Acidic Electrolyzed Water Research Articles

The effect of various denture cleansers on the physical and mechanical properties of CAD/CAM and heat-polymerized denture base materials: an in vitro study.

To investigate the effects of denture cleansers on the various properties of CAD/CAM and heat-polymerized polymethyl methacrylate (PMMA). Two different brands of heat-polymerized and two of milled PMMA were fabricated (n = 50), in total 200. Each group was randomly divided into five subgroups (n = 10): control groups (D1) kept in distilled water, cleaning tablets (D2, D3), neutral (D4) and acidic electrolyzed acid water (EAW) (D5). Surface roughness, hardness and flexural strength values were evaluated. Data were statistically analyzed with two-way ANOVA and Tukey post hoc test for comparison (p<0.05). The milled group showed significantly lower surface roughness, greater surface hardness, and higher flexural strength values than heat polymerized denture bases (p<0.05). The denture cleansers had no significant effect on the surface roughness values of the milled specimens (p>0.05), whereas the specimens in the heat-polymerized groups and treated with D5 showed greater surface roughness values compared with the other cleaning agents (p > 0.05). The denture cleansers had no significant effect on surface hardness and flexural strength of heat polymerize groups (p > 0.05). However, D2, D3 and D5 cleaning agent decreased the hardness values of the milled group (p<0.05) and D5 cleaning agent decreased the flexural strength of the milled group (p<0.05). It was observed that the applied denture cleansers affected the surface roughness, surface hardness, and flexural strength values of both denture bases but within a clinically acceptable value. CAD/CAM denture bases showed significantly higher physical and mechanical properties than to heat-polymerized base materials. Although the applied neutral EAW cleaners give desired results for denture bases, clinical studies are needed for biological compatibility.

Isolation and Identification of Postharvest Rot Pathogens in Citrus × tangelo and Their Potential Inhibition with Acidic Electrolyzed Water.

This study focused on the identification of rot-causing fungi in Citrus × tangelo (tangelo) with a particular emphasis on investigating the inhibitory effects of acidic electrolyzed water on the identified pathogens. The dominant strains responsible for postharvest decay were isolated from infected tangelo fruits and characterized through morphological observation, molecular identification, and pathogenicity detection. Two strains were isolated from postharvest diseased tangelo fruits, cultured and morphologically characterized, and had their gene fragments amplified using primers ITS1 and ITS4. The results revealed the rDNA-ITS sequence of two dominant pathogens were 100% homologous with those of Penicillium citrinum and Aspergillus sydowii. These isolated fungi were confirmed to induce tangelo disease, and subsequent re-isolation validated their consistency with the inoculum. Antifungal tests demonstrated that acidic electrolyzed water (AEW) exhibited a potent inhibitory effect on P. citrinum and A. sydowii, with EC50 values of 85.4μg/mL and 60.12μg/mL, respectively. The inhibition zones of 150μg/mL AEW to 2 kinds of pathogenic fungi were over 75mm in diameter. Furthermore, treatment with AEW resulted in morphological changes such as bending and shrinking of the fungal hyphae surface. In addition, extracellular pH, conductivity, and absorbance at 260nm of the fungi hypha significantly increased post-treatment with AEW. Pathogenic morphology and IST sequencing analysis confirmed P. citrinum and A. sydowii as the primary pathogenic fungi, with their growth effectively inhibited by AEW.

Assessing the efficacy of electrolyzed water for sanitizing contaminated stainless-steel surfaces in the meat industry

