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In vitro inactivation of Escherichia coli, Staphylococcus aureus and Salmonella spp. using slightly acidic electrolyzed water
Abstract
In the current study, the effectiveness of slightly acidic electrolyzed water (SAEW) on an in vitro inactivation of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Salmonella spp. was evaluated and compared with other sanitizers. SAEW (pH 5.6, 23mg/l available chlorine concentration; ACC; and 940mV oxidation reduction potential; ORP) was generated by electrolysis of dilute solution of HCl (2%) in a chamber of a non-membrane electrolytic cell. One milliliter of bacteria suspension (ca. 10-11 log(10)CFU/ml) was mixed with 9ml of SAEW, strong acidic electrolyzed water (StAEW; ca. 50mg/l ACC), sodium hypochlorite solution (NaOCl; ca.120mg/l ACC) and distilled water (DW) as control and treated for 60s. SAEW effectively reduced the population of E. coli, S. aureus and Salmonella spp. by 5.1, 4.8, and 5.2 log(10)CFU/ml. Although, ACC of SAEW was more than 5 times lower than that of NaOCl solution, they showed no significant bactericidal difference (p>0.05). However, the bactericidal effect of StAEW was significantly higher (p<0.05) than SAEW and NaOCl solution in all cases. When tested with each individual test solution, E. coli, S. aureus and Salmonella spp. reductions were not significantly different (p>0.05). These findings indicate that SAEW with low available chlorine concentration can equally inactivate E. coli, S. aureus and Salmonella spp. as NaOCl solution and therefore SAEW shows a high potential of application in agriculture and food industry as an environmentally friendly disinfection agent.
... It was reported that SAEW may have equivalent or higher bactericidal activity than NaClO solution with lower available chlorine concentration (ACC) [6][7][8][9] . As an effective disinfectant, many studies have demonstrated the high bactericidal efficacy of SAEW against Escherichia coli, Staphylococcus aureus, Salmonella spp., Vibrio vulnificus and Vibrio parahaemolyticus [9][10][11] . SAEW contains a high concentration (approximately 95%) of hypochlorous acid [12,13] , which is more effective as a sanitizing agent than an equivalent concentration of the hypochlorite ion [14] . ...
... However, the inactivation effect of SAEW treatment increased with treating time and ACC level, which demonstrated that ACC is the main factor for the inactivation. It was consistent to other studies that the surviving population of microorganisms decreased with the increase of exposure time and ACC level [9][10][11] . For mixed-SAEW treated samples, the reduction of V. parahaemolyticus had no significant difference between 20 mg/mL ACC, 10 min and 15 mg/mL ACC, 10 min. ...
... The results in this paper were consistent with them. The inactivation effect increased with the increasing contacting time and the absence of organic matter, which is consisted with Issa-Zacharia et al. [10] As an effective, nontoxic and environmentally friendly disinfectant with high bactericidal effect, SAEW has large potential in practical use. ...
... Studies conducted previously compared the antibacterial effectiveness of SAEW at 20-30 mg/L available chlorine concentration with NaOCl at 100-150 mg/L available chlorine concentration. This is because NaOCl is commonly used as a sanitizer in food processing at 50-200 mg/L of available chlorine concentration (Hao et al., 2011;Issa-Zacharia et al., 2011, 2010a, 2010b. Also, there is little, if any, research on the effective dose of SAEW in terms of concentration and duration when sprayed into the air to reduce or eliminate airborne bacteria. ...
... Results of in vitro experiments showed that SAEW is effective at low dosage which makes it suitable to use not only at industrial levels or factories, but also at home and public places such as restaurants where hygiene must be assured. SAEW can also be considered as an alternative solution to conventional sanitizers such as NaOCl which is usually applied in higher dosage (Issa-Zacharia et al., 2010b;Koseki et al., 2004). The difference in bactericidal activity between SAEW and NaOCl lays on the presence of hypochlorous acid (HOCl), a very effective disinfectant, rather than the total available chlorine concentration. ...
Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slightly acidic electrolyzed water (SAEW) for reduction or removal of Escherichia coli , Pseudomonas aeruginosa and Staphylococcus epidermidis was evaluated. The bactericidal activity of SAEW and sodium hypochlorite (NaOCl) against E. coli and P. aeruginosa were compared through in vitro experiments. The effectiveness of SAEW spray was tested against S. epidermidis . Results showed that SAEW had a more powerful bactericidal activity than NaOCl at the same available chlorine concentrations. For E. coli , SAEW decreased the bacterial counts from 8.4 log 10 CFU/mL to less than 3.9 log 10 CFU/mL; NaOCl with the same available chlorine of 0.5 mg/L, caused a decrease from 8.4 log 10 CFU/mL to 7.1 log 10 CFU/mL. For P. aeruginosa , SAEW caused bacterial counts to decrease from 8.5 log 10 CFU/mL to less than 4.1 log 10 CFU/mL against 8.5 log 10 CFU/mL to 6.2 log 10 CFU/mL for NaOCl with the same available chlorine of 0.5 mg/L. Spray experiments showed that 10 mg/L of SAEW spray decreased the bacterial counts of S. epidermidis from 3.7 log 10 CFU/m ³ to 2.8 log 10 CFU/m ³ , with 20 mg/L causing a reduction from 3.8 log 10 CFU/m ³ to 0 CFU/m ³ . The overall findings of this study indicate that SAEW may be a promising disinfectant agent either as a solution or spray.
... Chlorine in the form of HOCl possesses the highest sanitization power within the pH value of 5.0 to 6.5 [14]. To date, most studies have investigated the sanitization potency of SAEW to the extent of 30 ppm of available chlorine concentration [6,11,15,16]. However in 2013, MFDS in Korea revised the SAEW standard concentration of available chlorine from 10-30 ppm to 10-80 ppm for sterilization purpose of fresh produce [17]. Thus, more research is required on the generation and utilization of high concentrated SAEW and the demand of new apparatus for continuous production has increased. ...
... In this study, we have focused on producing SAEW containing 40 ppm of available chlorine at a production flow rate of 5 L/min. In order to produce a highly concentrated SAEW with a large flow rate, the inlet flow of HCl should also be increased [23] along with the current range [24] as compared to previous studies [13,16]. Hence, the electrolyte flow rate was varied between 2-4 mL/min. ...
Having a mild acidic pH of 5-6.5, Hypochlorous acid (HOCl) is a harmless disinfectant having excellent sterilizing capability for use in agriculture, medicine and food industry. Recently, the use of non-diaphragm electrolytic cell has shown great potential in producing Slightly acidic electrolyzed water (SAEW). However, the effect of various physical properties such as electrode gap, flow rate, current, bubble formation and temperature conditions are still under investigation. In this study, we produced 40 ppm SAEW by using a self-developed non-diaphragm electrolytic cell that electrolyzed 6 % Hydrochloric acid (HCl) with H2 and Cl2 gas as by products. The tested range of electrolyte flow rate was 2-4 mL/min. The effect of current was studied in the range of 10-15 A. The results indicate that bubble generation by increased current decreased the average convection heat transfer coefficient between the electrode and electrolyte resulting in increased temperature. Moreover, the bubbles reduced the surface area for an efficient electrolytic reaction resulting in a decrease in available chlorine concentration. Hence, an optimized flow rate of 3 mL/min at 13 A current were found to be best process conditions for SAEW generation when the electrode size is 4 cm by 14 cm. Furthermore, the produced high concentrated HOCl showed excellent sanitization efficacy against various Escherichia coli concentrations (10⁵-10⁸ cfu/mL).
... jejuni), Salmonella spp., and Listeria monocytogenes (L. monocytogenes) are considered some of the most important pathogens that can cause illness and death[3]. Moreover, Yersiniosis, an infection caused by Yersinia enterocolitica (Y. ...
... Chemical solutions such as sodium hypochlorite, chlorine dioxide, hydrogen peroxide, organic acids, and ozone have been used as sanitizers in the food industry. The most commonly and widely used sanitizer is chlorinated water of 50–200 ppm[3]. Strong acid electrolyzed water (pH 2.5 ± 0.2; 20–60 mg/L available chlorine concentration (ACC)) and slightly acidic electrolyzed water (SAEW) (pH 5.0–6.5; ...
The aim of the study was to investigate the effect of using direct electric current (DC) of 0, 200, and 400 mA for five minutes on the physiochemical properties, cytotoxicity, antibacterial, and antioxidant activity of sodium alginate hydrosols with different sodium chloride concentrations. The pH, oxidation-reduction potential (ORP), electrical conductivity (EC), and available chlorine concentration (ACC) were measured. The effect of sodium alginate hydrosols treated with DC on Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Micrococcus luteus, Escherichia coli, Salmonella enteritidis, Yersinia enterocolitica, Pseudomonas fluorescence, and RAW 264.7 and L929 cells was investigated. Subsequently, the antioxidant properties of hydrosols were evaluated by determining the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and ferric reducing antioxidant power (FRAP). The results have shown that after applying 400 mA in hydrosol samples with 0.1% and 0.2% NaCl all tested bacteria were inactivated. The ACC concentration of C400 samples with NaCl was equal to 13.95 and 19.71 mg/L, respectively. The cytotoxicity analysis revealed that optimized electric field conditions and the addition of sodium chloride allow for the avoidance of toxicity effects on normal cells without disturbing the antibacterial effects. Due to the presence of oxidizing substances, the DPPH of variants treated with DC was lower than the DPPH of control samples.
