destruction of Cyanide and Removal of Copper from Waste Printed Circuit Boards Leach Solution Using Electro-Generated Hypochlorite Followed by Magnetite Adsorption

The removal of the cyanide and copper (Cu) from the waste printed circuit boards (WPCBs) cyanide leach solution through the alkaline chlorination using electro-generated hypochlorite (NaOCl) followed by magnetite (Fe3O4) adsorption is investigated. The efficiency of the destruction of cyanide and precipitation of Cu was increased with increasing the concentration of free available chlorine in NaOCl. More than 99% of free cyanide and 76% of Cu were removed under the following conditions: concentration of chlorine in electro-generated NaOCl, 5.2 g/L; volume ratio of NaOCl/leach solution, 1; pH, ~9.8; ambient temperature for 12 h. Then, magnetite adsorption for selective removal of remaining Cu (50.5 mg/L) was selected and more than 99% of copper ion was successfully removed with dosage 10g/100mL, shaking speed 150 rpm within 30 min. The results revealed that the alkaline chlorination using electro-generated NaOCl followed by magnetite adsorption could completely remove the cyanide and Cu, remaining Au in the final solution.

Effect of pH and chlorine concentration of slightly acidic electrolyzed water on the buckwheat sprouts during germination

Previous research found that slightly acidic electrolyzed water (SAEW) promoted the growth of buckwheat sprouts and the accumulation of bioactive γ-aminobutyric acid (GABA), but mechanisms had not been reported. At present study, the effects of pH and available chlorine concentration (ACC) of SAEW on buckwheat sprouts were investigated. It showed that SAEW1 with moderate pH (5.71 ± 0.03) resulted in the highest accumulation of GABA ((113.5 mg/100 g) in comparison with SAEW 2 (pH 5.01 ± 0.05) and SAEW 3 (pH 6.41 ± 0.04) treatments. Moreover, the higher ACC of SAEW was, the more content of GABA it accumulated, which suggested that ACC played an important role during germination of buckwheat. The above results were demonstrated by the investigation of glutamic acid decarboxylase activity during germination of buckwheat. However, it showed that higher ACC of SAEW had adverse impact on the growth of buckwheat sprouts while pH of SAEW had no adverse impact on the growth of buckwheat sprouts. Generally, appropriate pH and ACC of SAEW should be considered in the application of the production of buckwheat sprouts. Practical applications SAEW that had neutral pH (5.0–6.5) and lower ACC (10–30 mg/L) had been used in the production of sprouts. SAEW could promote the dual accumulation of GABA and rutin in tartary buckwheat sprouts. Obtaining the specific parameters of SAEW would beneficial for the most accumulation of these functional components when it is used for sprouts production.

Difference between the Actual and Labeled Concentrations of Several Domestic Brands of Sodium Hypochlorite.

Sodium hypochlorite (NaOCl) is extensively used in root canal treatment and its efficacy depends on the concentration of free available chlorine (FAC). This study aimed to assess the chlorine content of 10 domestically manufactured household bleach products available in the Iranian market and evaluate the effect of temperature, time and daily bottle uncapping on FAC concentration and pH of these products. One-liter bottles of 10 available brands of household bleach (n=4 of each brand) were collected and randomly divided into four groups (n=10). Two groups were refrigerated at 4°C while the remaining two were stored at room temperature. One group of refrigerated and one group of room temperature samples were subjected to daily bottle uncapping followed by agitation and recapping for 3 months (six times a week to simulate weekly office work). The remaining bottles remained untouched and served as controls. The concentration of FAC in each sample was measured using the iodometric titration assay, and the pH was measured using a calibrated pH-meter at baseline and 1, 2 and 3 months. The results were analyzed using the one-way ANOVA and t-test. The mean concentration of FAC in the solutions was 4.87±0.19% at baseline. The measured concentration of sodium hypochlorite was different from the labeled value. The concentration of FAC decreased over time in all samples; the greatest reduction occurred in room temperature samples subjected to daily uncapping while the smallest reduction occurred in refrigerated, capped bottles (19% and 1.9%, respectively). The pH of all products decreased over time. The mean reduction in pH was 1.1 for the samples stored at room temperature for 3 months and 0.8 for the refrigerated samples. This in vitro study showed that the expected concentration of sodium hypochlorite solution made of household bleach for endodontic purposes is different from its actual concentration.