Electrolyzed water (EW) presents promising potential as an alternative sanitation solution, offering cost savings and eliminating the need for harsh chemicals in food factories. This study investigates EW's efficacy in cleaning contaminated stainless-steel plates. Some plates were covered with meat residues, and the upper side of the plate's surfaces were inoculated with Escherichia coli ATCC 10536. Plates were then immersed in sterile distilled water (SDW) (pH: 7 ± 1), acidic electrolyzed water (AcEW) (free chlorine: 4.21 ± 0.05 mg/L, oxidation-reduction potential (ORP): 1168 ± 3.54 mV, pH: 2.74 ± 0.03), or alkaline electrolyzed water (AlEW) (ORP: 817 ± 8.49 mV, pH: 11.38 ± 0.01), at different temperatures (30 or 50 °C) for 30 s. The cleanliness of plates was confirmed microbiologically when no E. coli was detected, (below 1.0 log CFU/cm2). Treatment with SDW resulted in a modest reduction of the E. coli by 1.67 ± 0.84 log CFU/cm2 (±70% of the survived population). At 30 °C, E. coli was undetectable when AlEW was used without meat residue. At 50 °C, E. coli was undetectable when either AcEW or AlEW was used without meat residue. Visual and tactile inspections were conducted to validate cleanliness. The visual examination was performed after cleaning the plates with EW to ensure they appeared clean. However, tactile inspection indicated the presence of residues. Subsequent microbial analysis revealed 1.50 ± 0.87 log CFU/100 cm2 (±36% of the surviving population) of E. coli. This study demonstrated that meat residues on food-contact surfaces create a barrier to sanitation, necessitating mechanical action and heat for improved cleanliness.

Pretreatment and Non-thermal Processing Technologies for Quality Maintenance and Shelf-life Extension of Seafoods

The seafood industry faces significant challenges in preserving the quality and extending the shelf-life of its products to meet the demands of consumers for fresh, safe, and nutritious seafood. Apart from traditional pretreatments such as washing, sorting, and deheading, several emerging technologies like ozonized water (OW), acidic electrolyzed water (AEW), and plasma-activated water (PAW) have drawn attention for seafood industry. These innovative technologies not only improve quality of seafood but also effectively reduce contaminated microorganisms and enzymatic activity, thereby delaying spoilage. Furthermore, non-thermal processing technologies, including high pressure processing (HPP), cold plasma (CP) treatment, and modified atmosphere packaging (MAP), offer promising alternatives to conventional heat-based processes. These technologies are characterized by their ability to inactivate microorganisms and enzymes, while preserving the sensory attributes and nutritional value of seafood. HPP and MAP particularly have demonstrated their profound ability to extend the shelf-life of seafood products without compromising their quality or sensorial attributes. Furthermore, the synergistic effects of combining pretreatment and non-thermal processing techniques, have potential to prolong shelf-life and improve safety of seafood products. Thus, the integration of these pretreatments and technologies offers a promising avenue for enhancing the quality and safety of seafood products.

Health Benefits of High Voltage Electrostatic Field Processing of Fruits and Vegetables.

High voltage electrostatic field processing (HVEF) is a food preservation procedure frequently used to produce healthy minimally processed fruits and vegetables (F&V) as it reduces the growth of microorganisms and activates or inhibits various enzymes, thus retarding their natural ripening while preserving and even enhancing native nutritional quality and sensory characteristics. HVEF is one of the various nonthermal processing technology (NTPT) regarded as abiotic stress that can activate the antioxidant system of F&V and can also inhibith spoilage enzymes as, polyphenol oxidase (PPO), lipoxygenase (LOX), pectin methylesterase (PME), polygalacturonase (PG), cellulase (Cel), β-xylosidase, xyloglucan and endotransglycosylase/hydrolase, bringing positive effect on hardness, firmness, colour attributes, electric conductivity, antioxidant compounds, microstructure and decreasing electrolyte leakage (EL), malondialdehyde (MDA) contents and browning degree. This technique can also increase the contents of fructose, glucose, and sucrose and decrease the production of CO2 and H2O2. Additionally, it has been reported that HVEF could be used with other treatments, such as modified atmosphere packaging (MAP) and acidic electrolyzed water (AEW) treatment, to enhance its effects. Future works should deepen on elucidating the activation of the antioxidant systems by applying HVEF of critical enzymes related to the synthesis pathways of phenolic compounds (PC) and carotenoids (Car). Holistic approaches to the effects of HVEF on metabolism based on systems biology also need to be studied by considering the overall biochemical, physical, and process engineering related aspects of this technique.

Acidic Electrolyzed Water Maintains the Storage Quality of Postharvest Wampee Fruit by Activating the Disease Resistance.

