Available Chlorine Concentration Research Articles

Characterization of slightly acidic electrolyzed water on effective disinfection against microbial safety and retention of phenolic compound in SAEW treated fresh romaine lettuce

Abstract This study investigated the effects of processing parameters, specifically the low rate and the combination of diluted HCl and salt (NaCl) at different concentrations, on the properties of the slightly acidic electrolyzed water (SAEW) that was produced. The properties of the SAEW that were analyzed included pH, oxidation-reduction potential (ORP), available chlorine concentrations (ACC), and generated hypochlorous acid (HClO) concentration. NaCl alone resulted in the lowest pH (<4) and the highest ORP values (>1000 mV). Increasing HCl concentrations significantly raised pH levels to greater than 5 and lowered ORP values of SAEW, with the highest pH (5.7) observed with 1.5% HCl and 5% NaCl. The highest HClO concentration of 19.65±1.03 mg/L was obtained with 1.5% HCl:5% NaCl. Interestingly, the concentration of NaCl showed no significant effects on the production of HClO. Furthermore, different concentrations of combined NaCl and HCl significantly influenced the inactivation efficiency on total aerobic bacteria count and changes in phenolic compound content. Increasing HCl concentrations from 0.5% to 2.0% led to an increase in the reduction of aerobic bacteria counts from 2.51 to 4.22 log CFU/g with 5% NaCl and from 2.49 to 3.52 log CFU/g with 10% NaCl. Flow rates significantly contributed to the change in HClO formation and altered the properties of the produced SAEW. Results indicated that SAEW treatment significantly reduced total aerobic bacteria counts. The lower flow rates (0.3 L/min) produced the highest log reductions. Additionally, SAEW treatment led to a reduction in phenolic content, even though considerable amount was retained at lower HClO concentrations. These findings offer valuable information on optimizing SAEW treatment protocols for enhancing microbial safety and extending the shelf life of fresh produce, while considering the impact on the content of phenolic compounds.

Application of Slightly Acidic Electrolyzed Water as a Potential Sanitizer in the Food Industry

The food industry has extensively explored postharvest microbial control, seeking viable technologies to ensure food safety. Although numerous chlorine-based commercial sanitizers serve this purpose, many are plagued by constraints such as instability and diminished disinfectant efficacy. These issues arise from exposure to organic matter in wash water, light, or air. As an innovative and promising alternative, slightly acidic electrolyzed water (SAEW) has emerged, captivating attention for its robust sterilization potential and eco-friendliness in agricultural and food sectors. SAEW generated via electrolysis of a diluted hydrochloric acid (HCl) solution with concentrations ranging from 2 to 6% or aqueous solution of sodium chloride (NaCl) in a nonmembrane electrolytic chamber is reported to possess equivalent antimicrobial properties as strong acidic electrolyzed water (StAEW). In contrast to traditional chlorine sanitizers, SAEW leaves less chlorine residue on sanitized foods such fresh-cut fruit and vegetables, meat, poultry, and aquatic products due to its low available chlorine concentration (ACC). Its near neutral pH of 5 to 6.5 not only renders it environmentally benign but also mitigates the production of chlorine gas, a contrast to low pH conditions seen in StAEW generation. The bactericidal effect of SAEW against various strains of foodborne pathogens is widely believed and accepted to be due to the combined action of high oxidation-reduction-potential (ORP) reactions and undissociated hypochlorite/hypochlorous acid (HOCl). Consequently, a burgeoning interest surrounds the potential of SAEW for sanitation in the food industry, offering an alternative to address shortcomings in sodium hypochlorite solutions and even StAEW. It has been hypothesized from a number of studies that SAEW treatment can increase the quality and nutritional value of harvested fruits, which in turn may enhance their ability to be stored. Therefore, SAEW is not only a promising sanitizer in the food industry but also has the potential to be an efficient strategy for encouraging the accumulation of bioactive chemicals in plants, especially if it is used extensively. This review encapsulates the latest insights concerning SAEW, encompassing its antimicrobial effectiveness, sanitization mechanism, advantages vis-à-vis other sanitizers, and plausible applications across the food industry.