... FAC is widely believed to achieve disinfection via disrupting the osmotic homeostasis within the bacterial cells whereas other findings indicate that disruption of membrane structure is also responsible for its wide-spectrum antimicrobial effects (Deza et al., 2003;Issa-Zacharia et al., 2010;Kiura et al., 2002;Wu et al., 2021). To explore the antimicrobial mechanisms of the chlorine-based sanitisers on the "big six" E. coli strains, metabolic alterations within the E. coli cells induced by the treatments must be investigated. ...
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.
... It is produced by adding low concentrations of hydrochloric acid and or sodium chloride to soften water and electrolyzing it in a diaphragm electrolytic cell. The pH of SAEW ranged from 5.0-6.5, and the ORP of REDOX potential was more significant than 800-900 mV [96][97][98][99]. Figure 4 shows a schematic diagram of systems producing AEW, BEW, and SAEW. Electrolytic water reacts with organic matter to generate ordinary water, effectively reducing environmental pollution. ...
In an era of rapid technological development, ultrasound technology is being used in a wide range of industries. The use of ultrasound technology in fruit and vegetable processing to improve production efficiency and product quality has been an important research topic. The cleaning of whole fresh fruits and vegetables is an important part of fruit and vegetable processing. This paper discusses the development process of components of the ultrasonic equipment, the application of ultrasonic technology in fruit and vegetable cleaning, and the research advances in ultrasonic cleaning technology. Moreover, the feasibility of ultrasonication of fruits and vegetables for cleaning from the perspectives of microbial inactivation, commodity storage, and sensory analysis were discussed. Finally, the paper identified the inevitable disadvantages of cavitation noise, erosion, and tissue damage in fruit and vegetable processing and points out the future directions of ultrasonic fruit and vegetable cleaning technology.
... Involvement of Free Radical Studies have demonstrated that electrolysis of water produce ROS, which was reported being a disinfectant mechanism of EW to pathogen. [57], [66]- [68] Yang and others reported that the application of EW on Listeria innocula resulted in increased generation of ROS, which serves as a disinfectant mechanism. [63] In addition, Jeong in 2006 demonstrated that ROS serve as an additional disinfectants contributed to anti-microorganism, similar to chlorine compounds. ...
... Since the colonization of these organisms, particularly Staphylococcus spp., could lead to chronic wound infection, the antibacterial effect of ionized water at different pH was tested on some selected species as well as Gram-negative bacterial species. Although, studies have shown that electrolyzed water possesses an effective antibacterial activity against common surface bacterial isolate like S. aureus [11,12], this is the first report on the effects of ionized water on bacterial isolates of equine wounds. ...
Background and Aim: Horse wounds can be easily infected with bacteria depending on the nature of its cause such as laceration, abrasion, or puncture as well as the nature of its environment. Various treatments are available in managing open wounds, including the usage of topical antibiotics and antiseptics. However, antibiotic resistance has been a major concern attributed with chronic wound infection. The aim of this study was to test the efficacy of ionized water at different pH against the growth of common bacteria from horse wounds.
Materials and Methods: Ten swab samples from equine infected wounds were collected and bacteria isolation and identification were performed. The antibacterial effect of the ionized water of pH 2.5, 4.5, 7.0, and 11.5 was tested on Staphylococcus aureus, Staphylococcus pseudintermedius, Staphylococcus intermedius, Escherichia coli, Pantoea agglomerans, and Klebsiella pneumoniae. The time-kill profiles of the ionized waters were determined at time 0, 2, 4, 6, and 8 h.
Results: Ionized water of pH 2.5 and 4.5 showed antibacterial activity against S. aureus, S. pseudintermedius, and S. intermedius with significant (p>0.05) reduction in colony-forming unit/mL within 2-8 h. The degree of bactericidal effect of the acidic ionized water differs between the species with S. intermedius more susceptible. However, there was no antibacterial effect at pH 2.5, 4.5, 7.0, and 11.5 on the Gram-negative bacteria tested.
Conclusion: Ionized water of pH 2.5 and 4.5 is effective in minimizing the growth of Gram-positive bacteria; thus it could be of clinical importance as an antiseptic for surface wound lavage in horses.
... Slightly acidic electrolyzed water (SAEW), usually with a pH value of 5.0-6.5, is considered to be an effective antimicrobial agent in recent years [18]. SAEW exhibits strong antimicrobial activity against many different kinds of microorganisms such as Escherichia coli [19], Staphylococcus aureus [19,20], Salmonella spp [21], Vibrio parahaemolyticus [22], and Bacillus cereus spores, etc. [23,24]. SAEW has been used to disinfect fresh fruits [25], vegetables [26,27], fish products [28,29], and meat products [30]. ...
Effects of ultrasound (US, 300, 400, and 500 W) and slightly acidic electrolyzed water (SAEW, 10, 30, and 50 mg/L) combination on inactivating Rhizopus stolonifer in sweet potato tuberous roots (TRs) were investigated. US at 300, 400, and 500 W simultaneous SAEW with available chlorine concentration of 50 mg/L at 40 and 55 °C for 10 min significantly inhibited colony diameters (from 90.00 to 6.00-71.62 mm) and spores germination (p < 0.05). US+SAEW treatment could destroy cell membrane integrity and lead to the leakage of nucleic acids and proteins (p < 0.05). Scanning and transmission electron microscopy results showed that US+SAEW treatment could damage ultrastructure of R. stolonifer, resulted in severe cell-wall pitting, completely disrupted into debris, apparent separation of plasma wall, massive vacuoles space, and indistinct intracellular organelles. US500+SAEW50 treatment at 40 and 55 °C increased cell membrane permeability, and decreased mitochondrial membrane potential of R. stolonifer. In addition, US500+SAEW50 at 40 °C and US300+SAEW50 at 55 °C controlled R. stolonifer growth in sweet potato TRs during 20 days of storage, suggesting effective inhibition on the infection of R. stolonifer. Therefore, US+SAEW treatment could be a new efficient alternative method for storing and preserving sweet potato TRs.
... The flask was then shaken continuously for 5 min at room temperature (~30 o C). After that, the concentration of survived bacteria was determined as in the method above 11,12 . The negative control experiment was conducted in the same procedure with a phosphate buffer saline solution (0.9 mL, pH 9.0) replacing the neutral electrolysed water. ...
This study evaluated physicochemical and antibacterial properties of neutral electrolyzed water (NEW) produced by electrolyzing NaCl solutions. pH, total chlorine content (TC) and oxidation reduction potential (ORP) of NEW increased to equilibrium values when increasing NaCl concentration (0.20% - 1.5%) and electrolysis time (0 – 240 minute). The pH and ORP values increased sharply in the first 15-min of the electrolysis and then was stabilized in the ranges of 8.5-9.5 and 400-500 mV, respectively. Increasing NaCl concentration did not change the stabilized values of pH and ORP, but significantly increased (p<0.05) TC. Furthermore, we studied antibacterial activity of NEW against Escherichia coli and Salmonella enterica in suspension and in ground pork. Interestingly, 085% NaCl NEW after 10-min electrolysis reduced 7 log CFU/mL of E. coli and 2 log CFU/mL of S. enterica. This resistance of S. enterica toward NEW was possibly due to its biofilm-forming ability.
Pdf available at: http://www.orientjchem.org/vol36no3/physicochemical-properties-and-bactericidal-effects-of-neutral-electrolyzed-water-against-escherichia-coli-and-salmonella-enterica-on-ground-pork/
... It is suggested by another study that increasing exposure time for EW treatment can increase antimicrobial efficacy on L. monocytogenescontaminated cold-smoked salmon [31]. Large body of studies have showed that increased exposure time of EW to foodborne pathogen can enhance log reduction, which indicates the antimicrobial efficacy of EW [38] , [39] , [41] [72] , [88] , [91]- [93] D. Water hardness Water hardness was investigated as a factor affect not only the properties of EW but also the antimicrobial efficacy. Increased water hardness from 0 to 50 mg/L resulted in increased log reduction of E. coli O157: H7 from 5.8 to 6.4 log CFU/mL due to 40% increased free chlorine level as water hardness increases. ...
Uncontrolled growth of microorganism in foodstuff pose a severe challenge to the food industry, as it could leads to food spoilage, or even foodborne disease if the microorganism is pathogenic. To deal with these threats, sanitizers has been widely applied widely by food industry. In the last two decades, electrolyzed water (EW) has been food to be a promising new sanitizer for food industry, as it is more environmentally friendly compared to conventional chlorine-based disinfectants. This paper reviews the recent progress on the application of EW as a food sanitizer. EW was produced by the electrolysis of diluted NaCl (or HCl) solution and could be classified into several subgroups (acid EW, slightly EW, neutral EW, alkaline EW, low concentration) based on their pH and available chlorine concentration. The efficacy of using EW to inhibit the growth of several most important microorganism of food safety concern were proven by numerous studies. Besides, the application of EW has been seldomly associated with detrimental effects on the nutritional and sensory proprieties of food. However, its antimicrobial potency was affected by factors such as pH, temperature, storage time, and organic matter.
... The use of US and SAEW has been reported as alternative technologies in the meat industry (Flores et al., 2017) TA B L E 2 Total phenolic compounds mg GAE.100/g flour of Citrus reticulata extracted with functional electrolysed water using ultrasound (real and coded variables (in parentheses)) minimum corrosive potential, the fact that they are less harmful to the environment, and the fact that they require hardly any safety precautions (Zacharia, Kamitani, Tiisekwa, Morita, & Iwasaki, 2010). ...