The application of slightly acidic electrolyzed water in pea sprout production to ensure food safety, biological and nutritional quality of the sprout

Slightly acidic electrolyzed water (SAEW) with available chlorine concentrations (ACC) of 35 and 70 mg/L is used instead of regular production water for soaking pea (Pisum sativum L.) seeds and spraying the sprouts during seed sprouting. Sodium hypochlorite (NaOCl) with the same ACC and tap water are used as a control in this study. The population of total bacteria, coliform, yeast and mold are determined at day 2, day 5, day 8, and day 11, respectively during seed sprouting. The biological indicators, nutritive indicators, and nitrite content after the sprouts are harvested are measured as well. The results indicate that when treated with SAEW, the counts of total bacteria, coliform, yeast and mold are reduced by 0.99–1.58 log CFU/g, 0.57–1.02 log CFU/g, and 1.01–1.22 log CFU/g respectively, compared to tap water treatment. Fresh weight, length, and edible rate of the sprouts significantly improve when treated with SAEW (p < 0.05). No evident adverse effects are observed in the nutritive indicators after SAEW treatment. In fact, a slight improvement (soluble sugar, flavonoid) was evident. Moreover, after a storage period of 7 d, the nitrite content of the sprouts was significantly lower in the SAEW treated samples than in any of other treatments. Therefore, SAEW could be a promising application in the production of pea sprouts to ultimately improve food safety.

Optimization of a wet scrubber with electrolyzed water spray—Part I: Ammonia removal

ABSTRACTElectrolyzed water (EW) is an effective disinfectant with a wide range of pH. EW in acid range was proved to be an ammonia absorbent which make it valuable for wet scrubbers used in animal feeding operations (AFOs). This study aimed to optimize the design and operating parameters of a wet scrubber with EW spray for ammonia removal, based on the size distribution of droplets, the property of EW and the reduction efficiency of ammonia. The optimized parameters included droplet size, nozzle flow rates, pH and available chlorine concentration (ACC) of EW, nozzle number at single stage, stage number, initial ammonia concentration and air speed in the duct. The ammonia removal efficiency increased with the decrease of droplet size and the increase of flow rate. The pH values of EW showed significant influence on ammonia removal efficiency (P ˂ 0.05), while ACC of the EW showed no significant influence (P > 0.05). For inlet ammonia concentration of 70 ppm with one and three spray stages, the wet scrubber with EW (pH = 1.35) spray was able to reduce 55.8 ± 4.3 % and 97.2 ± 3.0 % of ammonia, respectively, when the nozzles with 0.9 mm orifice diameter operated at a flow rate of 1.20 L min-1. Response surface analysis showed that orifice diameter, nozzle flow rate, and their combination were all significant factors impacting ammonia removal efficiency for both pH =1.35 and 5.50 at a 95% confidence level. Optimal ammonia removal efficiency was obtained at orifice diameter 0.9 mm and flow rate 1.20 L min-1 within the selected range. The results of this study demonstrated that wet scrubber with EW spray could be a very effective and feasible ammonia mitigation technology for animal feeding operation.Implications: It is difficult to effectively reduce ammonia emitted from the animal feeding operations (AFOs). Both the acidity and disinfection effects of electrolyzed water (EW) make it a potential absorbent used for spray in wet scrubber to reduce the ammonia and microorganisms. Based on some preliminary field test results, lab tests were conducted to optimize the design and operation parameters of a wet scrubber with EW spray to improve the ammonia removal efficiency. A better understanding of the application and influence factors of the wet scrubber with EW spray can contribute to effective mitigation of ammonia emission from animal houses and improve the atmosphere air quality.