Antibacterial mechanism of slightly acidic electrolyzed water against Pseudomonas arsenicoxydans A1 from greater amberjack (Seriola dumerili)

This study aimed to identify the specific spoilage organism (SSO) from the metamorphosed greater amberjack (Seriola dumerili) fish. Pseudomonas arsenicoxydans A1 was identified as SSO by culture-depending method. Further, the antibacterial efficacy of slightly acidic electrolyzed water (SAEW) was explored and the mechanism of action on P. arsenicoxydans A1 was studied. SAEW with 20–60 mg/L of available chlorine concentration (ACC) showed a good antibacterial effect on P. arsenicoxydans A1. The total number of colonies, growth curve, OD value at 260 nm and 280 nm, DNA fluorescence intensity, alkaline phosphatase (AKP), lactate dehydrogenase (LDH), superoxide dismutase (SOD), and catalase (CAT) enzyme activity and SEM results showed that SAEW could destroy the permeability and integrity of P. arsenicoxydans A1 cell membrane, and affect bacterial cell activity at metabolic, enzymatic and DNA level, which caused bacterial cell death. This study provided the application of SAEW in sterilization and preservation of raw fish fillets, which showed a promising effect on the growth of P. arsenicoxydans A1 in food cold chain.

Bactericidal efficacy of lithium magnesium silicate hydrosol incorporated with slightly acidic electrolyzed water in disinfection application against Escherichia coli.

In food safety implementation, bacterial inactivation is an imperative aspect of hygiene and sanitation. Studies on lithium magnesium silicate (LMS) hydrosol incorporated with slightly acidic electrolyzed water (SAEW) for decontamination of pathogenic bacteria are limited. This present study aimed to investigate the bactericidal efficacy of LMS hydrosol incorporated with SAEW against Escherichia coli. Optimum combination conditions of SAEW, hydrosol concentration, and available chlorine concentration (ACC) were optimized by response surface methodology under the central composite design against the growth of E. coli. The optimum combination conditions of exposure time, hydrosol concentration, and ACC were 9.5 minutes, 1.7%, and 20.5 ppm, respectively. The results showed that the increase in ACC led to inactivation in the survival of E. coli compared with the control (p<0.05). It can be concluded that the best combination percentage between SAEW and hydrosol ranged from 1.5-1.7%, in which E. coli was reduced by 4.50 log10 CFU/mL at an ACC of 9.94 ppm. When increasing the ACC to 14.84 ppm, E. coli was reduced by 4.51 log10 CFU/mL compared with the initial number of bacteria (8.20 log10 CFU/mL) in the control group. The number of bacteria was undetected after increasing ACC to 19.93, 25.15, and 29.88 ppm at 10 min. This study suggests that LMS hydrosol incorporated with SAEW could potentially be used as an effective sanitizer.

Antibacterial effect and mechanism of shorter ultraviolet light (222 nm) combined with slightly acidic electrolyzed water against Escherichia coli

The impact and mechanism of the combination of Slightly acidic electrolyzed water (SAEW) and shorter UV-C wavelengths at 222 nm (UV222) disinfection (SAEW + UV222) on Escherichia coli (E. coli) were evaluated. A reduction of 6.77 log CFU/mL of E. coli was observed after the combination treatment at an available chlorine concentration (ACC) of 30 mg/L for 120 s. A constructed model (R2 = 0.99) indicated the bactericidal effect of SAEW + UV222 was positive and nonlinearly correlated between time and ACC and their interactions (P < 0.05). Moreover, the SAEW + UV222 treatment required a longer time (120 s) to achieve similar bactericidal effects as the combination of SAEW and UV-C wavelengths at 254 nm treatment. Additionally, UV222 treatment (60 s) alone did not affect the intracellular ROS and ATP of E. coli. In contrast, SAEW + UV222 treatment (30 mg/L, 60 s) induces the accumulation of intracellular ROS and the reduction of ATP of E. coli and destroys the cell membranes. Our study indicates that SAEW + UV222 is a combination disinfection method with great potential.

Bactericidal Efficacy and Mechanisms of Non-Electrolytic Slightly Acidic Hypochlorous Water on Pseudomonas fragi and Pseudomonas fluorescens.