The aim of this study was to evaluate the use of acid electrolyzed water, basic electrolyzed water, and slightly acidic electrolyzed water (AEW, BEW, and SAEW, respectively) as solvents in ultrasound (US) to extract bioactive compounds from Citrus reticulata. The influence of the intensity (17–85 W/cm2) and pulse cycles (0.5–1.0 dimensionless) was investigated in relation to the extraction of total phenolics (TP), total flavonoids (TF), and antioxidant activity (FRAP). The extract obtained with US + SAEW presented the highest values for TP (4,324.32 mg GAE.100/g of tangerine peel) and FRAP (663.69 µmol TEAC.100/g of tangerine peel). The highest TF content was found for US + AEW (691.76 mg EQ.100/g of tangerine peel). Response surface methodology showed that higher US intensities improved the extraction of phenolic compounds. Regarding the flavonoid compounds, the highest extractions were obtained at the central points (intensity (51 W/cm2) and cycle (0.75). The results showed that US and electrolyzed water successfully extracted bioactive compounds from tangerine peel; the processing time was also reduced by around 87.5%. These results were higher than those in the literature regarding conventional extraction techniques. The combination of unconventional techniques (ultrasound and electrolyzed water as solvent) is characterized as a new methodology for the extraction of bioactive compounds from tangerine peel. This technique is environmental friendly due to the use of fruit residues, as well as the absence of organic solvents, and lower levels of energy use. The extract provided a higher content of total phenolics and total flavonoids than conventional methods. The extract can be incorporated into foods to provide nutritional quality and antioxidant properties. This technique is easily incorporated at the industrial level and is low cost after the purchase of the relevant equipment.
... This event may have facilitated the SAEW entry into the bacterial cell. Similar behavior was not observed at 130 kHz, once the smaller bubbles were formed, with a high penetration power in the bacterial cells, thus generating a small amount of energy, which promotes the formation of small temporary channels in the cytoplasmic membrane(Chemat et al., 2011).The action of the US on the different types of bacteria can vary according to the shape (cocci or bacilli), cell wall composition, ideal growth temperature, and pH(Pagan, Mañas, Raso, & Condon, 1999).Yokoyama et al. (2007) andZacharia, Kamitani, Tisekwa, Morita, and Iwasaki (2010) reported that the differences in cell structure between gram-positive and negative bacteria may prevent HOCl from penetrating the microbial cell. The thick peptidoglycan layer of gram-positive bacteria would provide a greater resistance to the mechanical stress produced by the cavitation in US(Joyce, Al-Hashimi, & Mason, 2011). ...
Pre-chilling leads to a temperature decline of the pre-rigor muscle of poultry carcasses, and a reduction of the initial bacterial load may occur. Both ultrasound (US) and slightly acidic electrolyzed water (SAEW) have been used alone in the meat industry for the manufacture of emulsions, pasteurization, and prevention of bacteria growth. However, the impact of the combination of these technologies during the pre-chilling of chicken carcasses has not been evaluated. In this study, breast chicken cylinders (CBCs) were pre-chilled for 10 min at 10 °C using SAEW and different US frequencies (25 and 130 kHz). The microbiological characteristics, lipid and protein oxidation, shear force, and anaerobic glycolysis were evaluated. The US + SAEW combination led to an effective reduction (P < 0.05) of enterobacteria, mesophilic bacteria, lactic acid bacteria, and psychrotrophic bacteria, while the lipid and protein oxidation, shear force, anaerobic glycolysis, and muscle structure were not affected (P > 0.05). Therefore, the combination of these technologies may be promising in the pre-chilling stage of chicken carcasses.
... In other studies, EGHA was used successfully as decontamination strategy to control foodborne pathogens and spoilage organisms on different fresh foodstuffs (Cao et al., 2009;Ding et al., 2011;Grac¸a et al., 2011;Issa-Zacharia et al., 2010;Keskinen et al., 2009;Park et al., 2008;Thorn et al., 2017). According to Kalchayanand et al. (2008), EGHA had intermediate effects on cheek meat experimentally contaminated with E. coli O157:H7, as compared with hot water and lactic acid. ...
Antimicrobial treatments could help to decrease the transmission of microorganisms to beef carcasses and abattoir environments. The aim of this study was to evaluate the effectiveness of interventions in reducing Shiga toxin genes ( stx1 and stx2) presence in a commercial abattoir. Intervention measures included the application of electrolytically generated hypochlorous acid to steer pens (experiment 1), chlorinated water, electrolytically generated hypochlorous acid, and isoclor to steer pens (experiment 2), electrolytically generated hypochlorous acid to knocking pens (experiment 3), and aqueous ozone and electrolytically generated hypochlorous acid onto beef carcasses (experiment 4). Detection of stx in samples was performed with BAX® System Real-Time PCR Assay. Our results showed that treatment with pressurized electrolytically generated hypochlorous acid and isoclor were effective to reduce stx presence from hides on steer pens. Although there is no single strategy to ensure the reduction of stx presence in a commercial abattoir, the combined application of several antimicrobial interventions would be ideal.
... Moreover, many killing microorganisms' procedures have been suggested to interpret the poisonous bacteria removal upon techniques based on EF application, which may be listed as [3, 37- . Following the electrochemical design, a range of produced oxidants has been observed throughout the period of the process [3,41]. As a rule, chloride-containing electrolytes generate active chlorine species (like Cl 2 , HOCl, and OCl -) which are fundamental oxidants responsible for demobilizing pathogenic cell wall structures [42,43]. ...
Electrocoagulation (EC) process has been largely found efficient in terms of pathogens removal. This literature review focuses on describing the key killing microorganisms' pathway followed throughout the EC technique. The pathogens removal route using EC is deeply assessed following the practical experimentation realized during these last years. Physical elimination and chemical deactivation pathways are suggested for bacteria reduction procedure throughout the EC method employing Fe/Al anodes: (1) entrapping pathogens in flocs, (2) destabilizing negatively charged microbes through sweep flocculation, and (3) demobilizing bacteria cell envelopes upon electrochemically formed reactive oxygen species or direct impact of the electric field. Finally, deepest investigation works on microbes' removal through EC are more called to promote the industrial applications of this performant technology.
... High-purity limonene, a major component of lemon essential oil found in the peels, can be used as fragrance, flavour, insecticide, or renewable solvent for coating or replacing aromatic and mineral oils [3]. Researchers worldwide are investigating this substance as a method to protect food from bacterial growth without the need for harmful chemicals [4]. ...
... We evaluated the physicochemical properties of PAW generated using the discharge times of 30, 60, and 120 min; oxidation/reduction potential (ORP), EC, levels of hydrogen peroxide, major excited active species (nitrite and nitrate anion), and pH levels were tested (Table 1). ORP is used to assess the oxidising ability of PAW, and activity is related to the concentration or strength of an oxidiser (Issa-Zacharia, Kamitani, Tiisekwa, Morita, & Iwasaki, 2010;McFerson, 1993). The ORP value indirectly indicates the levels of global ROS in PAW (Shen et al., 2016). ...
Improving the microbiological quality of salted Chinese cabbage, used in kimchi, an important part of the Asian culinary scene, is critical for minimising exposure to foodborne pathogens. This study evaluated the effects of a sequential combination of washing treatments using plasma-activated water (PAW), tap water, and sodium hypochlorite (NaOCl) and mild heating (MH) at 60 °C on the inactivation of background microbiota and inoculated foodborne pathogens and the quality of shredded salted Chinese cabbages. Treatment with 120-PAW alone resulted in 2.0, 2.2, 1.8, and 0.9 log CFU/g reduction in mesophilic aerobic bacteria, lactic acid bacteria, yeast and moulds, and coliforms, respectively, while subsequent MH treatment reduced the counts of lactic acid bacteria, yeast and moulds, and coliforms to below detection limits. Sequential combination of washing with 120-PAW followed by MH caused 3.4 and 3.7 log CFU/g reductions in Listeria monocytogenes and Staphylococcus aureus inoculated into salted Chinese cabbages. The combined treatment caused negligible changes in moisture content, reducing sugar content, instrumental hardness, and CIE colour values. The salinity and peroxidase activity were significantly (P < 0.05) reduced compared to that of the untreated cabbage. Thus, sequential treatment of washing with PAW and MH at 60 °C can improve the microbiological quality of salted Chinese cabbage.
... High-purity limonene, a major component of lemon essential oil found in the peels, can be used as fragrance, flavour, insecticide, or renewable solvent for coating or replacing aromatic and mineral oils [3]. Researchers worldwide are investigating this substance as a method to protect food from bacterial growth without the need for harmful chemicals [4]. ...
Traditional edible barbecue products use with lemon juice not only make the barbecue more delicious but also reduce the risk of PAHs in the barbecue products. One of the major economics crops in Taiwan, the waste from citrus fruits was very tremendous mass. However, the peelings of citrus fruits are rich in essential oil, especially, the limonene is the major. Whether the anti-carcinogenesis activities of terpene, such as limonene, in citrus fruits essential oil extraction. This study to demonstrate the PAHs content in fish skin increased markedly after being roasted at 210℃ for 20 minutes and greater mutagenicity risk of roasted fish skin was observed by Ame's test. The reduction of mutagenicity risk of roasted fish skin, which the antimutagenic abilities of substances in descending order were limonene > cold pressure oil > lemon >grapefruit. The antimutagenicity rate and ability of the three extracts were limonene: 18–23%; cold-pressed lemon oil: 18–22%; and steam distilled lemon essential oil: 8–16%. The obvious anti- mutagenicity effects against the PAHs mutagenicity of roasted fish skins can be found in citrus fruits essential oil extraction.