Harvested wampee fruit is susceptible to disease, resulting in postharvest losses. Acidic electrolyzed water (AEW), a safe and innovative sterilization technology, plays a role in enhancing disease resistance in harvested produce. In this study, the efficacy of AEW in delaying wampee disease development was assessed, along with its association with disease resistance metabolism. Wampee fruit was treated with AEW (pH 2.5) at different available chlorine concentrations (ACCs) (20, 40, 60, and 80 mg/L) and subsequently stored at 25 °C for 8 days. Results revealed that 40 mg/L ACC in AEW (pH 2.5) was most effective in improving the postharvest quality of wampee fruit. Compared with control wampee fruit, those treated with 40 mg/L ACC in AEW exhibited lower incidence of fruit disease, higher pericarp lignin content, and higher activities of pericarp disease resistance enzymes (DREs), such as cinnamate-4-hydroxylase, phenylalanine ammonia-lyase, chitinase, β-1,3-glucanase, polyphenol oxidase, 4-coumarate CoA ligase, and cinnamyl alcohol dehydrogenase. These results suggested that AEW elevated DRE activities, promoted lignin accumulation, and ultimately enhanced disease resistance, suppressed disease development, and improved storage quality in harvested wampee fruit. Consequently, AEW emerged as a safe technology to mitigate the disease development and enhance the storage quality of harvested wampee fruit.

Efficient chlorine evolution of CuO modified RuO2 electrode and its application in preparation of electrochemical disinfectant

Electrochemical chlorine evolution reaction (CER) is one of the most important practical applications of electrochemical reaction, which can be used for electrochemical disinfection. The electrochemical disinfectant of acidic electrolyzed water (AEW) is obtained by electrolyzing extremely dilute chlorine-containing solution in ion-exchange membrane electrolyzer. In the anode area, HClO is produced by CER, which has a strong bactericidal effect. Due to the low concentration of chloride ion, it is necessary to improve the CER selectivity of the electrode in order to improve the efficiency of chlorine electrolysis. In this paper, CuO/RuO2 electrode was prepared by the two-step thermal decomposition method, and the surface morphology and electronic structure of RuO2 electrode were modified. Compared with the ordinary RuO2 electrode, the CER activity of CuO/RuO2 electrode is improved. For the oxygen evolution reaction (OER), the activity of CuO/RuO2 electrode is significantly lower than that of RuO2 electrode. The CER mechanism of CuO/RuO2 electrode is the second electron transfer, and the OER mechanism is the formation and transformation of OHads. The potential difference between CER and OER of CuO/RuO2-3 electrode is 105 mV, which is 52 mV higher than that of RuO2 electrode, so the selectivity of CER of CuO/RuO2 electrode is remarkably improved. During the preparation of AEW, the HClO of AEW2 (prepared by CuO/RuO2-3 electrode) is 0.72 mmol/L, which is 2.5 times that of AEW1 (prepared by RuO2 electrode). In the sterilization experiments on E. coli and B. subtilis, the germicidal efficacy of AEW2 (3.71 and 2.99 log10 CFU/mL) is obviously superior to that of AEW1 (0.76 and 0.61 log10 CFU/mL).

Enhancing biomass conversion: Efficient hemicellulose removal and cellulose saccharification in poplar with FeCl3 coupled with acidic electrolyzed water pretreatment

Due to the recalcitrant structure of woody biomass such as poplar, the efficient disassembly and separation of hemicellulose component from woody biomass is crucial for green biomass processing and full component utilization. This study presented an environmentally friendly approach to utilize acidic electrolyzed water (AEW) combined with metal salts and investigated its pretreatment effects on hemicellulose removal and cellulose and lignin retention under different conditions. Meanwhile, the structural properties and enzymatic hydrolysis performance of the pretreated residues were also characterized. As a result, under the optimized pretreatment conditions (0.03 mol/L FeCl3 with AEW at 180 °C for 10 min), hemicellulose removal from poplar wood reached 98.64 %, accompanied by xylose recovery rate of 98.46 %, cellulose retention rate of 93.43 % and lignin retention rate of 94.29 %. Enzymatic hydrolysis rate of the pretreated cellulose-enriched substrate reached 97.65 %. Furthermore, comprehensive structural characterizations revealed that FeCl3 coupled with AEW pretreatment resulted in surface damage to the poplar wood, effective removal of the amorphous hemicellulose component, and partial destruction of the cellulose crystallinity. In conclusion, FeCl3 coupled with AEW pretreatment effectively separates hemicellulose, leading to significant alterations in biomass composition and structure, ultimately resulting in improved enzymatic digestion. These results provide theoretical support for targeted dissociation of hemicellulose and full component utilization of woody biomass.