Chilled pork is frequently contaminated with Pseudomonas fragi and Pseudomonas fluorescens. In this study, the bactericidal efficacy and mechanisms of non-electrolytic slightly acidic hypochlorous water (NE-SAHW) against two strains of these two species were evaluated. The results showed that the antibacterial efficacy of NE-SAHW was positively correlated with the concentration level of NE-SAHW and negatively correlated with the initial populations of the strains. The strains of small populations were completely inhibited when provided with each level of NE-SAHW. The killed cells of P. fragi were 0.94, 1.39, 4.02, and 5.60 log10 CFU/mL, respectively, and of P. fluorescens they were 1.21, 1.52, 4.14, and 5.74 log10 CFU/mL, respectively, when the initial populations of the strains were at high levels (about 7 log10 CFU/mL). Both strains were completely killed within 12 s with the available chlorine concentration (ACC) of 50 mg/L of NE-SAHW. Morphological changes in both cells were observed by using a Scanning Electron Microscope (SEM) and it was discovered that the cell membranes were damaged, which led to the leakage of the intracellular substances, including K+, nucleic acid, and protein. In terms of the Fourier Transform Infrared Spectroscopy (FTIR) results, NE-SAHW destroyed the structures of membrane proteins and cell structure proteins, and influenced the composition of polysaccharides. The bacteria were definitely dead after treatment by NE-SAHW compared to the control according to the results of flow cytometry. These results demonstrated the potential bactericidal property of NE-SAHW when applied to the meat and other food sterilization industries.

Comprehensive evaluation of treating drinking water for laying hens using slightly acidic electrolyzed water

Slightly acidic electrolyzed water (SAEW) is well-known for its highly potent antibacterial properties and safe residue-free nature. In this study, a comprehensive evaluation was conducted on 2 disinfection methods for waterline cleaning in poultry houses: (1) continuously add SAEW into the waterline and (2) the conventional waterline disinfection method, which includes regular use of high-concentration chemical disinfectant for soaking the waterline and flushing with water. The evaluation focused on the effects of these methods on bacteria levels in laying hens' drinking water, the fecal normal rate of laying hens, egg quality, as well as the economic costs and water footprint associated with each method. The results show that the inhibition rate of the control group was 52.45% to 80.36%, which used 1500 mg/L sodium dichloroisocyanurate (DCCNa) for soaking and then flushing with water. The bacterial levels in the waterline returned to pre-treatment levels 26 h after cleaning. However, the experimental group with an available chlorine concentration (ACC) of 0.3 mg/L SAEW showed a higher inhibition rate (99.90%) than the control group (P < 0.05) and exhibited a sustained antimicrobial effect. Regarding eggshell thickness, eggshell strength, and Haugh units of the egg, there were no significant differences between the experimental and control groups. However, the experimental group had higher egg weight and darker yolk color (P < 0.05) than those of the control group. Besides, the experimental group exhibited a higher fecal normal rate and a lower water footprint than those of the control group. Hence, SAEW represents a favorable choice for disinfecting drinking water in poultry houses due to its ease of preparation, lack of residue, energy efficiency, and efficient antibacterial properties. To ensure adequate sanitation, it is recommended to incorporate SAEW with an ACC of 0.3 mg/L into the daily management of the drinking water system for laying hens.

Effects of acidic electrolyzed-oxidizing water treatment on the postharvest physiology, storability, and quality properties of navel orange fruit

Postharvest navel oranges are susceptible to fruit spoilage and quality deterioration, which restricts their storage-life and commercial values. Acidic electrolyzed-oxidizing water (AEOW) is a safe, economic and environmentally friendly postharvest treatment method that can maintain the quality of fresh products and prolong their storage life. Effects of AEOW with pH 2.5 and 75 mg/L of available chlorine concentration (ACC) on the storability and quality properties of ‘Newhall’ navel orange fruit during postharvest storage from 0 to 180 d were detected. Compared with the control group, AEOW-treated navel oranges displayed a lower respiration rate and cell membrane permeability, lower occurrence of fruit disease and weight loss, a higher commercially acceptable fruit rate, higher values of L*, b*, C as well as h°, and lower values of a* and citrus color index. Moreover, samples treated with AEOW were able to maintain higher contents of flesh carotenoid, flavonoid, and total phenolics. The AEOW treatment was conducive to maintaining higher fruit firmness and postponing the decomposition of flesh total soluble solids, total soluble sugar, sucrose sugar, reducing sugar, and vitamin C, and maintaining higher titratable acidity of navel oranges during storage. These findings corroborated that the AEOW treatment could be a means for maintaining quality attributes and improving the storability of navel oranges.