... Trong các nghiên cứu gần đây, A. Issa-Zacharia và các công sự [7,8] đã so sánh hiệu quả diệt khuẩn của dung dịch AEW với dung dịch NaOCl đối với các vi khuẩn cần kiểm soát trong quá trình chế biến thủy sản là E. coli, S. aureus và Salmonella spp ở dạng dịch lỏng tinh khiết. Các kết quả cho thấy, hiệu quả diệt khuẩn của AEW cao hơn rõ rệt (p < 0,05) so với NaOCl trong mọi trường hợp. ...
Hiệu quả khử khuẩn của dung dịch hoạt hóa điện hóa Supowa đã được xác định đối với các vi khuẩn chủng quốc tế E.Coli (ATCC®14169™ ), S. aureus (ATCC®25923™), Salmonella (ATCC®25241™) và L.monocytogenes (ATCC®7644™). Khi có mặt peptone 0,1 %, các vi khuẩn trên ở mật độ 108 CFU/ml bị tiêu diệt hoàn toàn sau 2 phút tiếp xúc với dung dịch Supowa có nồng độ chất ôxy hóa 50 mg/l (tính tương đương với clo hoạt tính). Khi khử trùng bề mặt bàn inox và rổ nhựa, hiệu quả khử khuẩn của phương pháp sử dụng Supowa tốt hơn nhiều so với phương pháp thường qui (p < 0,05). Trong trường hợp khử trùng bạch tuộc nguyên liệu, Supowa thể hiện hiệu quả khử trùng tốt hơn phương pháp thường qui nhưng chưa rõ rệt (p > 0,05). Dung dịch Supowa được đề xuất sử dụng làm tác nhân khử trùng thay thế Ca(OCl)2 trong chế biến thủy sản.
... However, the use of new technologies for the generation of chlorinated water, such as electrolysis, can make this process more practical, simple and environmentally appropriate (Rahman et al., 2016). Due to its minimal corrosive potential, SAEW may be less aggressive to human health and the environment, requiring minimum safety processes to manipulate it (Zacharia et al., 2010). The operational costs associated with the application of SAEW can also be lesser because of the possibility of local production (Al-Haq et al., 2005). ...
The quality of meat from different animal species is defined by chemical, physical sensory and microbiological characteristics, which can be influenced by procedures during the slaughter of animals. Technologies such as ultrasound (US) and slightly acidic electrolyzed water (SAEW) are being studied in order to assist in food processing and in developing methods that are economically viable and environmentally sustainable. The aim of this paper is to discuss the relationship between US and SAEW in relation to tenderness, microbiology, and oxidation of meat. The meat industry was a pioneer in the use of the ultrasound, which initially aimed to determine the layer of fat on carcasses and subsequently improve the tenderness of the meat. Recently studies mention that the ultrasound and SAEW can influence the microbiological parameters. The combination of both technologies should also be considered, with the possibility of enhancing the antimicrobial effects. However, there is little information regarding oxidative parameters promoted in meat for these two alternative technologies, where the individual or when interspersed use. Knowing the actions and consequences of ultrasound and SAEW in meat will enable the opening of new perspectives about the application of these technologies in the meat industry.
... SAEW can decrease the environmental damage and corrosive impact of the food industry. Its antimicrobial activity is predominately caused by potential oxidative damage of biomolecules by HOCl which has been studied and confirmed (Issa-Zacharia et al., 2010;Mansur et al., 2015;Tango et al., 2015). The employment of a mechanical force with SAEW or in combination with other sanitizers during the washing process leads to significant microbial reduction on food products (Afari et al., 2016;Mansur et al., 2015;Tango et al., 2014a,b). ...
Effect of sequential combination of slightly acidic electrolyzed water (SAEW) with chemical and physical treatments on bacterial decontamination on fruits was investigated determined in this study. Effect of treatments on microbial and sensory quality was also analyzed after subsequent storage at 4 °C and room temperature (RT, 23 ± 0.15 °C). Whole apple and tomato fruits were inoculated with cocktail strains of Escherichia coli O157:H7 and Listeria monocytogenes. Uninoculated and inoculated fruits were washed first with distilled water (DW), calcium oxide (CaO), fumaric acid (FA), and SAEW at RT for 3 min. Combinations were performed by adding treatment one at a time to SAEW as following FA + SAEW, CaO + FA + SAEW, and CaO + FA + SAEW + ultrasonication (US) or microbubbles (MB). All the sanitizer treatments resulted in significant (p < 0.05) bacterial reduction compared to DW used as control. Increasing the treatments in combination from FA + SAEW to CaO + FA + SAEW + US resulted in an increased bacterial decontamination. The cavitation induced by ultrasonication in FA + SAEW solution resulted in a higher additive effect in decontamination of Escherichia coli O157:H7 and Listeria monocytogenes compare to the agitation generated by microbubble generator in FA + SAEW solution. CaO + FA + SAEW and CaO + FA + SAEW + US were effective in improving the microbial safety and quality of apple fruits. However, additional treatment of US impacted on the quality of tomato fruits during storage at RT. Therefore, a combination of SAEW with sanitizers (CaO and FA) and mechanical force (Ultrasonication) has the potential to be used in postharvest sanitation processing in the fresh fruit industry.
... Mild process can preserve freshness and the characteristic flavor of food products. However, fruits and vegetables that have been mildly processed (washing, cutting, cooking, mixing, canning, packing etc.) can harbor foodborne pathogens such as Staphylococcus aureus, enterohemorrhagic Escherichia coli, Campylobacter jenuni, Salmonella spp., and Listeria monocytogenes (Issa-Zacharia, Kamitani, Miwa, Muhimbula, & Iwasaki, 2011;Issa-Zacharia, Kamitani, Tiisekwa, Morita, & Iwasaki, 2010), which cause serious health problems. These bacteria can multiply during process, transportation, distribution, storage, and handling. ...
Time to detection experiments (TTD) based on turbidometry using an automatic Bioscreen C is a useful and straightforward method for estimating microbial growth parameters (lag time (λ), growth rate (_μ_) and “work to be done” (h0)) at constant temperature. This study investigated the effects of slightly acidic electrolyzed water (SAEW) and heat treatment on _Listeria monocytogenes_ growth at different recovery temperatures (10 °C, 15 °C, 25 °C, and 30 °C). Similar surviving and sublethally injured _L_. _monocytogenes_ populations were obtained by heat treatment (55 °C for 10 min) and SAEW treatment (available chlorine concentration of 30 mg/l and ratio of bacteria against SAEW of 8:2 for 30 s). In these experimental conditions, stresses had greater impact on the λ and h0 parameter in comparison with recovery temperature while there was no great change in growth rate under isothermal conditions. Larger λ values and h0 parameters were observed in sublethal-heat injured _L_. _monocytogenes_ (the maximum λ and h0 parameters are 30.199 h and 1.6492) as compared to SAEW groups (the maximum λ and h0 parameters are 22.634 h and 1.4396). The sensitivity analysis of SAEW and heat treatments on h0 parameter indicated that SAEW treatment showed a higher influence. The collinearity diagnostics of independent variables [recovery temperature (T), _μ_, _λ_] for dependent variable (h0 parameter) demonstrated that T, μ and λ had strong collinearity. In addition, the established secondary models in this study have good performances on predicting the effect of recovery temperature on bacterial growth parameters.
... Acidic electrolyzed water helps control foliar diseases of many plants (Fujiwara et al. 2000;Guentzel et al. 2011;Hou et al. 2012;Jia et al. 2015;Kusakari et al. 2013;Mueller et al. 2003), but it occasionally leads to foliage phytotoxicity on some crops (Fujiwara et al. 2000;Mueller et al. 2003). It is also hazardous to humans and the environment and corrodes farm equipment (Issa-Zacharia et al. 2010). Recently, a neutral electrolyzed water (NEW) treatment has been tested for sanitizing foods and is now recognized as a disinfectant of microorganisms on food (Guentzel et al. 2008;Huang et al. 2008;Monnin et al. 2012;Torlak 2014). ...
Neutral electrolyzed water (NEW: pH 6.5–7.5) applied through an overhead irrigation system was evaluated for control of strawberry anthracnose caused by Colletotrichum fructicola. Conidia of the pathogen were completely killed by a 10-s exposure to 10.0 mg/L of available chlorine in the NEW. Disease suppression was significantly higher using the NEW treatment through overhead irrigation, either alone or combined with fungicides, than using conventional fungicides. Plants had no visible phytotoxicity after the NEW treatment, even when combined with fungicides. Thus, the NEW treatment was effective at controlling anthracnose caused by C. fructicola.
... As expected, TVC values of the untreated samples increased at a faster rate than those of all treated ones, indicating antimicrobial effect of SAEW and EBLCE, which confirms in previous studies (Chen et al. 2013;Forgháni and Oh 2013;Hao et al. 2013 Complete inactivation or elimination of microorganisms is still a challenge to the fishery industry, so developing new approaches as well as improving present techniques is necessary. SAEW was reported to inhibit the growth of some bacteria including Escherichia coli, Listeria monocytogenes, Salmonella spp., Bacillus cereus and Staphylococcus aureus (Issa-Zacharia et al. 2010;Nan et al. 2010;Koide et al. 2011), which are considered as common foodborne pathogens of major public health concern. Although SAEW is well known as an efficient antimicrobial agent, microbial reductions from SAEW pretreatment alone are not enough to ensure food safety. ...