Optimization of a wet scrubber with electrolyzed water spray—Part II: Airborne culturable bacteria removal

ABSTRACTAirborne microorganisms, especially the pathogenic microorganisms, emitted from animal feeding operations (AFOs) may harm the environment and public health and threaten the biosecurity of the farm and surrounding environment. Electrolyzed water (EW), which was considered to be an environmentally friendly disinfectant, may be a potential spraying medium of wet scrubber for airborne microorganism emission reduction. A laboratory test was conducted to investigate the airborne bacteria (CB) removal efficiency of the wet scrubber by EW spray with different designs and operating parameters. Both the available choline (AC) initial loss rate and AC traveling loss rate of acidic electrolyzed water (AEW; pH = 1.35) were much higher than those of slightly acidic electrolyzed water (SAEW; pH = 5.50). Using one spraying stage with 4 m sec−1 air speed in the duct, the no detect lines (NDLs) of SAEW (pH = 5.50) for airborne Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis removal were all 50 mg L−1, whereas the NDLs of AEW (pH = 1.35) for airborne E. coli, S. aureus, and S. enteritidis removal increased to 70, 90, and 90 mg L−1, respectively. The NDLs of SAEW (pH = 5.50) for airborne E. coli, S. aureus, and S. enteritidis were lower than those of AEW (pH = 1.35) at single spraying stage. Increase in the number of stages lowered the NDLs of both SAEW (pH = 5.50) and AEW (pH = 1.35) for airborne E. coli, S. aureus, and S. enteritidis. EW with a higher available chlorine concentration (ACC) was needed at air speed of 6 m sec−1 to reach the same airborne CB removal efficiency as that at air speed of 4 m sec−1. The results of this study demonstrated that EW spray wet scrubbers could be a very effective and feasible airborne CB mitigation technology for AFOs.Implications: It is difficult to effectively reduce airborne bacteria emitted from animal feeding operations (AFOs). Electrolyzed water (EW) with disinfection effect and acidity is a potential absorbent for spray in wet scrubber to remove microorganisms and ammonia. Based on the field test results, a laboratory experiment we conducted this time was to optimize the design and operation parameters to improve the airborne bacteria removal efficiency. A better understanding of the EW application in the wet scrubber can contribute to the mitigation of airborne bacteria from animal houses and improve the atmosphere air quality.

Sanitization Efficacy of Slightly Acidic Electrolyzed Water against pure cultures of Escherichia coli, Salmonella enterica, Typhimurium, Staphylococcus aureus and Bacillus cereus spores, in Comparison with Different Water Hardness

The Influence of water source on the production of slightly acidic electrolyzed water (SAEW) and its sanitization efficacy were investigated. Two different water sources (tap water (TW) and underground water (UGW)) were applied to produce slightly acidic electrolyzed water (SAEW) at same setting current, with similar electrolyte flow rate (EFR) and concentration. Properties of SAEW were evaluated based on pH, Available chlorine concentration (ACC) and oxidation-reduction potential (ORP). Methods for the optimization of SAEW production process was examined to obtain high ACC value by implanting different types of electrolytes. Effect of ACC and pH of SAEW were evaluated in vitro towards inactivate foodborne pathogens. The results indicated that TW with hardness of 29 ppm produced effectively SAEW than through UGW (12 ppm) using electrolytes. Likewise, low water hardness could be reinforced by combining HCL with a salt (NaCl or KCL). The optimized SAEW production system was determined at 4% HCl + 2.0 M KCL with EFR of 2 mL/min and 4% HCl + 3.0 M KCL with EFR of 2 mL/min resulting in higher ACC value of 56.5 and 65.5 ppm, respectively using TW. Pathogenic vegetative cells were completely inactivated within 1 min of treatment in SAEW with 20 ppm. Viability observations using Confocal and TEM Microscopy, Flow cytometry, and antimicrobial activity were carried out to confirm the sanitizing effect and cell membrane disruption. Based on the experimental results obtained, it provides a foundation for future advancement towards commercial application of SAEW in the food and agricultural industries.

Flow cytometry and growth-based analysis of the effects of fruit sanitation on the physiology of Escherichia coli in orange juice.