Influence of available chlorine on corrosion behaviour of low alloy marine steel in natural seawater

ABSTRACT Available chlorine is known to play a significant role in metal corrosion due to its oxidising properties. In this paper, the effect of available chlorine concentration on corrosion behaviour of the low alloy marine steel was investigated by electrochemical and immersion tests. Experimental results show that the corrosion rate of low alloy marine steel is accelerated with the increase of available chlorine concentration in seawater. The localised electrochemical dissolution of the steel is more active with the concentration of available chlorine increasing. Energy dispersive spectroscopy (EDS) was performed to understand the composition of the corrosion products that the large enrichment of Cl element occurred for the high available chlorine concentration (100 ppm) after 720 h exposure to seawater. The influence of available chlorine concentration on mechanical property of low alloy marine steel indicatesthe less impact on the tensile and yield strength of the low alloy marine steel.

Degradation of natural organic matter and disinfection byproducts formation by solar photolysis of free available chlorine

Environment disinfection effectively curbs transmission of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). However, elevated concentration of free available chlorine (FAC) in disinfectants can be discharged into surface water, generating toxic disinfection byproducts (DBPs). The impact of solar photolysis of FAC on natural organic matter (NOM) to form DBPs has not been well studied. In this work, solar photolysis of FAC was found to result in higher formation of DBPs, DBPs formation potential (DBPsFP), total organic chlorine (TOCl) and lower specific ultraviolet absorbance at 254 nm (SUVA254), compared to dark chlorination. In solar photolysis of FAC, formation of total DBPs was promoted by pH=8, but hindered by the addition of HCO3−, radical scavenger or deoxygenation, while addition of NO3−and NH4+both enhanced the formation of nitrogenous DBPs. Differences in the formation of DBPs in solar photolysis of FAC under various conditions were influenced by reactive species. The formation of trichloromethane (TCM) and haloacetic acids (HAAs) in solar photolysis of FAC positively correlated with the steady-state concentrations of ClO• and O3. The steady-state concentrations of •NO and •NH2 positively correlated with the formation of halonitromethanes (HNMs). HAAs and haloacetonitriles (HANs) mainly contributed to calculated cytotoxicity of DBPs. This study demonstrates that solar photolysis of FAC may significantly impact the formation of DBPs in surface water due to extensive use of disinfectants containing FAC during SARS-CoV-2 pandemic.

NaClO-ს მიღება NaCl-ის დაბალი კონცენტრაციის წყალხსნარების ელექტროლიზით

The work aims to develop a method for producing NaClO by electrolysis of 20–25 g/L NaCl aqueous solution under conditions other than optimal, ensuring the maintenance of competitive technical and economic indicators of this product, primarily in terms of specific electric energy consumption. NaClO produced by electrolysis of a low concentration NaCl aqueous solution is used in the process of modifying zeolite with MnO2 by indirect electrochemical oxidation, where the mediator is the redox system NaCl – NaClO. Optimal conditions for producing NaClO by electrolysis of aqueous solution of 20–25 g/L NaCl are determined: concentration of available chlorine in the solution produced by electrolysis – 2.0–2.3 g/L; Anodic current density – 200–300 A/m2 ; Electrolyte temperature – 20–250C. Under these conditions, the available chlorine yield is 74.8–82.5%, and the specific electric energy consumption is 5.12–7.61 kWh/kg, which is equal to the value of a similar characteristic obtained under optimal industrial conditions.

Effectiveness of neutral electrolyzed water in inactivating HCoV-OC43 and SARS-CoV-2 on the surfaces of plastic and the medicinal plant Centella asiatica (L.) urban

Concerns have been raised about viral contamination, including in crops due to the recent coronavirus disease 2019 pandemic. Limited evidence is available to support the use of sanitizing agents for human coronavirus-contaminated medicinal plants. Thus, we aimed to investigate the persistence of infectious human coronavirus OC43 (HCoV-OC43) as a SARS-CoV-2 surrogate in storage conditions and the capability of neutral electrolyzed water (NEW) to inactivate coronavirus, including in fresh plants such as C. asiatica. The levels of infectious HCoV-OC43 and the triterpenoid content of C. asiatica were quantified using a plaque assay and high-performance liquid chromatography, respectively. The results showed that the persistence of HCoV-OC43 on C. asiatica leaves is identical to that on inert polystyrene. When covered and kept at room temperature with high humidity (>90% RH), HCoV-OC43 can be stable on C. asiatica leaves for at least 24 h. NEW with 197 ppm of available chlorine concentration (ACC) was effective in inactivating both infectious HCoV-OC43 and SARS-CoV-2 in suspension (≥3.68 and ≥4.34 log reduction, respectively), and inactivated dried HCoV-OC43 on the surfaces of C. asiatica leaves (≥2.31 log reduction). Soaking C. asiatica leaves for 5 min in NEW with 205 ppm of ACC or water resulted in significantly higher asiaticoside levels (37.82 ± 0.29 and 35.32 ± 0.74 mg/g dry weight, respectively), compared to the unsoaked group (29.96 ± 0.78 mg/g dry weight). These findings suggest that although coronavirus-contaminated C. asiatica leaves can pose a risk of transmission, NEW could be an option for inactivation.

