Ppm Sodium Hypochlorite Research Articles

Efficacy of Virucidal Treatments against Poliovirus Type 1 Deposited on Stainless-Steel Carriers.

Safe containment of infectious poliovirus (PV) within Poliovirus-Essential Facilities (PEFs) will require the implementation of reliable PV-inactivation approaches for decontaminating work surfaces. Such approaches should be demonstrated empirically to display adequate efficacy at the use temperature, and the contact times required should be characterized to ensure efficacy. Such efficacy is judged by the ability of the inactivation approach to completely inactivate any PV deposited, with the demonstrated total log10 reduction in PV titer being as high as empirically achievable. We screened several approaches for their efficacy in inactivating wild-type PV type 1 Chat strain experimentally deposited on stainless-steel carriers at room temperature. On the basis of the results, we selected two approaches (5000 ppm sodium hypochlorite in water and 95% v/v ethanol in water) for further characterization for repeatability of efficacy (log10 reduction in PV titer) and time kinetics of inactivation. We now report that both PV-inactivation approaches, which should be readily available to all PEF laboratories globally, fulfill the expectations expressed above, with 5000 ppm sodium hypochlorite reproducibly causing ≥5.38 log10 inactivation and 95% ethanol reproducibly causing ≥4.46 log10 inactivation of PV on stainless-steel surfaces within a 5 min contact time at room temperature.

Impact of membrane characteristics and chemical ageing on algal protein fouling behaviour of ultrafiltration membranes

Membrane characteristics can exacerbate the prevailing challenges associated with membrane fouling in industry. However, the combined impact of deliberate membrane modifications and the unavoidable effects of chemical ageing on fouling behaviour is still not well understood. In this study, three polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes with different pore size and surface roughness were selected and subject to chemical ageing with 5000 ppm sodium hypochlorite (NaOCl) at pH 10.5, selected to simulate accelerated ageing conditions. The impact of NaOCl on membrane characteristics was assessed for exposure times from 1.2 x 105 to 25.2 x 105 ppm·h using scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, contact angle, and clean water resistance analysis. The fouling behaviour of each pristine and aged membrane was compared using 10 mg C·L−1 dissolved organic carbon algal protein feed containing 18 % biopolymeric compounds. The membrane with intermediate pore size presented lower overall filtration resistance compared to the membrane with smaller pores that developed rapid foulant cake layers. It also displayed less susceptibility to fouling via pore blocking mechanisms compared to membranes with larger pores where greater surface area available in pore walls leads to higher foulant adhesion.

Surface sanitation as a recommended treatment for preventing fungal infection and extending the shelf life of watermelon

Watermelon ranks fifth in Malaysian fruit production after coconut, durian, banana and pineapple. Its export value has increased significantly at 6.2%, from 60 thousand MT (2018) to 64 thousand MT. Losses happen throughout the supply chain, especially during the production and logistic process. The watermelon supply chain involves one- or twotier supply chain, which comprises movement from producers, wholesalers, retailers and final users. A preliminary survey had been conducted to estimate the postharvest losses percentage along the supply chain. The total postharvest loss for watermelon in Malaysia was high at 33%, with losses at the collection centre accumulating the highest percentage (56%). This high loss needs to be addressed as it will affect the farmers’ income and lead to an increase in food waste in the agriculture sector. A study on sanitation treatment to reduce fungal infection and extend the shelf life of watermelon was conducted. Sanitation treatments consisted of dipping the watermelon fruit in water treated with 250 ppm sodium hypochlorite for 30 seconds (Treatment 1) and spraying the peduncle with 250 ppm propiconazole fungicide (Treatment 2). Unsanitized fruit was set as control (Treatment 3). Results showed that sanitized watermelon samples (dipped in sodium hypochlorite or sprayed with propiconazole) rated acceptable until four weeks of storage at the ambient temperature of 27°C. Unsanitized fruit was infected with mould and thus rated as poor. Biochemical properties were not affected by sanitation treatment. In conclusion, sanitation using 250 ppm sodium hypochlorite or 250 ppm propiconazole helps slow down the fungal infection and extends the shelf life of watermelon fruit up to four weeks. This sanitation treatment is recommended to be included in the watermelon postharvest handling procedure to maintain good quality, reduce losses and expand the market for domestic and export.