Slightly acidic electrolyzed water (SAEW) and ebony-bamboo leaves complex extracts (EBLCE) were applied to extend the shelf life of the Bombay duck (Harpadon nehereus). The changes of quality indicators, including total viable count, total volatile basic nitrogen, peroxide values, thiobarbituric acid, pH values, whiteness and the sensory scores demonstrated that combination of SAEW and EBLCE had the strongest antimicrobial and antioxidant effects. Use of the combined pretreatment extended the shelf life for approximately 12 days, while pretreatment with SAEW or EBLCE alone resulted in 8-day extension when compared with the control group. Therefore, combined pretreatment with SAEW and EBLCE could effectively keep the freshness and prolong the shelf life of the Bombay duck.
The synergistic impact of hydrogen-rich water (HRW, 394 ppb) and slightly acidic electrolyzed water (SAEW, pH of 6.25 ± 0.19) on the antioxidant metabolism of fresh-cut kiwifruit during storage was investigated (temperature: (3 ± 1) °C, humidity: 80%–85%). Compared with control group, H+S treatment increased the contents of active oxygen-scavenging enzymes (SOD, CAT, POD, and APX) and inhibited the increase of O2•− and H2O2 contents during the storage of fresh-cut kiwifruit. Meanwhile, H+S treatment could reduce the activities of the cell wall-degrading enzymes PG, PME, PL, Cx, and β-Gal, inhibit the formation of soluble pectin, delay the degradation rate of propectin, cellulose, and pseudocellulose, and maintain higher fruit hardness and chewability. The results showed that H+S treatment could enhance free radical scavenging ability and reduce the cell wall metabolism of fresh-cut kiwifruit, maintaining the good texture found in fresh-cut fruit.
The aim of this study was to investigate the effect of slightly acidic electrolyzed water (SAEW) and ultrasound (US) combination on the inactivation of Vibrio parahaemolyticus in vitro and in fish samples. The bacterial log reductions caused by the US and SAEW treatment for 15 min were 0.99 and 2.63 log CFU/mL in vitro, respectively, while SAEW‐US combination achieved a 3.10 log reduction. MTT assay and protein leakage test showed that SAEW‐US combination impaired cell viability and damaged cell membrane. In addition, compared to the US or SAEW treatment, SAEW‐US combination induced higher reactive oxygen species (ROS) production, more apoptotic cells, and severer damage in bacterial cells. In spiked sliced tilapia samples, SAEW‐US combination caused about 2 log reduction of inoculated pathogen. In conclusion, these findings demonstrate that SAEW‐US combination could be potentially developed as an alternative strategy to control Vibrio parahaemolyticus contamination in aquatic foods.
Great deal pathogenic bacteria and malodorous gases are hidden in municipal solid waste (MSW), which poses excellent environmental sanitation risks for sanitation workers and residents, and preventive measures should be implemented. In this study, the simultaneous annihilation of microorganisms and volatile organic compounds (VOCs) with slightly acidic electrolyzed water (SAEW) was investigated in an MSW storage room of a residential community in Shanghai, China. The microbial population of airborne, surfaces and handles of waste bins, hands of sanitation workers and the main components of VOCs were measured. The results indicated that the bacterial reduction efficiencies of SAEW with an available chlorine concentration (ACC) of 50–100 mg/L on surfaces and handles of waste bins and sanitation workers’ hands were 22.7%–84.1%. Also, SAEW effectively reduced the average population of airborne bacteria and fungi by 358 and 378 colony-forming units (CFU)/m³ and decreased the detection rates of coliforms by 14.2%–51.9%. The concentrations of most VOCs were reduced by 21.4%–88.3% after spraying SAEW. And the accumulated values of carcinogenic and noncarcinogenic risks also tended to decrease with spraying SAEW. These findings imply that SAEW has significant application potential to control environmental sanitation risks in MSW storage rooms.
Non-thermal plasma (NTP) is an advanced technology that gains extensive attention due to its capacity for the food decontamination. Recently, plasma-activated water (PAW), a product of NTP reacting with water which is containing a rich diversity of highly reactive oxygen species (ROS) and reactive nitrogen species (RNS), is considered to be the key player in food decontamination from both biological and chemical sources. Despite the recent exciting developments in this field, there presently is no typical review which specifically focuses on the comprehensive effects of PAW on food safety and quality. Although the PAW applications in biological decontamination have been well-known, a complete analysis of the most recent developments of PAW technology such as PAW combined with other treatments, PAW applications in chemical degradation and as curing agents is still missing. Thus, this review focuses on applications of PAW for enhanced food safety (both biological safety and chemical safety) according to the most up-to-date studies. Further, the subsequent effects on food quality (chemical, physical, and sensory properties) are discussed here in detail. In addition, several recent trends of PAW developments such as curing agents, thawing media, preservation of aquatic products, and the synergistic effects of PAW combined with other traditional treatments are also presented. Finally, this review also outlines several limitations posed by PAW treatment, leading to offer several future research directions and challenges that may stimulate the translation of these technologies into real-life applications.
Microbiological contamination of vegetables leading to foodborne disease is a serious public health problem. Slightly acidic electrolyzed water (SAEW) and ultraviolet-light emitting diode (UV-LED) are considered to have good bactericidal effect. However, the limitations of SAEW in application include its instability and the great dependence on equipment and that of UV-LED remains poorly characterized. To improve decontamination efficiency and explore the combined bactericidal efficacy, the coriander, immerged in different concentration SAEW in advance, were studied under various UV-LED intensity: 80, 160, 240 μW/cm2 for different times. Additionally, the coriander was evaluated for total viable counts and general quality. The result showed that UV-LED-SAEW combined treatment has better decontamination efficiency than that of single factor and the inactivation efficacy was related to the concentration of SAEW, intensity of UV-LED and their treating time. The 240 μW/cm² UV-LED irradiation for 30 min combined with SAEW (ACC of 60 mg/L) 5-min-washing led to 2.72 log CFU/g Salmonella reduction and 2.42 log CFU/g E. coli reduction. The SAEW and UV-LED treatment cause no significant negative effect on overall coriander quality and prolonged the shelf-life of coriander. UV-LED with SAEW pretreatment shows potential for reducing foodborne pathogens on coriander without effects on its quality.
BACKGROUND
Central kitchen is a new trend in food industry where centralized preparation and processing of fresh foods as well as distribution of finished or semi‐finished products to catering chains or related units take place. Fresh foods processed by a central kitchen mainly include fruit and vegetables, meat, aquatic products and edible fungi; these foods have high water activities and thermal sensitivities and must be processed with care. Appropriate pretreatments are generally required for these food materials; typical pretreatment processes include cleaning, enzyme inactivation, disinfection as well as packaging and coating. To improve the working efficiency of a central kitchen, novel efficient pretreatment technologies are needed.
RESULTS
This article systematically reviews various high‐efficiency pretreatment technologies for fresh foods. These include ultrasonic cleaning technologies, physical‐field enzyme inactivation technologies, non‐thermal disinfection technologies as well as modified atmosphere packagings and coatings. Mechanisms, applications, influencing factors, advantages and disadvantages of these technologies, which can be used in a central kitchen, are outlined and discussed.
CONCLUSION
Possible solutions to problems related to central kitchen food processing, including low cleaning efficiency and automation feasibility, high nutrition loss, high energy consumption and short shelf life of products are addressed. These should lead us to the next step of fresh food processing for highly demanding modern society.
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This research aims to study on the disinfection efficiency of Hoa Sen medical instrument sterilizing equipment based on the application of ECA technology at General Hospital and Obstetrics and Paediatrics Hospitals in Tra Vinh. Disinfection using ECA technology is a method that does not require the introduction of special oxidizing agents except of water and salt. ECA solution - Anolyte solution has very strong oxidants, which oxidize components such as protein, lipid, etc. (usually of the bacterial cell membrane) that make the cell membrane decomposed, reducing 77−93% of the respiratory ability of bacterial cells, weakening them and eventually being destroyed. Hoa Sen medical instrument sterilizing equipment has a similar construction form as a regular double washing table with two wash basins, wherein one sink with a faucet which produces purified water, while other one has a faucet that gives anolyte solution for sterilization. Both faucets are based on a touch support. At the bottom of the sink an anolyte solution production system was installed. Valorization of the disinfection ability of the Hoa Sen medical instrument sterilizing equipment was based on the determination of the number of microorganisms on the surface of the instrument before and after being soaked with an antiseptic washing table. Microbiological criteria are the number of aerobic bacteria, E. Coli and Coliforms. Analytical samples were quantified by culture method on agar plates. Analysis of total aerobic bacteria, E. Coli and Coliforms bacteria according to Vietnam Standard TCVN 4884:2015, TCVN 6846:2007 and TCVN 6848:2007, respectively. The results showed that bacterial removal efficiency was elevated with a novel Hoa Sen sterilizing equipment anolyte. In laboratory scale, E. Coli and Coliforms bacteria with a density of 105 CFU/mL were completely removed in 30 sec contact with an anolyte solution of 300 mg/L active chlorine concentration. In hospital scale, the removal efficiency of total aerobic bacteria on the surface of medical instruments after surgery was 99% for one minute disinfection time. For E. Coli and Coliforms bacteria, the results of the analysis were not detected in both cases before and after sterilization.