Acidic electrolyzed water treatment delays the senescence of ‘Lingwu long’ jujube fruit during cold storage by regulating energy and respiratory metabolism

Jujube fruit may rapidly undergo maturity and senescence during storage, seriously affecting its commercialization. The study aimed to evaluate the role of acidic electrolyzed water (AEW) on energy and respiratory metabolism, and senescence in jujube fruit during cold storage. The results indicated that AEW improved ATP content and energy charge via increasing succinate dehydrogenase, cytochrome C oxidase, H+-ATPase, and Ca2+-ATPase activities and delayed jujube fruit senescence. The treatment was found to improve the activities of nicotinamide adenine dinucleotide kinase, 6-phosphogluconate dehydrogenase and glucose-6-phosphate dehydrogenase, and the content of NADPH, and reduce oxidative stress. Transcriptome analysis suggested that AEW regulated the expression of the genes associated with glycolysis, citrate cycle, pentose phosphate pathway, oxidative phosphorylation, ROS metabolism, transcription factors, phenylpropane biosynthesis, cell wall metabolism, and plant hormone signal transduction. Therefore, we concluded that AEW may delay the senescence of postharvest jujube fruit by regulating expression of the relevant genes and metabolic pathways.

Biochemistry behind firmness retention of jujube fruit by combined treatment of acidic electrolyzed water and high-voltage electrostatic field.

Harvested jujube (Zizyphus jujuba Mill) is prone to softening due to active metabolism. This study investigated the effects of acidic electrolyzed water (AEW), high-voltage electrostatic field (HVEF) and their combination (AEW+HVEF) on softening and associated cell wall degrading enzymes (CWDEs), cell membrane integrity and antioxidant system of 'Huping' jujube during storage at 0±1°C. The results indicated that fruit subjected to AEW+HVEF, AEW or HVEF treatments maintained firmness 15.7%, 10.7%, and 5.3% higher than that of untreated control fruit at the end of 90days cool storage. Fruit treated with AEW+HVEF could better maintain cell membrane integrity and exhibit lower activities of CWDEs and higher antioxidant capacity than that treated with either AEW or HVEF. Correlation analysis suggested that inhibition of softening was associated with reduction of CWDEs activities, and maintenance of membrane integrity and antioxidant system.

Effect of different preservation treatments on the formation of semicarbazide in Litopenaeus vannamei and the potential molecular mechanisms

This research was conducted to explore the influence of different preservation treatments, namely sodium hypochlorite (NW), acidic electrolyzed water (AEW), acidic electrolyzed water ice (AEWI) and ozone water (OW) on the production of semicarbazide in Litopenaeus vannamei. Results showed that the level of semicarbazide increased along with the increase of sodium hypochlorite concentration and immersion time. For AEW group, with the increase of soaking time, the content of semicarbazide reached its maximum value after 24 h and then decreased. The semicarbazide content with the AEWI and OW treatments showed a downward trend with time. A strong negative correlation (r = –0.79) was observed between arginine content and semicarbazide in the NW group. For the former three treatment solutions, it was speculated that semicarbazide formation was related to amino acids decomposition with chlorine, while the semicarbazide produced during ozone treatment was presumed to originate from the biological metabolism of Litopenaeus vannamei.