Chlorine‐based solutions are commonly used to sanitize orange fruits prior to juice extraction. We used flow cytometry (FCM) to investigate the physiology of Escherichia coli following its subjection to chlorine‐based solutions and alternative sanitizing agents (H2O2 and organic acids). Green fluorescent protein (GFP)‐generating E. coli K‐12 were washed with 50–200 ppm available chlorine (AC), 1%–5% H2O2, 2%–4% citric acid, 4% acetic acid, or 4% lactic acid, after which they were added to 1.2 μm‐filtered orange juice (OJ). Cell physiology was investigated with FCM during storage at 4°C, and culturability was determined using plate counting. Analysis of GFP fluorescence allowed estimation of intracellular pH (pH i). FCM results demonstrated an inverse relationship between the concentration of AC or H2O2 and cellular health in OJ. Higher concentrations of sanitizer also resulted in a significantly greater number of viable but nonculturable (VBNC) cells. Real‐time FCM showed that supplementation of AC with 2% citric acid, but not with 100 ppm of Tween‐80, led to a significant reduction in pH i of the cells incubated in OJ, and that the majority of the reduction in pH i occurred during the first 2 min of incubation in OJ. Organic acids were found to be more effective than both AC and H2O2 in reducing the pH i, viability, and culturability of the cells in OJ. The results confirmed the hypothesis that consecutive subjection of E. coli to maximum legally permitted concentrations of sanitizers and OJ induces the VBNC state. Furthermore, we demonstrate successful application of FCM for monitoring the efficacy of washing procedures.

Modeling the degradation of acidic electrolyzed water and its ability to disinfect a dual-species biofilm

As a novel broad-spectrum disinfectant, acidic electrolyzed water (AEW) has been widely used, but it is generated on-site for one-time used and usually not stored. but “producing once for using once” is not a convenient mode for industrial application. This study focused on modeling the degradation of the available chlorine concentration (ACC) of AEW during storage and its ability to disinfect a dual-species biofilm formed by Salmonella Enteritidis and Pseudomonas fluorescens. The results showed that temperature had no significant effect on the ACC, while the ACC gradually decreased with time. The degradation process of the ACC could be fitted very well using the Weibull model. Dual-species biofilms comprising S. Enteritidis and P. fluorescens were inactivated by 20 and 40 mg/L AEW. The number of viable cells on stainless steel gradually decreased as the treatment time increased. Immersion for 10 and 30 min led to > 2 log CFU/cm2 and 4.5 log CFU/cm2 in decrease of the cells in dual-species biofilms when treated with 20 and 40 mg/L AEW, respectively. In addition, the dual-species biofilm displayed more resistance than the single-species biofilm. The findings presented herein could provide useful information for the application of AEW in food processing environments.

Slightly Acidic Electrolyzed Water Treatment Enhances the Main Bioactive Phytochemicals Content in Broccoli Sprouts via Changing Metabolism.

Changes in the content of bioactive phytochemicals in the broccoli sprouts subjected to different slightly acidic electrolyzed water (SAEW) treatments were investigated in the present study. The highest sulforaphane amount in broccoli sprouts treated with SAEW with an available chlorine concentration (ACC) of 50 mg/L was 11.49 mg/g in dry weight (DW), which increased by 61.2% compared to the control. SAEW treatment enhanced the sulforaphane content mainly by increasing the glucoraphanin (GRA) concentration due to the promotion of methionine metabolism and increased myrosinase activities. In addition, the relative anthocyanin contents of light-germinated broccoli under SAEW 50 treatment were 2.03 times that of broccoli sprouts with tap water treatment, and these contents were associated with an increase in phenylalanine ammonia lyase (PAL) activities and phenylalanine participation in biosynthesis. In summary, SAEW promotes metabolism to induce the accumulation of bioactive compounds in broccoli sprouts.

Red cabbage washing with acidic electrolysed water: effects on microbial quality and physicochemical properties