Sustainable sanitation: Screening methods of electrolysing parameters for a custom-built electrolysed water generator

Sanitation is a compulsory procedure in the food industry. As it involves production downtime, it imposes overhead costs. One way to obtain higher profit margins is to cut the overhead costs of sanitation. Eco-innovative cleaners and sanitisers such as electrolysed water have a high potential to reduce sanitation costs. The only ingredients of electrolysed water are salt and distilled water. Some major food industries invest in expensive commercial electrolysed water generators to produce different types of electrolysed water (acidic, alkaline, and neutral). Smaller food industries can install an electrolysed water generator independently, but they need to determine the optimum and most economical electrolysing parameters. Different electrolysed water generators employ different electrolysing parameters to produce electrolysed water with the same physical and chemical properties. Thus, in this work, electrolysing parameter screening methods are demonstrated. A laboratory-scale electrolysed water generator was used to investigate the effects of different electrolysing parameters (voltages (1–20 V), electrolysis times (1–15 min), and sodium chloride concentrations (0.05–3%)) on the physical and chemical properties (pH, oxidation-reduction potential (ORP), and available chlorine concentration (ACC)) of electrolysed water (both acidic and alkaline). These screening methods were essential to determining the range of electrolysing parameters to use for the optimisation experiments and ascertaining the generator's limit. The subsequent optimisation experiments aimed to ensure the generator could be used for a long period and that economical usage conditions were achieved. The screening experiments helped to reduce the parameter variations in these experiments and provide reliable data on electrolysed water properties. • A new custom-built electrolysed water-generating device was introduced. • Screening experiments were performed before the custom-built generator can be used. • The limit of the custom-built generator was determined. • The effect of electrolysing parameters on the EW's physicochemical was investigated. • The results were used for the optimisation experiments.

Effect of household sanitizing agents and electrolyzed water on Salmonella reduction and germination of sunflower and roselle seeds

Sprout consumption has become more popular due to a new variety of sprouts being introduced to the market. However, sprout seeds are a major source of sprout contamination and have been linked to most sprout-associated foodborne outbreaks. This study investigated Salmonella reduction in sunflower and roselle seeds using various sanitizing agents including water, water at 55 °C, sodium hypochlorite (NaOCl), diluted vinegar, acidic electrolyzed water (ACEW), and alkaline electrolyzed water (ALEW). Diluted vinegar containing 1.25% (v/v) acetic acid was the most effective treatment to inactivate Salmonella in sunflower seeds, resulting in a 3.82 log reduction after 15-min treatment. High concentrations of NaOCl (available chlorine concentration (ACC) 1692 mg/L) and ACEW (pH 2.76, oxidation-reduction potential 1093 mV, ACC 48 mg/L) had significantly lower antimicrobial activity with 3.20 and 2.39 log reduction, respectively, after 15-min treatment. Disinfecting roselle seeds for 15 min with water at 55 °C and diluted vinegar had comparable efficacy to reduce Salmonella by 2.54 and 2.48 log, respectively. There were no significant changes in Salmonella reduction among the high and low concentrations of NaOCl containing ACC 79 and 1692 mg/L, respectively, and ACEW in roselle seeds during 5–15 min of exposure time. All tested treatment solutions had no negative impact on the percentage of seed germination with over 96% and 92.56–95.89% for sunflower and roselle seeds, respectively. Conversely, the fresh weight and length of sunflower and roselle sprouts were influenced significantly by the types of sanitizing agents used for decontaminating the seeds. Collectively, our findings may contribute to the development of effective seed sanitization measure for sunflower and roselle seeds to reduce the risk of Salmonella-associated outbreaks linked to sprout consumption.