Effects of electrolyzed water‐ultrasound treatment on pesticide removal in fresh‐cut potatoes with different cutting methods

AbstractElectrolyzed water (EW) and ultrasound (US) treatment are emerging effective means of reducing pesticides in fresh‐cut vegetables. However, their synergetic efficacy of degrading pesticides in fresh‐cut potatoes has not yet been revealed. Therefore, in this study, the effects of the combination of EW and US treatment on the removal of pesticides (chlorpyrifos, phorate, chlorothalonil, and procymidone) in fresh‐cut potato silks, strips, slices, and dices were investigated. Acidic electrolyzed water (AcEW) was selected as the optimum washing solution for pesticide removal on fresh‐cut potatoes. For the same type of fresh‐cut potato, the AcEW treatment with different sample‐to‐washing solution ratios showed no significant difference in the removal effect of different pesticides. The combined application of AcEW and US could efficiently reduce pesticides for different fresh‐cut potatoes. Furthermore, the optimal effects obtained varied greatly within the range of ultrasonic power 200–400 W and washing time 10–20 min. These results indicated that combining AcEW with US could serve as a promising method for pesticide reduction in fresh‐cut potatoes under respective appropriate process parameters.Practical ApplicationsPotato silks, strips, slices, and dices are the most common application form of fresh‐cut potatoes in Chinese dishes. Electrolyzed water (EW) and ultrasound (US) treatment have recently been used in reducing pesticides on fresh‐cut vegetables. However, their synergetic efficacy of degrading pesticides in fresh‐cut potatoes has not yet been revealed. This research provides a simple and novel method for pesticide removal on fresh‐cut potatoes. These steps combine Acidic electrolyzed water (AcEW) and US treatments to explore and improve the process parameters (sample‐to‐washing solution ratios, ultrasonic power, and washing time) of degrading pesticides for different fresh‐cut potatoes, including potato silks, strips, slices, and dices. Besides, the effect mechanism of different treatments on the degradation of pesticide residues was also discussed. The novel cleaning technology is expected to be popularized in vegetable processing plants.

Combined Treatment of Acidic Electrolyzed Water and High-Voltage Electrostatic Field Improves the Storage Quality of Huping Jujube (Ziziphus jujuba Mill. cv. Huping).

Fresh jujube is prone to rapid deterioration after harvest due to its active metabolism and rich nutrients. This study aimed to investigate the effects of acidic electrolyzed water (AEW), a high-voltage electrostatic field (HVEF) and a combination of AEW and HVEF (AEW + HVEF) treatments on the storage quality of Huping jujube (Ziziphus jujuba Mill. cv. Huping) stored at 0 ± 1 °C for 90 days. The results showed that the fruits treated with AEW + HVEF exhibited better storage quality than those treated with either AEW or HVEF alone. Specifically, the fruits treated with AEW + HVEF maintained higher levels of nutrients and taste compounds, including total soluble solid (TSS), total soluble sugar, reducing sugar and titratable acidity (TA), as well as lower respiration rate, weight loss, decay index and TSS/TA ratio. Additionally, the AEW + HVEF treatment could delay the increase in reddening index, a* and color change (ΔE) values, and the decrease in L* and b* values, by retarding the degradation of chlorophyll and accumulation of carotenoids and flavonoids, thereby preserving the more desirable appearance color. Furthermore, the combined treatment could enhance the glutathione reductase (GR) activity and 2,2'-azino-bis-(3-ethylbenzothizoline)-6-sulfonic acid (ABTS) +-scavenging ability. Thus, the AEW + HVEF treatment is a potential method for Huping jujube preservation.

Membrane phospholipids and nucleotide derivatives in “big six” Escherichia coli are targets of chlorine-based sanitisers during lettuce decontamination

Sodium chlorite (NaClO), the most commonly used sanitiser for fresh produce decontamination, is associated with the problems of pungency and corrosiveness. In search for a more environmentally- and user-friendly chlorine-based sanitiser, acidic electrolysed water (AEW), came into view in recent years. To determine whether AEW is an ideal alternative to NaClO, using ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS), this study thoroughly investigated the effectiveness of AEW and NaClO, both containing 4 mg/L of free available chlorine (FAC), in inhibiting the “big six” Escherichia coli pathogens (serotypes O26, O45, O103, O111, O121 and O145) on lettuce as well as the underlying antimicrobial mechanisms.The two sanitisers led to generally comparable E. coli cell reductions after a 10-min treatment, which indicated the decisive role of FAC in their antimicrobial effects. Among the strains, mortalities varied from approximately 0.68 log CFU/g in O111 under both treatments to 1.48 ± 0.04 log CFU/g in AEW-treated O26 and 1.23 ± 0.04 log CFU/g in NaClO-treated O45. O111's high resistance was confirmed by its almost undisturbed metabolome whereas the high lethality of O26 and O45 could be attributed to the loss of membrane phospholipids. Besides, retarded cell growth and energy deficiency as implied by a vast depletion of nucleotide derivatives further challenged O45's survival. Overall, the comparable sanitising efficacy and the similarity in antimicrobial mechanisms between the two sanitisers provided a scientific basis for replacing NaClO with the “greener” AEW for fresh produce sanitisation in the future.