Dual functionalization of polyamide reverse osmosis thin film composite membrane for improving chlorine resistance

Contemporary high-efficiency polyamide (PA) membranes are constructed using aliphatic or aromatic amines combined with acyl chlorides. Nevertheless, the aromatic rings attached to the N–H group within the amide linkages are vulnerable to degradation by chlorine. The surface of a PA reverse osmosis (RO) membrane was altered in this work through the dual functionalization of tannic acid (TA) and silver nanoparticles (Ag NPs) to improve separation performance, chlorine resistance, and anti-bacterial capabilities of membranes. This study provides an insight in the role and synergistic effects of TA and Ag NPs for enhancing the chlorine resistance of the modified TFC membranes. The outcome indicated that the RO-TA/Ag modified membrane exhibited the maximum rejection of 98.31%, slightly surpassing the pristine RO membrane, which had a rejection rate of 96.52%. The RO-TA/Ag modified membrane also shown improved chlorine tolerance against 500 ppm sodium hypochlorite solution (NaClO), as evidenced by X-ray photoelectron spectroscopy (XPS) measurement which revealed reduced chlorine content in contrast to pristine RO and RO-TA membrane. The RO-TA/Ag membrane exhibited the largest inhibitory zone for both Gram-positive, S. aureus and Gram-negative, E. coli bacteria. The synergistic effects of the dual functionalization of TA and Ag NPs which render the modified membrane with high anti-chlorine and anti-bacterial capabilities are discussed.

Neutralization of ricin toxin on building interior surfaces using liquid decontaminants.

Ricin is a highly toxic protein, capable of inhibiting protein synthesis within cells, and is produced from the beans of the Ricinus communis (castor bean) plant. Numerous recent incidents involving ricin have occurred, many in the form of mailed letters resulting in both building and mail sorting facility contamination. The goal of this study was to assess the decontamination efficacy of several commercial off-the-shelf (COTS) cleaners and decontaminants (solutions of sodium hypochlorite [bleach], quaternary ammonium, sodium percarbonate, peracetic acid, and hydrogen peroxide) against a crude preparation of ricin toxin. The ricin was inoculated onto four common building materials (pine wood, drywall joint tape, countertop laminate, and industrial carpet), and the decontaminants were applied to the test coupons using a handheld sprayer. Decontamination efficacy was quantified using an in-vitro cytotoxicity assay to measure the quantity of bioactive ricin toxin extracted from test coupons as compared to the corresponding positive controls (not sprayed with decontaminant). Results showed that decontamination efficacy varied by decontaminant and substrate material, and that efficacy generally improved as the number of spray applications or contact time increased. The solutions of 0.45% peracetic acid and the 20,000-parts per million (ppm) sodium hypochlorite provided the overall best decontamination efficacy. The 0.45% peracetic acid solution achieved 97.8 to 99.8% reduction with a 30-min contact time.

Carbapenem-resistant Acinetobacter baumannii Outbreak in a COVID-19 Isolation Ward and Successful Outbreak Control with Infection Control Measures.

Even amid the coronavirus disease-19 (COVID-19) pandemic, the spread of multidrug-resistant bacteria and infection control are still important tasks. After recognizing the carbapenem-resistant Acinetobacter baumannii (CRAB) outbreak that occurred in the isolation room for COVID-19, we would like to introduce what infection control measures were implemented to eradicate it. All COVID-19 patients with CRAB in any specimen admitted to the COVID-19 isolation ward of the tertiary hospital in Korea from October to November 2021 were analyzed. During the outbreak, 23 patients with COVID-19 and CRAB infections were identified. The index case was an 85-year-old female referred from a long-term care facility. CRAB was identified in sputum culture in most patients (91.3%). The CRAB outbreak occurred mainly in the rooms around the index case. Environmental cultures on the floor, air inlet, air outlet, and window frame of the rooms were performed. The antimicrobial resistance patterns of CRAB from patients and the environment were identical; whole-genome sequencing analyses revealed isolated clonality. Infection control measures with enhanced environmental cleaning using 1,000 ppm sodium hypochlorite and phenolic compounds, enhanced hand hygiene, additional education, and mandatory additional gowning and gloving of COVID-19 personal protective equipment (PPE) were applied on 29 October. No CRAB infection cases occurred from 2 November for two weeks. In addition to applying PPE and COVID-19 precautions in COVID-19 isolation wards, adhering to strict contact precautions along with environmental control can help prevent the spread of multidrug-resistant bacteria.