Neutral Electrolyzed Water (NEW) was tested in vitro and on artificially contaminated eggs against Salmonella enterica subsp. enterica or Escherichia coli. The antibacterial effect was measured 30 s after treatment. NEW microbicide activity results were compared against 2% citric acid and 0.9% saline solutions. NEW caused an in vitro decrease in Salmonella titers by ˃5.56 Log10 CFU mL-1 and in artificially contaminated eggs by ˃1.45 Log10 CFU/egg. When it was tested against E. coli, it decreased in vitro bacterial titers by ˃3.28 Log10 CFU mL-1 and on artificially contaminated eggs by ˃6.39 Log10 CFU/egg. The 2% citric acid solution caused an in vitro decrease of 0.4 Log10 CFU mL-1 of Salmonella and E. coli and on eggs artificially contaminated with E. coli or Salmonella there was a decrease of 0.06 and 0.62 Log10 CFU/egg respectively. We evaluated egg cuticle integrity by scanning electron microscopy after treatments with evaluated solutions; the 2% citric acid solution caused damage to the cuticle and exposed eggshell pores and no interaction of NEW or NaCl with the cuticle was observed. NEW treatment showed a fast-bactericidal effect in vitro and table eggs.
Acidic electrolyzed water (AEW) is used for the surface sterilization of fresh vegetables owing to its high bactericidal activity and food safety. AEW is also a specified agricultural chemical for the protection of vegetables from various disease. In this study, we demonstrated that a mist cooling system, including AEW, effectively reduced viable bacteria counts on the surface of eggplant. It was revealed that the mist cooling system including AEW is useful for labor-saving, hygiene control of farm products at the production stage.
Foodborne pathogens can survive as the state of sublethal injury in adverse environments and recover physiological function and virulence under suitable conditions. Slightly acidic electrolyzed water (SAEW) is a non-thermal treatment to decontaminate in food industry and can induce sublethal injury. However, sublethal injury induced by SAEW and recoveries of different pathogens have not been fully investigated. In this study, it was observed that sublethally injured L. monocytogenes and E. coli O157:H7 cells widely persisted after exposure to different SAEW treatments (both of two pathogens: volumes of SAEW 1–10 ml, concentrations of SAEW 25%–100%; L. monocytogenes: treatment time 30–180 s, E. coli O157:H7: treatment time 15–90 s). And the highest recovery ratio of injured L. monocytogenes or E. coli O157:H7 was observed in TSB-YE or TSB and these cells were completely recovered within 60 min or 2.5 h, respectively. The recovery ratio of SAEW-injured L. monocytogenes and E. coli O157:H7 increased as recovery temperature increasing (4–37 °C). Mg, Ca and Zn cations significantly improved the recovery ratios of both two pathogens, but Fe and Mn cations had negative effects on recovery. Moreover, the concentrations of cations (0.5–8 mM) affected repair. The most appropriate concentration of Mg, Ca or Zn cations improving the repair of injured L. monocytogenes was 1 mM, 8 mM or 0.5 mM, respectively. The recovery ratio of injured E. coli O157:H7 increased with the concentrations of Mg, Ca and Zn cations increasing. The understanding of SAEW-injured and resuscitated conditions of L. monocytogenes and E. coli O157:H7 can avoid the occurrence of injured cells in food processing and develop a medium for detecting injured pathogens.
Flow-through configuration for electrochemical disinfection is considered as a promising approach to minimize the formation of toxic byproducts and energy consumption via the enhanced convective mass transport as compared with conventional flow-by one. Under this hydrodynamic condition, it is essential to ascertain the effect of sequential electro-redox processes with the cathode/anode then anode/cathode arrangements on disinfection performance. Here, carbon fiber felt (CFF) was utilized to construct two flow-through electrode systems (FESs) with sequential reduction-oxidation (cathode-anode) or oxidation-reduction (anode-cathode) processes to systematically compare their disinfection performance towards a model Escherichia coli (E. coli) pathogen. In-situ sampling and live/dead backlight staining experiments revealed that E. coli inactivation mainly occurred on anode via an adsorption-inactivation-desorption process. In reduction-oxidation system, after the cathode-pretreatment, bulk solution pH increased significantly, leading to the negative charge of E. coli cells. Hence, E. coli cells were adsorbed and inactivated easily on the subsequent anode, finally resulting in its much better disinfection performance and energy efficiency than the oxidation-reduction system. Application of 3.0 V resulted in ~6.5 log E. coli removal at 1500 L m-2 h-1 (50 mL min-1), suggesting that portable devices can be designed from CFF-based FES with potential application for point-of-use water disinfection.
Electrolyzed water (EW) considered as a novel broad-spectrum and high-performance bactericide has gained immense popularity over the last few decades. It offers several advantages over other sanitizers for sanitation of both food contact and noncontact surfaces, such as safety, effective disinfection, easy operation, relatively inexpensive, and environmentally friendly. EW can be produced by electrolyzing soft tap water with sodium chloride as the chemical additive. Different producing equipment and parameters greatly influence the types and properties of EW. During production period, preparation settings are vital factors on the basic properties of EW (available chlorine concentration (ACC), pH, and oxidization reduction potential (ORP)) and then influence its inactivation efficiency, including current, water flow rate, salt/acid concentration, electrolyte and electrode, water temperature and hardness, storage environments, and so on. This chapter provides an overview of the production, properties, types of EW, as well as a section on its advantages and disadvantages.
Air quality has a direct influence on the health, welfare and performance of animals as well as
on the health of farm workers undertaking different tasks in livestock buildings. Furthermore, air
pollutants emitted from livestock buildings can reduce air, water and soil quality and potentially
undermine the health of nearby residents. There is ample evidence that the respiratory health of
various livestock species can be compromised by poor air quality. High concentrations of noxious
gases, dust and airborne microorganisms might reduce production efficiency and the general
welfare of farm animals. In some herds, a large portion of the lungs of slaughter pigs may show
signs of acute or chronic pneumonia, pleuritis or other respiratory diseases. In broilers, birds with
lung lesions account for about 30% of all rejections at meat inspection.
Farm workers can be exposed to a range of noxious gases in animal buildings and above slurry
pits, causing illness and, in some exceptional cases, mortality through suffocation or poisoning
during agitation of slurry that can release toxic hydrogen sulfide gas. Long-term exposure to
particulates in pig and poultry buildings might affect the respiratory health of farm workers.
Dust in animal buildings contains many biologically active substances such as bacteria, fungi,
endotoxins and residues of antibiotics (as a result of veterinary treatments) that are suspected to
be hazardous to human health. Epidemiological studies have demonstrated that working in pig
confinement buildings is associated with symptoms of chronic bronchitis (cough and phlegm),
asthma-like symptoms such as wheezing and shortness of breath during work. Exposure to dust in
piggery buildings causes an immediate inflammation of the airways in many individuals. Longterm
studies indicate that work inside pig buildings doubles or triples the incidence of respiratory
symptoms.
Residents living close to livestock buildings can be exposed to dust and bacteria, which might
produce negative health effects. It is well-documented (within and outside of this book) that
livestock farming is a source of many different emissions. Airborne emissions include ammonia,
methane, nitrous oxide, and particulates such as dust and microorganisms. In addition, other
potentially harmful substances such as heavy metals, antibiotic residues and components of disinfectants
might be emitted from livestock building via air ventilation, slurry and/or solid manure.
The impacts of these emissions are potentially damaging to ecosystems, even at considerable
distances away from the farms. Livestock farming also contributes significantly to total anthropogenic
greenhouse gas emissions, which are thought by many to influence climate, and many
countries have now undertaken steps to reduce these emissions.
This book concentrates on the nature and amounts of aerial pollutants arising from livestock
production and their impacts on the health and welfare of farm animals, and the workforce, as well
as on the environment. We hope that this book will be useful for farming professionals, academics,
students, policy makers, business leaders, regulatory bodies and agricultural consultants.
The use of electrolyzed water in the washing of fruits and vegetables is a promising alternative treatment to chlorine washing. Electrolyzed water washing, is safer, healthier, reduces cleaning times, and is ready to handle. In recent years, food poisoning outbreaks which are caused by bacteria with acid tolerance response in fruits and vegetables has increased. In addition, pathogen produce cases and outbreaks linked to fresh fruits and vegetables, such as cantaloupes, strawberries, fruit salads, spinach, lettuce, celery, and tomatoes has been encountered. Nowadays, the necessity of effective and healthy decontamination processes has gained more importance. The aim of this review is to offer a complete view about electrolyzed water, its classifications and applications. Decontamination results of extant literature of electrolyzed water were also presented. Also, the effects and results of electrolyzed water decontamination on the microbial counts of fresh fruits and vegetables compared with different sanitizing agents have been summarized.
We investigated the effect of sodium alginate hydrosols (1%) with 0.2% of NaCl treated with direct electric current (DC) used as a coating on microbial (Total Viable Counts, Psychrotrophic bacteria, yeast and molds, Lactic acid bacteria, Enterobacteriaceae), physiochemical (pH, lipid oxidation, antioxidant activity, weight loss, color) and sensory properties of skinned pork sausages or with artificial casing stored at 4 °C for 28 days. Moreover, the cytotoxicity analysis of sodium alginate hydrogels was performed. The results have shown that application of experimental coatings on the sausage surface resulted in reducing all tested groups of microorganisms compared to control after a 4-week storage. The cytotoxicity analysis revealed that proliferation of RAW 264.7 and L929 is not inhibited by the samples treated with 200 mA. Ferric reducing antioxidant power (FRAP) and free radical scavenging activity (DPPH) analyses showed that there are no significant differences in antioxidant properties between control samples and those covered with sodium alginate. After 28 days of storage, the highest value of thiobarbituric acid-reactive substances (TBARS) was noticed for variants treated with 400 mA (1.07 mg malondialdehyde/kg), while it was only slightly lower for the control sample (0.95 mg MDA/kg). The obtained results suggest that sodium alginate treated with DC may be used as a coating for food preservation because of its antimicrobial activity and lack of undesirable impact on the quality factors of sausages.