Optimizing slightly acidic electrolyzed water (SAEW) production through experiments and gene expression programming

Slightly acidic electrolyzed water (SAEW) was produced through hydrochloric acid (HCl) electrolysis in a lab-scale reactor equipped with titanium-coated anode and cathode, without a diaphragm. The effect of changes in the production parameters (voltage, feed water flow rate (FFR), acid flow rate (AFR), and acid concentration (AC) and feed water characteristics (pHf, temperature, organic matter (OM) content, and water hardness) on the SAEW properties was evaluated based on the available chlorine concentration (ACC), pH, and oxidation-reduction potential (ORP) of the final product. Moreover, a gene expression programming (GEP) model was developed using the experimental results as a predictive tool to optimize the process. The results indicated that variations in FFR, AC, AFR, and OM significantly affected the SAEW properties. In contrast, no substantial effect was observed by varying the feed water's temperature, pH, voltage, and hardness. Using tap water, the optimal conditions to produce SAEW were observed at an FFR of 6.5 L/min, pHf of 7.45, at 20 °C using 6% AC at an AFR of 9 mL/s with reactor operation at 3.8 V. The proposed GEP model showed an efficient correlation coefficient (CC) of 0.941 and 0.938, and coefficient of determination (R2) of 0.885 and 0.880, respectively, for the unseen testing data to predict the ACC and pH of the produced SAEW.

Contribution of slightly acidic electrolytic water ( SAEW ) to food safety, nutrients enrichment, and allergenicity reduction of peanut sprouts

Previous studies have confirmed that electrolyzed water had disinfection potential and enrich functional nutrients during seed germination. However, the effect of slightly acidic electrolyzed water (SAEW) on the quality and safety of peanut sprouts is poorly understood. In this study, the influence and mechanism of SAEW on the antibacterial, antioxidant capacity, and allergenicity of peanut sprouts were investigated. Although SAEW-3 with 33.85 mg/L available chlorine concentration (ACC) showed better antibacterial effect, the SAEW-2 (23.74 mg/L ACC) group has a 20% and 50% increase in phenolic acid and γ-aminobutyric acid content, respectively. Moreover, SAEW-2 induced peanut sprout has the best antioxidant capacity by eliminating free radicals and improving peroxidase activity. SAEW-2 or SAEW-3 treatment contributed to decreasing Ara h 1 and Ara h 2 content thus reduce allergenicity. Therefore, SAEW with appropriate ACC could be a promising application in food safety, nutrients enrichment, and health-improvement of peanut products. Novelty impact statement Slightly acidic electrolyzed water (SAEW) with 23.74 mg/L available chlorine concentration (ACC) has a significant positive effect on the enrichment of phenolic and γ-aminobutyric acid in germinated peanut. With the help of SAEW, the germination process can further reduce the content of Ara h 1 and Ara h 2, thereby reducing allergenicity. SAEW with appropriate ACC could be a promising application in food safety, nutrients enrichment, and health-improvement of peanut products.

Metal Contamination and Stability of Household Bleach and Specially-Formulated Sodium Hypochlorite for Endodontic Use

The aims of this in vitro study were to investigate metal contamination and short-term stability of two types of household bleach and a specially-formulated sodium hypochlorite (NaOCl) for endodontic use. The first part of the study was to compare traces of metal elements (Cu, Fe and Ni) between the two types of household bleach (Clorox and Milton) and a specially-formulated NaOCl (CanalProTM 3% NaOCl, Coltene, Whaledent)) using UV spectrophotometer. The second part of the study was to compare the available chlorine and pH of these different NaOCl formulations at different temperatures. Chemical stability of the NaOCl was assessed by measuring the amount of free available chlorine (FAC) using the iodometric titration assay at the temperature of 15, 30, 45, and 60 °C. The pH of the solutions was measured using calibrated pH meter. The results showed that Milton contained significantly higher concentration of Cu, Fe and Ni compared with the other formulations (P &lt; 0.001). Concentrations of Fe detected in Clorox and CanalPro were higher than in the control, distilled water (P &lt; 0.05). In all NaOCl samples, the concentration of available chlorine increased with temperature. Concomitantly, there was a significant decrease in pH with increasing temperature (P &lt; 0.001) with all the NaOCl formulations. In conclusion, traces of metal remnants could be observed in all the NaOCl formulations, especially in Milton. Heating the NaOCl increases the FAC and decreases its pH.