Investigation on the inactivation effect and mechanism of Listeria monocytogenes in fresh-cut cucumber during storage by ultrasound combined with sodium hypochlorite

Fresh agricultural products are frequently contaminated with Listeria monocytogenes (L. monocytogenes), which threatens consumer health. The mechanism of the inhibitory effect of ultrasound and sodium hypochlorite (US-NaClO) on L. monocytogenes on fresh-cut cucumber remains poorly understood. Therefore, the bactericidal ability and mechanism of US-NaClO treatment on L. monocytogenes were studied on fresh-cut cucumber during storage using various approaches such as determination of intracellular material leakage, scanning electron microscopy, flow cytometry, and expression analysis of virulence genes. The results showed that the number of L. monocytogenes on fresh-cut cucumber was significantly reduced after ultrasound treatment for 5 min in combined with 75 ppm sodium hypochlorite treatment(P < 0.05). The US–NaClO treatment affected cell morphology, impaired cell membrane integrity, increased cell membrane permeability, and reduced the concentration of K+, inorganic phosphate, ATP, proteins, and DNA in bacterial cells, leading to the inactivation of microorganisms. In addition, the US–NaClO treatment downregulated expression of the virulence genes actA, hly, inlA, mpl, pclA, and plcB, thus decreasing the pathogenicity of bacteria. It can avoid contamination by pathogenic bacteria during the production of fresh-cut cucumber, while providing safety assurance for production.

Comparison of sanitization efficacy of sodium hypochlorite and peroxyacetic acid used as disinfectants in poultry food processing plants

This study, we aimed to evaluate the in situ disinfection efficacy of peroxyacetic acid (PAA) and sodium hypochlorite (SH) against pathogens (Escherichia coli, Staphylococcus aureus, Salmonella Typhimurium, and Listeria monocytogenes in suspension, and food contact surfaces of steel and utensil. In the clean and contaminated conditions, as the concentrations of PAA and SH increased (0–200 ppm) for 1 min and 5 min, the viable count of pathogenic bacteria reduced. In particular, more than 7 log cycle reductions in the pathogen population were observed using 200 ppm PAA and 100 ppm SH, except for S. aureus in the latter. Four pathogenic bacteria spiked (5–6 log/mL), each on the surface of the main processing machine (stainless steel, n = 36), displayed over 6 log reduction after treatment with 100 ppm PAA for 5 min, which was more effective than SH treatment at similar conditions. To compare the sterilization effect, swab sampling (n = 27) before and after working with poultry on cutting boards, knives, and worktable was performed. E. coli, coliforms, and total bacteria were considerably reduced using 100 ppm of both PAA and SH. After five different treatment concentrations (0–200 ppm) at 4 °C for seven days, chicken breasts treated with 200 ppm PAA exhibited a significant (P < 0.05) inhibitory effect on the total bacteria (1.29 log10) and coliform group organisms (1.10 log10) populations compared with the control chicken breast. Overall, PAA treatment had an effective antimicrobial activity in fresh poultry samples. The microbiological safety of poultry is an important public health concern worldwide, thus, the use of PAA as a disinfectant will greatly contribute to the improvement of poultry microbial safety.

Highly selective and permeable β-cyclodextrin based polyester nanofiltration membranes maintaining good chlorine resistance

Possessing high chlorine resistance is an important consideration for membranes to be applied for water treatment. In this study, the superior chlorine resistant β-cyclodextrin (β-CD) based polyester membranes were developed via interfacial polymerization (IP) with the β-CD and glycerol or mannitol as the aqueous phase monomers. By adjusting the compositions of the aqueous phase, the pore size and distribution of the resultant membranes were accurately controlled, thus improving the separation efficiency of the membranes. The optimized membrane (β-CD/Ma3) had the higher water flux (60.4 L‧m-2‧h-1 at 2.0 bar) and Na2SO4 retention (95.6%). After immersed in 10 ppm sodium hypochlorite (NaClO) solution for 360 h, the membrane performance in terms of water flux and salt retention was almost unaltered, mirroring a good long-term stability. In another test, the Na2SO4 retention of membrane remained at 91.7%, which was only 4.1% lower than the original value, after exposure to a high concentrated NaClO solution (2000 ppm) for 72 h. Fouling cycling test was also performed, and the flux was maintained as high as 97.2% of the original value after examination of three cycles. All these observations clearly indicate that the optimized membrane has outstanding chlorine resistance and superior antifouling property.