This study combined plate counting method and fluorescent technique (membrane integrity and potential, intracellular enzyme activity, and intracellular ROS level) to investigate the lethal and sublethal effects of slightly acidic electrolyzed water (SAEW) on Escherichia coli and Staphylococcus aureus. Also, the inactivation mechanism of SAEW was further explored through multiple cell targets (outer membrane and intracellular components). The results within 30 s SAEW treatment displayed 6.02 and 5.83 log reductions obtained for E. coli and S. aureus, respectively. The maximum sublethally injured cell proportions induced by SAEW exposure were 0.34 and 0.40 log10 CFU/mL for E. coli and S. aureus, respectively. According to the data from experiments of various acting cellular sites by fluorescent techniques, SAEW damaged the microbial membrane integrity and membrane potential severely. Also, it posed inactivation effect on the activity of intracellular esterase enzymes. Therefore, SAEW showed disinfection behavior with multiple cellular targets, including both cell barriers and intracellular components. Furthermore, SAEW did not result in accumulation of reactive oxygen species (ROS) inside microbial cell, indicating SAEW conducted a ROS-independent behavior on microbial inactivation and the chemical oxidants (e.g., hypochlorous acid) played major role in microbial intracellular oxidation processing. The result in this study will help to further understand the disinfection mechanism underlying SAEW on microorganisms and make SAEW inactivation targets more explicit.
The objective of this study was to evaluate the efficacy of tap water (TW), commercial electrolyzed water (EW), and a commercial acid-based sanitizer (AS) in preventing cross-contamination of cantaloupe during processing in retail settings. A whole cantaloupe was dip-inoculated with a cocktail of Salmonella or L. monocytogenes to achieve approximately 5 log CFU/cm². One inoculated and two non-inoculated whole cantaloupes were treated in 76 L of TW, EW (free chlorine: 50-60 ppm), or AS (pH 2.8, combination of lactic acid and phosphoric acid) for 5 min. Subsequently, fresh-cut cantaloupe flesh from the inoculated and non-inoculated cantaloupes were soaked together in 76 L of TW, EW, or AS for 90 s. EW treatment resulted in an approximately 1.5 log reduction in both Salmonella and L. monocytogenes on the rind of whole cantaloupe, which was significantly greater than with the TW treatment (0.5 log reduction) (P<0.05). Cross-contamination of non-inoculated whole cantaloupes occurred when washed with inoculated whole cantaloupe in TW (four of four cantaloupes positive for Salmonella and L. monocytogenes) or AS (four of four cantaloupes positive for Salmonella and two of four positive for L. monocytogenes). Cross-contamination did not occur when whole cantaloupes were washed in EW. Additional washing of mixed fresh-cut cantaloupe flesh from the inoculated and non-inoculated cantaloupes prepared after washing of whole cantaloupes demonstrated that the EW treatment reduced the likelihood of cross-contamination compared with TW and AS. No viable Salmonella or L. monocytogenes were detected from 100 mL sample of EW processing water, but were detected in TW and AS (L. monocytogenes only). The addition of a sanitizing agent to water used for the processing of whole and fresh-cut cantaloupe in a retail setting is recommended to prevent cross-contamination and reduce microbial load.
The effectiveness of slightly acidic electrolyzed water (SAEW) in reducing Escherichia coli, Salmonella typhimurim, Staphylococcus aureus or bacterial mixtures on stainless steel surfaces was evaluated and compared its efficacy with composite phenol solution for reducing total aerobic bacteria in animal transport vehicles. Stainless steel surfaces were inoculated with these strains individually or in a mixture, and sprayed with SAEW, composite phenol, or alkaline electrolyzed water for 0.5, 1, 1.5 and 2 min. The bactericidal activity of SAEW increased with increasing available chlorine concentration and spraying duration. The SAEW solution of 50 mg l⁻¹ of available chlorine concentration showed significantly higher effectiveness than composite phenol in reducing the pathogens on stainless steel surfaces (P < 0.05). Complete inactivation of pathogens on stainless steel surfaces were observed after treatment with alkaline electrolyzed water followed by SAEW at 50 mg l⁻¹ of available chlorine concentration for 2 min or alkaline electrolyzed water treatment followed by SAEW treatment at 90 mg l⁻¹ of ACC for 0.5 min. The efficacy of SAEW in reducing total aerobic bacteria in animal transport vehicles was also determined. Vehicles in the disinfection booth were sprayed with the same SAEW, alkaline electrolyzed water and composite phenol solutions using the automatic disinfection system. Samples from vehicle surfaces were collected with sterile cotton swabs before and after each treatment. No significant differences in bactericidal efficiency were observed between SAEW and composite phenol for reducing total aerobic bacteria in the vehicles (P > 0.05). SAEW was also found to be more effective when used in conjunction with alkaline electrolyzed water. Results suggest that the bactericidal efficiency of SAEW was higher than or equivalent to that of composite phenol and SAEW may be used as effective alternative for reducing microbial contamination of animal transport vehicles.
Electrolyzed water (EW) has gained immense popularity over the last few decades as a novel broad-spectrum sanitizer. EW can be produced using tap water with table salt as the singular chemical additive. The application of EW is a sustainable and green concept and has several advantages over traditional cleaning systems including cost effectiveness, ease of application, effective disinfection, on-the-spot production, and safety for human beings and the environment. These features make it an appropriate sanitizing and cleaning system for use in high-risk settings such as in hospitals and other healthcare facilities as well as in food processing environments. EW also has the potential for use in educational building, offices, and entertainment venues. However, there have been a number of issues related to the use of EW in various sectors including limited knowledge on the sanitizing mechanism. AEW, in particular, has shown limited efficacy on utensils, food products, and surfaces owing to various factors, the most important of which include the type of surface, presence of organic matter, and type of tape water used. The present review article highlights recent developments and offers new perspectives related to the use of EW in various areas, with particular focus on the food industry. From an industrial viewpoint, this publication can be used for the comparison and improvement of electrolyzed water (EW) generators. From a scientific standpoint, this publication can help in understanding the role of various parameters and can provide insight into EW producing systems and its applications for further research and development.
Slightly acidic electrolyzed water (SAEW) has been recognized as an effective bactericidal agent with free chlorine, but its limitations include its instability and its great dependence on equipment. Newly developed circulating electrolyzed water (CEW) with a higher available chlorine concentration (ACC) could successfully overcome these limitations. In this study, SAEW (ACC of 20 mg/L), CEW1 (ACC of 200 mg/L), and CEW2 (ACC of 20 mg/L) were evaluated for changes in properties (pH, oxidization reduction potential [ORP], and ACC) during storage in open or closed glass bottles under light or dark conditions at room temperature (approximately 20 °C) and after washing pork and lettuce. Additionally, the washed pork and lettuce were evaluated for total viable counts, pH and general appearance. The results showed that CEW1 with a higher ACC has better stability than SAEW with a lower ACC for the storage and washing experiments, and CEW still remained stable after dilution with distilled water. The property indices of EW were greatly affected for the pork-washing experiments compared with the lettuce-washing experiments, probably due to the existence of alkaline and organic materials on the surface of pork. Furthermore, EWs were more effective for inactivating microbes in lettuce than in pork, while there was no significant difference in tissue pH and the general appearance of pork and lettuce. These findings indicated that CEW with a higher ACC shows potential for reducing foodborne pathogens on pork and lettuce without effects on their physicochemical characteristics, and it can be applied in a diluted form.
Postoperative endophthalmitis is the most serious complications of ophthalmic surgeries. Conjunctival sac disinfection is currently recognized as an effectively important way to reduce the risk of endophthalmitis. At present, there are some disinfectants has been used in clinic or in the researches: mercury agent, gentamicin, povidone iodine and acid electrolytic water. All kinds of disinfectants play the role of disinfection by different ways. Povidone iodine is the most widely used conjunctival sac disinfectant. Mercurial and gentamicin have been rarely used because they pollute the environment, are easy to cause drug resistant bacteria, localized side reactions and so on. The acid electrolyte water is not used in clinic at present. With the popularization and development of the ophthalmic surgeries, the ophthalmologists have become more and more concerned about the postoperative eye comfort, the research and application of conjunctival sac disinfectant in the future will continue to be updated and developed.
The prepared acidic electrolyzed water (AEW) coating ice was investigated for its antibacterial activity and application in frozen shrimp (Litopenaeus vannamei). The results indicated that; 1) The AEW coating ice significantly reduced total numbers of bacteria and Staphylococcus aureus in frozen shrimp meat under -18°C frozen conditions. 2) The content of TVBN in frozen fresh and cooking shrimp meat were 18.96 mg/100 g and 13.86 mg/100 g after 80 day storage, which were coated with the distilled water. While, the content in frozen fresh and cooking shrimp meat were only 11.25 mg/100 g and 8.52 mg/100 g, which were coated with the AEW ice. 3) There no significant difference was noticed in lightness, texture and volatile flavor characteristics of the frozen shrimp meat between the distilled water and AEW ice treatment. 4) The growth of microorganism and the hydrolysis of shrimp muscle protein were significantly inhibited by the slowly released effective chlorine and highly oxidation reduction action. The study can lay the foundation for developing a new method of ice coating, and further provide technological support for the product of frozen shrimp.