Antimicrobial Effect of Slightly Acidic Electrolyzed (HOCl) Water on Botrytis cinerea of Cut Rose Flowers

Antimicrobial Effect of Slightly Acidic Electrolyzed (HOCl) Water on Botrytis cinerea of Cut Rose Flowers

Mechanism of acid and alkali electrolyzed water on the elimination of Listeria monocytogenes biofilm based on proteomic analysis

Acidic electrolyzed water is a relatively mature bactericide, which has a certain inhibitory effect on a variety of microorganisms, and is widely used in the field of food processing for cleaning, sterilization and disinfection. This study investigated the deactivation mechanisms of Listeria monocytogenes by Tandem Mass Tags quantitative proteomics analysis. Samples were treated through A1S4 (Alkaline electrolytic water treatment for 1 min and Acid electrolytic water treatment for 4 min), S3A1S1 (Acid electrolyzed water treatment 3 min, Alkaline electrolyzed water treatment 1 min and Acid electrolyzed water treatment 1 min), S5 (Acid electrolytic water treatment for 5 min). Proteomic analysis showed that the mechanism of acid alkaline electrolyzed water treatment to eliminate the inactivation of the biofilm of L. monocytogenes was related to protein transcription and extension, RNA processing and synthesis, gene regulation, sugar and amino acid transport and metabolism, signal transduction and ATP binding. The study on the influence mechanism and action mechanism of the combination of acidic and alkaline electrolyzed water to remove L. monocytogenes biofilm is helpful to understand the development of the process of removing biofilm by electrolyzed water, and provides theoretical support for the treatment of other microbial contamination problems in food processing by electrolyzed water.

Enhancement of safety and quality of ready-to-cook Asian green mussel using acidic electrolyzed water depuration in combination with sous vide cooking

Emerging technologies were combined to ensure the safety for consumers of Asian green mussel (AGM; Perna viridis). The combination of acidic electrolyzed water (AEW) depuration and sous vide cooking effectively reduced Vibrios while maintaining the quality of mussel. The use of AEW depuration combined with sous vide cooking at 100 °C for 1 min (D/SV-1) provided the yield of mussel meat of 27.22%, maintained the color, and texture properties. It could prevent the oxidation of polyunsaturated fatty acids and caused no changes in patterns of main proteins including paramyosin, actin and tropomyosin. Vibrio parahaemolyticus, V. vulnificus and Shewanella algae in AGM without treatment were 4.12, 3.00 and 3.30 log10 CFU/g, respectively. Those bacterial species were confirmed by MALDI Biotyper® technique. They were potentially inactivated by the selected process. In addition, the next generation sequencing (NGS) based on the 16S rRNA gene revealed a low percentage of V. vulnificus genome (2.72%) and the complete elimination of other naturally existing Vibrios. Overall, AEW depuration of raw mussels, followed by sous vide cooking could be a promising method for the production of safe ready-to-cook Asian green mussels for consumption. Industry relevanceCommon Asian green mussel (AGM; Perna viridis) may represent a risk for public health associated with pathogenic bacteria originating from the aquatic environment. It also deteriorates rapidly within 1–2 days because of its perishable nature, thus losing its market value. To tackle such problems, appropriate pretreatment using acidic electrolyzed water depuration, followed by sous vide cooking under proper conditions could be implemented for safety assurance of ready-to-cook AGM by eliminating both pathogenic and spoilage bacteria. Also, the eating quality could be maintained. As a consequence, the technology developed in the present study could offer an effective solution for ensuring customer safety without compromising eating quality. It could be commercially employed for seafood processing industry, especially for bivalve mollusks, e.g., mussels, scallops, and clams.