Control of water activity and thermal processing temperature to preserve seed viability and vigor while effectively killing Salmonella

In the past three decades, numerous outbreaks linked to seed sprouts have occurred in the United States and many other countries. In most of the sprout-related outbreaks, seeds were identified as the most likely source of contamination. The goal of this study was to develop a heat treatment that could effectively inactivate Salmonella on seeds while preserving their viability and vigor. Mung bean, red clover, and radish seeds were inoculated with a cocktail of 4 Salmonella strains and conditioned to aw of 0.10–0.33. The inoculated seeds were heated at 71.0, 76.6, and 80.6 °C for up to 160 h. Thermal inactivation of Salmonella was greatly improved by increasing seeds' aw. To achieve >5 log reductions of Salmonella on mung bean seeds at 76.6 °C, increasing aw from 0.20 to 0.33 reduced the heat treatment time by 18 h. However, this increase in aw made them less tolerant to thermal treatment; resulting in a 35.1% reduction in sprout yield ratio. Although increasing heating temperature from 71.0 to 80.6 °C improved Salmonella inactivation efficiency, it drastically reduced mung bean seeds’ survival. The aw of 0.2 and heating temperature of 71.0 °C were identified as the optimum processing conditions for mung bean seeds. Heat treatment using these optimum conditions for 40 and 50 h resulted in 4.5 and 5.1 log reductions of Salmonella and sprout yield ratios of 100.8% and 98.4%, respectively. However, those optimum processing conditions did not result in satisfactory sprout yields when they were applied to red clover and radish seeds. A wash treatment of mung bean, red clover, and radish seeds with 20,000 ppm of sodium hypochlorite, as recommended by a former FDA guideline, was much less effective for seeds decontamination than the heat treatment, resulting in Salmonella population reductions ranged from 1.3 to 1.5 logs. Chlorine wash also negatively affected seed viability, reducing the sprout yield ratio by up to 35%. Compared to the chlorine wash, the heat treatment developed in this study achieved much better inactivation of Salmonella and better preservation of seed viability, especially for mung bean seeds.

Effect of Citrus aurantium juice as a disinfecting agent on quality and bacterial communities of striped catfish steaks stored at -20 °C.

Sodium hypochlorite is generally used as a disinfectant in washing of freshwater fishes where the safety aspect of health is of concern. Although plant-based essential oils and synthetic chemical agents have been applied, they might contain toxic substances, are expensive and can cause undesirable quality. This research aims to fill the knowledge gap necessary to validate Citrus aurantium juice as a disinfecting agent for preserving striped catfish steaks at -20 °C for 28 days. Fifty (50) ppm sodium hypochlorite was used as a commercial disinfectant (control). The results showed that a negative color characteristic (higher a* and increased b*) was found in the control but not in striped catfish steaks immersed in C. aurantium juice (TM) on days 14 and 28. No significant differences were found in the peroxide value among the treatments on days 14 and 28 (P > 0.05). A lower accumulation of trichloroacetic acid soluble peptides was detected in TM but not in control, while total volatile basic nitrogen of all treatments was up to standard of fish quality during storage. Contrastingly, the total viable count of both treatments increased to >7.0 log CFU/g on day 28 which did not meet the edible limit of standard for freshwater fishes. The spoilage microbial community was observed on days 0 and 28 of storage which showed a decrease in relative abundance of Acinetobacter, Pseudomonas, Brochothrix, Lactococcus, Carnobacterium, Psychrobacter, and Vagococcus as found in TM on day 28, when compared to the control. Thus, these results implied that C. aurantium juice could replace sodium hypochlorite as an alternative disinfecting agent to control the microbiological spoilage and physico-chemical quality of striped catfish steaks.

Construction and Chlorine Resistance of Thiophene-Poly(ethyleneimine)-Based Dual-Functional Nanofiltration Membranes.