Rapid in vitro virucidal activity of slightly acidic hypochlorous acid water toward aerosolized coronavirus in simulated human-dispersed droplets

The virucidal activities were evaluated by spraying slightly acidic hypochlorous acid waters (SAHWs) containing various concentrations of free available chlorine - 100, 200, 300 and 500 ppm (SAHW-100, -200, -300 and -500, respectively) - toward aerosol of an avian coronavirus (infectious bronchitis virus: IBV). The viral solution was supplemented with 0.5% fetal bovine serum (FBS) to simulate normal human droplets generated by sneezing or coughing in a real-life scenario. The virus containing 0.5% FBS was sprayed and exposed to SAHWs for a few seconds in a closed chamber, before reaching the air sampler. The results showed that IBV exposed to SAHW-100 and -200 for a few seconds decreased by 0.21 log10 and 0.80 log10, respectively, compared to the pre-exposed samples to SAHWs as controls. On the other hand, reductions of 1.16 log10 and 1.67 log10 were achieved following the exposure to SAHW-300 and -500, respectively, within a few seconds. These results suggest that SAHWs have rapid in vitro virucidal activity toward aerosolized IBV. The findings obtained for IBV might basically be applicable in relation to SARS-CoV-2, given the resemblance between the two viruses. To prevent human-to-human transmissions by aerosols, the inactivation of viruses in the air by exposure to SAHWs for a few seconds seems to be an effective way.

Antibacterial activity and mechanism of slightly acidic electrolyzed water against Shewanella putrefaciens and Staphylococcus saprophytic

The purpose of this study was to investigate the antimicrobial effect and mechanism of slightly acidic electrolyzed water (SAEW) against Shewanella putrefaciens (S. putrefaciens) and Staphylococcus saprophytic (S. saprophyticus). The results showed that SAEW exhibited strong antimicrobial activity against tested bacteria, which was positively correlated to the available chlorine concentration (ACC) of SAEW. The mortality rate of S. putrefaciens and S. saprophyticus was up to 96% and 85%, respectively, when the ACC of SAEW was 60.0 mg/L. The results of scanning electron microscopy (SEM) showed that the cell morphology and structure were destroyed by SAEW. Besides, the results of confocal laser scanning microscopy (CLSM), leakage of DNA and protein provided evidence that SAEW induced membrane permeabilization in cells. Compared with the control, the intracellular reactive oxygen species (ROS) generated by SAEW was strengthened significantly with the increase of ACC, and the cells were injured to death accordingly.

Effect of electrolyzed water and carbon dioxide microbubbles on removal of diazinon and diazoxon

AbstractEffect of electrolyzed water (EW) produced from sodium chloride solution in a single vessel and carbon dioxide microbubbles (CO2MB) on decomposition of diazinon and its oxidized product, diazoxon, was investigated. Furthermore, these removal by the EW with CO2MB from broccoli‐attached diazinon was examined. Diazinon was oxidized to diazoxon by EW, and the oxidative effect increased with increasing EW concentration from 0.1 to 0.6 mol L−1 or electrolyzing time from 1 to 10 min. However, EW concentration more than 0.2 mol L−1 was required to reduce diazoxon. The effect of EW on the decomposition of diazoxon increased with increasing EW concentration, electrolyzing time or reaction time from 10 to 60 min but decreased by generating CO2MB. Furthermore, diazinon concentration in broccoli was significantly decreased by treatment with deionized water or EW for 10 min, and the removal effect was continued by generating CO2MB in EW until 60 min. The diazoxon concentration in broccoli treated by EW decreased after increased up to 30 min, and the removal effect was increased by generating CO2MB. Also, the pH and available chlorine concentration (ACC) of the EW increased with increasing EW concentration or electrolyzing time but decreased and almost unchanged by generating CO2MB, respectively. Therefore, it was revealed that EW had a decomposition effect on diazinon and diazoxon and that CO2MB promoted the effect of EW on the removal of these pesticides in broccoli. Additionally, the decomposition effect of EW on diazinon and diazoxon was suggested to be influenced by high pH and ACC.Practical ApplicationThe EW produced from NaCl solution in a single vessel is a safer technique easy to be used than that from HCl. In addition, CO2MB has no harmful effects on the human body. This study demonstrated that the EW was effective for decomposing diazinon, an organophosphorus insecticide, and diazoxon, its oxidized product, and that the removal of these pesticides in broccoli by the EW could be more effectively achieved by generating CO2MB. Therefore, the use of EW with CO2MB can be expected to remove pesticides from fruits and vegetables at food factory.