The effects of acidic electrolysed water (AEW) as ‘green’ technology on the microbiological and physicochemical properties of fresh-cut red cabbages were studied. Fresh-cut red cabbages and artificially inoculated red cabbages with Salmonella typhimurium DT104 were washed with distilled water (DW) and different available chlorine concentrations (ACC) of AEW for different times. AEW treatments significantly reduced the populations of native aerobic bacteria, molds, and yeasts, and artificially inoculated S. typhimurium DT104 compared with the DW-treated and untreated red cabbage samples. The effectiveness of AEW treatments was greatly enhanced with increasing ACC and treatment times. S. typhimurium DT104 were not detected in the washing water that were collected after the red cabbages treated by AEW. The surface colour, pH, and total phenolic contents did not significantly change when the red cabbages were washed with DW and AEW containing 100 mg/L available chlorine for 3 min. The anthocyanin contents and antioxidant activities of red cabbage were significantly reduced by 18.5 per cent for cyanidin, 22.1 per cent for pelargonidin, and 11.2 per cent for 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, however, the impacts on the nutritional benefits of red cabbage were considered as limited and acceptable. The optimal process condition of AEW for washing red cabbage was 100 mg/L ACC for 3 min. In these conditions, most of the native microflora were inactivated, and artificially inoculated S. typhimurium DT104 on the red cabbage were reduced by 40.2 per cent [3.67 log CFU/g (log10 colony-forming units per gram)] and with minimal losses of nutrients and antioxidant activity, as well as no requirement of decontamination treatment on the washing water after AEW treatment.

Inactivation kinetics of slightly acidic electrolyzed water combined with benzalkonium chloride and mild heat treatment on vegetative cells, spores, and biofilms of Bacillus cereus

Bacillus cereus can exist as vegetative cells, spores, and biofilms in food-processing environment, posing a big challenge for the food industry. The objective of this study was to examine the inactivation efficacy of slightly acidic electrolyzed water (SAEW) in combination with benzalkonium chloride (BAC) and mild heat treatment (50 and 60 °C) on B. cereus strains (ATCC 10987 and ATCC 14579). The inactivation efficacy of SAEW was found to be largely dependent on available chlorine concentration (ACC) level and exposure time as well as B. cereus strains and growth conditions. SAEW with ACC of 40 ppm reduced ATCC 10987 and ATCC 14579 vegetative cells to the non-detection limit within 30 s. and 1 min, respectively. Combination treatment with SAEW+60 °C for 10 min resulted in reductions of ATCC 10987 spores, ATCC 14579 spores, and ATCC 10987 biofilms at 0.76 logCFU/ml, 0.59 logCFU/ml, and 1.28 logCFU/cm2, respectively. While, treatment with SAEW+BAC + 60 °C for 10 min resulted in reductions of ATCC 10987 spores, ATCC 14579 spores, and ATCC 10987 biofilms at 1.91 logCFU/ml, 1.98 logCFU/ml, and 2.62 logCFU/cm2, respectively. The inactivation kinetics under different ACC of SAEW and in combination with BAC and mild treatment were determined by Weibull model. The calculated adjusted correlation coefficients (R2adj) and root mean sum of squared error (RMSE) values for all curves were found to be ranges from 0.95–0.99 and 0.04–0.23, respectively, indicating that the Weibull model precisely predicted the inactivation kinetics of B. cereus during SAEW in combination with BAC and mild heat treatments. These results suggest that SAEW in combination with BAC and mild heat may be used as an effective cleaning strategy against B. cereus in the food contact surfaces.

Primary concerns regarding the application of electrolyzed water in the meat industry

The application of electrolyzed water effectively reduces microbial contamination and has greatly contributed to delayed meat spoilage. However, concerns about applying electrolyzed water in the meat industry, which include the stability of available chlorine in various storage conditions, corrosion resistance and residual chlorate, have attracted much attention. In this study, primary concerns regarding acid electrolyzed water (AEW) and slightly acid electrolyzed water (sAEW) were evaluated in comparison to those of sodium hypochlorite (SH) widely used in meat processing plants. The results showed that closed and 4 °C storage conditions, which just declined about 30% ACC of available chlorine concentration (ACC), were more beneficial than open and 20 °C storage conditions for maintaining the stability of electrolyzed water, whereas no differences in stability were observed between dark and light storage. The decline of ACC positively depended on the concentrations of organic materials ranged from 0.1% to 0.3%, and the ACC was close to 10 mg/mL after 30 min trearment. The corrosion of AEW was equal to that of SH, but it was higher than that of sAEW. In addition, the concentration of residual chlorate in meat sprayed by electrolyzed water was less than meat sprayed by SH. The findings suggested that electrolyzed water is a great potential substitute for SH in the meat industry.