The demand to improve the chlorine resistance of polyamide (PA) membranes is escalated with greater amounts of chlorine-containing disinfectant being used in global water treatment during the COVID-19 pandemic. In this work, we designed thiophene-functionalized poly(ethyleneimine) (TPEI) materials first and grafted them onto a conventional PA membrane to develop novel nanofiltration membranes (PEI-M, TPEI-1-M, TPEI-2-M). These membranes have dual-functionalized selective surfaces covered by hydrophilic amino groups and electron-rich thiophene moieties, which endow these membranes with superior chlorine resistance and improved separation performance. The modified membranes increase the rejection of MgCl2 from 86.5% of the nascent PA membrane (PA-M) to higher than 93.0% without sacrificing the membrane water permeability. More stable separation performance is achieved with all of the as-prepared membranes than PA-M after exposure to a 2000 ppm sodium hypochlorite solution. TPEI-2-M outperforms other membranes after being treated in a chlorination intensity of 16,000 ppm·h with the smallest flux loss and the highest MgCl2 rejection. This is mainly ascribed to the highest amount of amino and thiophene moieties on the TPEI-2-M surface. This study provides an effective protocol for developing novel PA-based nanofiltration membranes while demonstrating its superiority over current technologies with exceptional separation performance and antichlorine ability.

Decontamination of high-touch environmental surfaces (HITES) by wiping: quantitative assessment of a carrier platform simulating pathogen removal, inactivation and transfer in the field.

We report here a carrier platform (Teflon; 30.0×60.0×0.9 cm) and a carrier retrieval device to assess pathogen decontamination of high-touch environmental surfaces (HITES) by wiping. Each one of the nine metallic disks (1 cm diameter and 0.7 mm thick) received 10 μL of the microbial suspension in a soil load, the inocula dried and the platform then wiped with a piece of fabric presoaked in a control or disinfectant fluid; the used wipe was immediately applied on a second platform with sterile disks to assess microbial transfer. Each test and control disk from a given platform was separately and simultaneously retrieved into 10 mL of an eluent/neutralizer for assays at the end of the contact time (total of 5 min, starting from the beginning of the wiping). Staphylococcus aureus and Acinetobacter baumannii were used as representative HITES-borne pathogens. The wipes tested separately contained 0.26% of a quaternary ammonium compound (Product A), and 250 ppm sodium hypochlorite at neutral pH (Product B). The control fabric (Product C) was dampened with a buffer containing a detergent. Product A achieved a>4 log10 (>99.99%) reduction in the viability of the bacteria on wiping with a barely detectable level of transfer of CFUs to clean disks. Product B achieved a>2 log10 (>99.00%) reduction in the viability of the test microbes while transferring a higher level of CFUs as compared to Product A. With Product C, there was a<1 log10 (<86.2%) reduction in the viability of the test microbes while transferring>1% of the contamination.

Preparation of Chemically Resistant Cellulose Benzoate Hollow Fiber Membrane via Thermally Induced Phase Separation Method.

For the first time, we have successfully fabricated microfiltration (MF) hollow fiber membranes by the thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS) methods using cellulose acetate benzoate (CBzOH), which is a cellulose derivative with considerable chemical resistance. To obtain an appropriate CBzOH TIPS membrane, a comprehensive solvent screening was performed to choose the appropriate solvent to obtain a membrane with a porous structure. In parallel, the CBzOH membrane was prepared by the NIPS method to compare and evaluate the effect of membrane structure using the same polymer material. Prepared CBzOH membrane by TIPS method showed high porosity, pore size around 100 nm or larger and high pure water permeability (PWP) with slightly low rection performance compared to that by NIPS. On the contrary, CBzOH membranes prepared with the NIPS method showed three times lower PWP with higher rejection. The chemical resistance of the prepared CBzOH membranes was compared with that of cellulose triacetate (CTA) hollow fiber membrane, which is a typical cellulose derivative as a control membrane, using a 2000 ppm sodium hypochlorite (NaClO) solution. CBzOH membranes prepared with TIPS and NIPS methods showed considerable resistance against the NaClO solution regardless of the membrane structure, porosity and pore size. On the other hand, when the CTA membrane, as the control membrane, was subjected to the NaClO solution, membrane mechanical strength sharply decreased over the exposure time to NaClO. It is interesting that although the CBzOH TIPS membrane showed three times higher pure water permeability than other membranes with slightly lower rejection and considerably higher NaClO resistance, the mechanical strength of this membrane is more than two times higher than other membranes. While CBzOH samples showed no change in chemical structure and contact angle, CTA showed considerable change in chemical structure and a sharp decrease in contact angle after treatment with NaClO. Thus, CBzOH TIPS hollow fiber membrane is noticeably interesting considering membrane performance in terms of filtration performance, mechanical strength and chemical resistance on the cost of slightly losing rejection performance.

Stress Response Mechanisms of Salmonella Enteritidis to Sodium Hypochlorite at the Proteomic Level.