Bactericidal efficacy and mechanism of alkaline electrolyzed water co‐action with acidic electrolyzed water on Pseudomonas aeruginosa biofilm

AbstractHere, the bactericidal efficacy and mechanism of action of the combination of alkaline electrolyzed water (AlEW) and acidic electrolyzed water (AcEW) on Pseudomonas aeruginosa biofilm were investigated, in comparison with single AcEW or AlEW treatment. The mature P. aeruginosa biofilm was formed at 120 h of cultivation. The number of bacteria in the P. aeruginosa biofilm decreased by 7.87 and 2.51 Lg CFU/mL after single AcEW and single AlEW treatment for 8 min, while the sterilization rate reached 92.2% and 33.1%, respectively. The group of AcEW (7 min) co‐action with AlEW (1 min) had a P. aeruginosa sterilization rate of 85%. The AlEW (3 min) co‐action with AcEW (5 min) treatment showed the best bactericidal efficacy. With this treatment, the sterilization rate achieved 94.4%, and the extracellular protein, polysaccharide, and DNA were degraded with the ratios of 70.8%, 77.7%, and 70.5%, respectively. Thus, AlEW exhibited a major washing effect, which can destroy the biofilm structure of extracellular polymers to a certain extent, while AcEW displayed a significant bactericidal effect. These results suggest that the AlEW co‐action with AcEW treatment may be a promising candidate suitable for bacterial biofilm sterilization.

Mechanisms of acidic electrolyzed water killing bacteria

Given that acidic electrolyzed water (AEW), a newly invented and effective disinfectant, is widely used to kill bacteria in many fields, the sterilization mechanism of action is not clear yet. In this study, we demonstrated the molecular sterilization mechanism of AEW treatment on Gram-positive and Gram-negative bacteria (three prevalent food-borne pathogenic bacteria, i.e., Listeria monocytogenes, Salmonella typhimurium, and Vibrio parahemolyticus) using surface-enhanced Raman spectroscopy coupled with Fourier transform infrared spectroscopy, Scanning electron microscopy, atomic force microscope-Nanometer infrared imaging, antibiotic target test and qRT-PCR. AEW mainly induced oligopeptide destruction at the joints between alanine and N-acetylmuramic acid in bacterial cell wall, then forming holes in the cell wall, subsequently destroying disulfide bonds in cell membrane proteins, increasing the permeability of cell membrane, intracellular fluid dissipation and AEW invasion into the cell to demolish nucleic acids and other bioactive substances, finally leading to cell death. Moreover, the developed methodology could be a powerful tool for an extensive revelation of the response mechanisms of biological cells to environmental stimuli.

Effect of low temperature on the resistance of Listeria monocytogenes and Escherichia coli O157:H7 to acid electrolyzed water

Low temperature can affect the resistance of pathogenic bacteria to other external stress. The present study was envisaged to assess the tolerance of L. monocytogenes and E. coli O157:H7 to acidic electrolyzed water (AEW) under low temperature stress. AEW treatment caused a damage to cell membrane of the pathogenic bacteria, which led to protein leakage and DNA damage. Compared with the pathogenic bacteria cultured at 37 °C (pure culture), the L. monocytogenes and E. coli O157:H7 cells cultivated at low temperature presented a less damage and had a higher survival rate when exposed to AEW. Therefore, 4 °C or 10 °C grown bacteria were less susceptible to AEW than those cultured at 37 °C. And this phenomenon was verified when AEW was used to treat the pathogenic bacteria inoculated in salmon. In addition, transcriptomic sequencing technology (RNA-seq) was used to reveal the mechanism of AEW tolerance of L. monocytogenes under low temperature stress. Transcriptomic analysis showed the expression of the cold shock protein, regulation of DNA-templated transcription, ribosome pathway, phosphotransferase system (PTS), bacteria chemotaxis, SOS response and DNA repair were involved in the resistance of L. monocytogenes to AEW. We speculated that the direct modulation of the expression of cold shock protein CspD, the indirect effect on the expression of cspD by inhibiting the expression of Crp/Fnr family transcriptional regulator or enhancing the level of cAMP by regulating PTS could reduce the resistance of L. monocytogenes cultivated at 4 °C to AEW. Our study contributes to solving the problem of the reduced bacteriostatic effect in cold storage environment.