Label free-based proteomic analysis of proteins in Bacillus cereus spores regulated by high pressure processing and slightly acidic electrolyzed water treatment

To investigate the mechanism of high pressure processing (HPP, 200 MPa/20 min + 500 MPa/20 min) and slightly acidic electrolyzed water (SAEW, 44 mg/L available chlorine concentration (ACC)) on B. cereus spore inactivation, a label-free quantitative proteomics approach based on high-resolution mass spectrometry (MS) data was used. Quantification of 2810 proteins was obtained with high confidence. A total of 93 and 83 proteins showed significant differential abundance after HPP-SAEW and HPP treatments, respectively, and 21 proteins changed significantly when both treatments were compared. The results indicated that the spore cortex-lytic enzyme was upregulated 3.15 fold after HPP treatment, and the germination was influenced by ATP generation. The metabolic, degradation, signaling, and biosynthesis pathways were involved in HPP-SAEW mediated spore inactivation. Amino acid-biosynthetic and quorum sensing were the main KEGG pathways mediated by SAEW under HPP conditions. Specifically, our results showed that the phosphorylation of the Spo0A transcription factor was mediated by the downregulation of the ABC transporter ATP-binding protein, which was associated with inactivation of spores.

Inactivation Mechanism and Apoptotic-Like Changes in Aeromonas hydrophila Induced by Slightly Acidic Electrolyzed Water in Freshwater

Abstract. This study investigated the suppressive effect and the inactivation mechanism of slightly acidic electrolyzed water (SAEW) on . The experiment compared different inhibition effects with SAEW and two antibiotics, gentamicin and norfloxacin. The conditions of pH of 6.5, oxidation-reduction potential (ORP) of 890 mV, available chlorine concentration (ACC) of 28 mg L-1 of SAEW, and volume ratios of 1:10, 1:15, and 1:20 were used. Using exposure times of 5 and 10 min to analyze the inactivation mechanism of SAEW from the perspectives of cell membrane permeability, cell nuclear morphology, cell fluorescence staining, and other aspects, the anti-infection effects of SAEW were tested using tilapia () culture experiments. SAEW had a stronger bacteriostasis effect than the antibiotics used. SAEW can inhibit the ability to reproduce, causing abnormal cell morphology and cell elongation. The cell volume was increased with a change in the membrane permeability. The cell nuclear morphology was changed, further inducing apoptosis. Based on study of tilapia in a control group, the organs (intestine, stomach, and liver) developed different degrees of infection. No obvious infection was observed in muscle samples. After SAEW treatment, SAEW showed a better antibacterial effect and improvement effects on the inflammation and structural damage induced by , which could be helpful in aquaculture application. Keywords: A. hydrophila, Antibiotics, Anti-infection, Cell apoptosis, Membrane permeability, Slightly acidic electrolyzed water.

Viability assay of E. coli O157: H7 treated with electrolyzed oxidizing water using flow cytometry

Bacteria treated with chlorine-based sanitizer could enter into viable but non-culturable (VBNC) state, which may be underestimated its health risk. In this study, E. coli O157: H7 was treated with slightly acidic electrolyzed water (SAEW), acidic electrolyzed water (AEW) and sodium hypochlorite with different available chlorine concentrations (ACC). The reduction of population was determined, as well as the status of treated cells (viable and culturable, VBNC, dead) was assayed using flow cytometry combined with plate counting. Finally, the cell which cannot be detected using routine media was cultured in p-TSB to resuscitate. The results showed that the reduction of E. coli O157: H7 increased with increasing ACC of SAEW, AEW and sodium hypochlorite and the antimicrobial effect of electrolyzed oxidizing (EO) waters was much higher than sodium hypochlorite. SAEW, AEW and sodium hypochlorite with ACC of 30, 20 and 60 mg/L achieved E. coli O157: H7 colonies to non-detectable level on solid media. The results obtained from flow cytometric assay indicated that culturable cells after EO water and sodium hypochlorite treatments with increasing ACC firstly enter VBNC state and then transferred to dead status. VBNC E.coli was able to be resuscitated in p-TSB and therefore regarded as a potential risk for human health. E. coli O157: H7 in VBNC state after EO water treatment should be taken into consideration and complete inactivation could be achieved by elevated chlorine concentration.