Salmonella Enteritidis (S. Enteritidis) can adapt to sublethal sodium hypochlorite conditions, which subsequently triggers stress resistance mechanisms in this pathogen. Hence, the current work aimed to reveal the underlying stress adaptation mechanisms in S. Enteritidis by phenotypic, proteomic, and physiological analyses. It was found that 130 ppm sodium hypochlorite resulted in a moderate inhibitory effect on bacterial growth and an increased accumulation of intracellular reactive oxygen species. In response to this sublethal treatment, a total of 492 proteins in S. Enteritidis showed significant differential abundance (p < 0.05; fold change >2.0 or <0.5), including 225 more abundant proteins and 267 less abundant proteins, as revealed by the tandem-mass-tags-based quantitative proteomics technology. Functional characterization further revealed that proteins related to flagellar assembly, two-component system, and phosphotransferase system were in less abundance, while those associated with ABC transporters were generally in more abundance. Specifically, the repression of flagellar-assembly-related proteins led to diminished swimming motility, which served as a potential energy conservation strategy. Moreover, altered abundance of lipid-metabolism-related proteins resulted in reduced cell membrane fluidity, which provided a survival advantage to S. Enteritidis. Taken together, these results indicate that S. Enteritidis employs multiple adaptation pathways to cope with sodium hypochlorite stress.

Stability and inactivation of SARS-CoV-2 on food contact surfaces

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected more than 269 million people and killed more than 5.3 million people worldwide. Although fomite transmission of SARS-CoV-2 has been continuously reported, few studies have been conducted on food contact surfaces. Therefore, this study aimed to investigate the viability of coronaviruses on food contact surfaces and to remove SARS-CoV-2 contaminated on food contact surfaces with disinfectants. At 20 °C, SARS-CoV-2 was inactivated within 48 h on all food contact surfaces. At 4 °C, it was inactivated at 48 h on kraft paper and 96 h on parchment paper, but it was viable up to 5 days in low-density polyethylene (LDPE). At −20 °C, SARS-CoV-2 did not decrease by even 1 log on all food contact surfaces until 5 days. Treatment with 70% ethanol or 1000 ppm sodium hypochlorite for 5 min was sufficient to completely remove SARS-CoV-2 from 6 food contact surfaces. Similarly, UV-C irradiation at 60 mJ/cm2 eliminated SARS-CoV-2 contaminated on food contact surfaces. Also, the wiping test showed that even wiping an area contaminated with SARS-CoV-2 with a cloth moistened with 70% ethanol or 1000 ppm sodium hypochlorite, it took 5 min to inactivate the virus. Our findings suggested that SARS-CoV-2 contaminated on food contact surfaces in local retail may be viable enough to be transported home. However, if the type and method of use of the disinfectant suggested in this study are followed, it is possible to sufficiently control the fomite transmission of SARS-CoV-2 through food contact surfaces at home.

Inactivation of human norovirus by chlorous acid water, a novel chlorine-based disinfectant

IntroductionHuman norovirus (HuNoV) is a leading cause of infectious gastroenteritis. Since HuNoV shows resistance to alcohol, chlorine-based sanitizers are applied to decontaminate the virus on environmental surfaces. Chlorous acid water (CA) has been recently approved as a novel chlorine-based disinfectant categorized as a Type 2 OTC medicine in Japan. In this study, we aimed to evaluate the capability of CA to inactivate HuNoV. MethodsHuNoV (genogroups GII.2 and GII.4) was exposed to the test disinfectants including CA and sodium hypochlorite (NaClO), and the residual RNA copy was measured by reverse transcription quantitative PCR (RT-qPCR) after pretreatment with RNase. In addition, the log10 reduction of HuNoV RNA copy number by CA and NaClO was compared in the presence of bovine serum albumin (BSA), sheep red blood cells (SRBC), polypeptone, meat extract or amino acids to evaluate the stability of these disinfectants under organic-matter-rich conditions. ResultsIn the absence of organic substances, CA with 200 ppm free available chlorine provided >3.0 log10 reduction in the HuNoV RNA copy number within 5 min. Even under high organic matter load (0.3% each of BSA and SRBC or 0.5% polypeptone), 200 ppm CA achieved >3.0 log10 reduction in HuNoV RNA copy number while less than 1.0 log10 reduction was observed with 1,000 ppm sodium hypochlorite (NaClO) in the presence of 0.5% polypeptone. CA reacted with only cysteine, histidine and glutathione while NaClO reacted with all of the amino acids tested. ConclusionsCA is an effective disinfectant to inactivate HuNoV under organic-matter-rich conditions.

Chlorine dioxide is a more potent antiviral agent against SARS-CoV-2 than sodium hypochlorite

BackgroundA new coronavirus (SARS-CoV-2) abruptly emerged in Wuhan, China, in 2019 and rapidly spread globally to cause the COVID-19 pandemic.AimTo examine the anti-SARS-CoV-2 activity of the potent disinfectant Cleverin, the major disinfecting component of which is chlorine dioxide (ClO2); and to compare the results with that of sodium hypochlorite in the presence or absence of 0.5% or 1.0% foetal bovine serum (FBS).MethodsConcentrated SARS-CoV-2 viruses were treated with various concentrations of ClO2 and sodium hypochlorite and 50% tissue culture infective dose was calcurated to evaluate the antiviral activity of each chemical.FindingsWhen SARS-CoV-2 viruses were treated with 0.8 ppm ClO2 or sodium hypochlorite, viral titre was decreased only by 1 log10 TCID50/mL in 3 min. However, the viral titre was decreased by more than 4 log10 TCID50/mL when treated with 80 ppm of each chemical for 10 s regardless of presence or absence of FBS. It should be emphasized that treatment with 24 ppm of ClO2 inactivated more than 99.99% SARS-CoV-2 within 10 s or 99.99% SARS-CoV-2 in 1 min in the presence of 0.5% or 1.0% FBS, respectively. By contrast, 24 ppm of sodium hypochlorite inactivated only 99% or 90% SARS-CoV-2 in 3 min under similar conditions. Notably, except for ClO2, the other components of Cleverin such as sodium chlorite, decaglycerol monolaurate, and silicone showed no significant antiviral activity.ConclusionAltogether, the results strongly suggest that although ClO2 and sodium hypochlorite are strong antiviral agents in absence of organic matter but in presence of organic matter, ClO2 is a more potent antiviral agent against SARS-CoV-2 than sodium hypochlorite.

Evaluation of the influence of UV radiation and sodium hypochlorite on the shelf life of strawberries

It is common to combine methods to increase the shelf life of a raw material or product. In this study, we sought to understand the relationship between ultraviolet (UV) radiation and sodium hypochlorite (NaOCl) in attenuating the proliferation of fungus and its deteriorating effect on strawberries. The UV light intensities of 125, 250 and 400 Watts (W) and sodium hypochlorite were tested in concentrations 0.5, 1.0 and 1.5 ppm. The strawberries were sprayed with sodium hypochlorite solutions and then kept for 1 minute in UV light chambers, to then be stored in transparent sealed plastic containers. The strawberry samples with the longest life were those that were sprayed with 0.5 and 1.0 ppm sodium hypochlorite solution combined with exposure to 125 W UV light. These samples had a shelf-life extension of about five days compared to strawberries without any kind of treatment. Thus, it is possible to state that this combination is efficient in cleaning the fruit without causing damage.

Self‐doped sulfonated polyaniline ultrafiltration membranes with enhanced chlorine resistance and antifouling properties

AbstractMembranes heavily rely on chlorination to diminish (bio)fouling, but chlorination can also lead to membrane degradation. We developed sulfonated polyaniline (S‐PANI) ultrafiltration (UF) membranes with improved chlorine resistance and intrinsic antifouling properties. The S‐PANI membranes were synthesized through Non‐solvent Induced Phase Separation (NIPS). Membrane performance was evaluated under harsh chlorine conditions (250 ppm sodium hypochlorite for 3 days under different pH conditions). The S‐PANI membranes showed improved chlorine resistance including a stable performance without changes in model foulant BSA rejection. In contrast, PANI membranes suffered critical structural damage with complete leakage and commercial PES membranes showed a 76% increase in pure water flux and a noticeable change in BSA rejection. Small changes in S‐PANI membrane performance could be linked to membrane structural changes with pH, as confirmed by SEM, IR spectroscopy, and contact angle measurements. Additionally, the S‐PANI membranes showed better antifouling properties with a high flux recovery ratio in comparison to PANI membranes using alginic acid, humic acid, and BSA model foulants. Chemical cleaning by sodium hypochlorite re‐instated the transport properties to its initial condition. Overall, the developed S‐PANI membranes have a high chlorine tolerance and enhanced antifouling properties making them promising for a range of UF membrane applications.