The possibility of washing fresh‐cut vegetables with neutral (NEW) and acidic (AEW) electrolyzed water instead of highly chlorinated solution was investigated. The decontamination efficacy was tested in vitro against Pseudomonas fluorescens, which is a typical inhabitant of leafy vegetables. The antibacterial efficacy of NEW and AEW was highly dependent on pH solution. NEW and AEW that were adjusted to a pH analogous to that of salad (6.5) completely inactivate P. fluorescens at 30 mg/L free chlorine concentration. The same result was achieved by sodium hypochlorite aqueous solution at a much higher free chlorine concentration (150 mg/L). NEW and AEW at 30 mg/L free chlorine concentration also reduced total mesophilic count, Pseudomonas spp. and total coliforms of salad by circa 1 log cycle. Microbial loads of wastewater deriving from salad washing resulted below the detection limit.
Practical Applications
Electrolyzed water can be exploited as a sanitizing washing agent in the fresh‐cut industry allowing to replace conventional chlorination of washing water with highly concentrated NaOCl. Thus, it would be possible to guarantee an analogous decontamination efficacy and decrease the overall presence of potentially toxic chlorine compounds in wastewater. This would contribute to meet the global requirement of reducing the water footprint of industrial washing and reduce the use of harmful disinfection solutions.
Slightly acidic electrolyzed water (SAEW) with pH 5.0-6.5 is produced by electrolysis of dilute hydrochloric acid or salt solution in a chamber without membrane. SAEW can effectively kill various pathogenic bacteria as one of the most potential green disinfectants. However, SAEW is susceptible to be exposed to time, air, and illumination etc. To study SAEW during storage and disinfection, the variations of pH value, oxidation-reduction potential (ORP) and available chlorine concentration (ACC) were analyzed under different storage temperatures (25°C, 30°C, 35°C, 40°C, and 50°C) for 12days. Furthermore, variations in ACC during Escherichia coli (ATCC 25922) disinfection were investigated. The results showed that the pH increased, but the ORP and ACC decreased during storage. When SAEW was stored in a transparent bottle at 25°C for 12 days, the ACC of SAEW was decreased from 20.53 mg/L to 5.06 mg/L, and the ORP of SAEW was also decreased from 821 mv to 641 mv, while pH was increased from 6.06 to 7.45 in the same condition. Variations of ACC, ORP, and pH in a brown bottle under same stored temperatures had a similar tendency. When SAEW was stored in a brown bottle at 25°C for 12days, the ACC of SAEW was also decreased and the ORP of SAEW was decreased from 821mv to 652 mv, while pH was increased from 6.06 to 7.38. The higher the stored temperature was, the quicker ACC, ORP, and pH of SAEW decayed during storage. SAEW was stored in a transparent bottle at 50°C for 12days, and the ACC of SAEW was decreased from 20.53 mg/L to 0.10 mg/L and the ORP from 821 mv to 641 mv, while pH was increased from 6.06 to 8.11in the same condition. Similarly, when SAEW was stored in a brown bottle at 50°C for 12days, the ACC of SAEW was decreased from 20.53 mg/L to 0 and the ORP from 821 mv to 583 mv, while pH was increased from 6.06 to 8.03 in same condition. The same tendency of ACC was also found during E. coli disinfection, but the decay of ACC was quicker than it was presented during storage. The ACC of SAEW was reduced by 15.05 mg/L after SAEW with ACC of 25.13 mg/L was used to disinfect for 25 min., compared with the above storage condition for five days. The decay kinetics models of the ACC in SAEW during storage and disinfection were established and the correlation coefficients were above 0.90. The temperature and duration of storage and disinfection had significant impacts on the physicochemical properties of SAEW. As the stored time prolonged, the ACC and ORP of SAEW was decreased while pH increased. The higher the stored temperature was, the larger the variation of amplitude of ACC, ORP, and pH of SAEW. The decay of ACC was quicker during disinfection than it was presented during storage and active chlorine needed to be expended during the disinfection process. The decay of ACC followed first-order kinetics during the storage and disinfection process, and the values of the kinetic parameters during the storage process were higher than it were presented during the disinfection process, and the value of k' of storage and disinfection was 0.108 (±0.044) and 0.043 (±0.005) respectively under the condition of ACC of 25.13 mg/L at 25°C.
The stability of Slightly Acidic Electrolyzed Water (SAEW) on storage was evaluated. SAEW samples of known initial Oxidation Reduction Potential (ORP, mV), pH and available chlorine concentration (ACC, mg/L) were stored at and ACC were respectively maintained at 900-1000mV, 5-6.5 and 10-30mg/L. SAEW was further evaluated for its microbial inactivation effectiveness on the aerobic microflora present on spinach (Spinacia oleracea L.) expressed as aerobic plate count (APC) and was compared to Sodium hypochlorite (NaOCl) solution. The decontamination was done by dipping spinach samples with or without a pre-washing step into treatment solution for 5min. SAEW (pH 5.5, 25mg/L ACC) achieved a significantly higher microbial reduction than NaOCl solution (pH 9.9, 103mg/L ACC). While pre-washing of spinach in running tap water for 5min increased the microbial reduction by SAEW from 1.3 logo colony forming units (CFU)/g to more than 2 log10 CFU/g at 5min contact time, increasing exposure time did not significantly affect its antimicrobial effectiveness on spinach aerobic microflora.
Raman spectroscopic analysis has been used to identify the chemical species that exist in aqueous chlorine solution. The pH dependence of the Raman spectra obtained indicates that there :is an equilibrium among hypochlorite ion, hypochlorous acid and chlorine. Bactericidal activities of the acidic electrolyzed water, which is generated by electrolysis of an aqueous NaCl solution, were evaluated in the pH range 2-9 against Escherichia coli K12 and Bacillus subtilis PCI219 by a semi-quantitative bioassay. The maximum activity was observed between pH 4 and 5 in both bacteria. The Raman and the ultraviolet spectroscopic data, along with chemical analysis data, were used to conclude that the bactericidal activity is quantitatively correlated to the concentration of hypochlorous acid in solution.
The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichia coli O157:H7 and Listeria monocytogenes on lettuce. After surface inoculation, each leaf was immersed in 1.5 L of EO or acidified chlorinated water for 1 or 3 min at 22 °C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log10 CFU per lettuce leaf for 3 min treatments, respectively (p < 0.05). However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p > 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.
Washing whole and cut produce by dipping or submerging in chlorinated water has a sanitizing effect, although reduction in microbial populations is minimal and is usually less than 100-fold. A study was undertaken to evaluate the efficacy of a spray application of chlorine in killing Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, yeasts and molds, and total aerobic mesophilic microorganisms on whole apples, tomatoes, and lettuce leaves. Inoculated produce was treated (sprayed and then soaked) with water (control) or solutions containing 200 or 2,000 ppm of chlorine for 0, 1, 3, 5, or 10 min, rinsed with sterile water, and analyzed for populations (CFU/cm2) of target microorganisms. Compared to the control treatment, further reductions in numbers of pathogens of 0.35 to 2.30 log CFU/cm2 were achieved by treatment with chlorine. Chlorine was generally more effective at 2,000 ppm than at 200 ppm. Inactivation of microorganisms occurred essentially within 1 min after application of chlorine. These reductions are significant relative to populations of pathogenic microorganisms that may be present on produce. Spray application of chlorine to raw produce at food service or household levels may be a suitable, and more convenient, alternative to treatment by dipping or submersion.
One milliliter of culture containing a five-strain mixture of Escherichia coli O157:H7 (approximately 10(10) CFU) was inoculated on a 100-cm2 area marked on unscarred cutting boards. Following inoculation, the boards were air-dried under a laminar flow hood for 1 h, immersed in 2 liters of electrolyzed oxidizing water or sterile deionized water at 23 degrees C or 35 degrees C for 10 or 20 min; 45 degrees C for 5 or 10 min; or 55 degrees C for 5 min. After each temperature-time combination, the surviving population of the pathogen on cutting boards and in soaking water was determined. Soaking of inoculated cutting boards in electrolyzed oxidizing water reduced E. coli O157:H7 populations by > or = 5.0 log CFU/100 cm2 on cutting boards. However, immersion of cutting boards in deionized water decreased the pathogen count only by 1.0 to 1.5 log CFU/100 cm2. Treatment of cutting boards inoculated with Listeria monocytogenes in electrolyzed oxidizing water at selected temperature-time combinations (23 degrees C for 20 min, 35 degrees C for 10 min, and 45 degrees C for 10 min) substantially reduced the populations of L. monocytogenes in comparison to the counts recovered from the boards immersed in deionized water. E. coli O157:H7 and L. monocytogenes were not detected in electrolyzed oxidizing water after soaking treatment, whereas the pathogens survived in the deionized water used for soaking the cutting boards. This study revealed that immersion of kitchen cutting boards in electrolyzed oxidizing water could be used as an effective method for inactivating foodborne pathogens on smooth, plastic cutting boards.
The efficacy of electrolyzed oxidizing water for inactivating Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes was evaluated. A five-strain mixture of E. coli O157:H7, S. enteritidis, or L. monocytogenes of approximately 10(8) CFU/ml was inoculated in 9 ml of electrolyzed oxidizing water (treatment) or 9 ml of sterile, deionized water (control) and incubated at 4 or 23 degrees C for 0, 5, 10, and 15 min; at 35 degrees C for 0, 2, 4, and 6 min; or at 45 degrees C for 0, 1, 3, and 5 min. The surviving population of each pathogen at each sampling time was determined on tryptic soy agar. At 4 or 23 degrees C, an exposure time of 5 min reduced the populations of all three pathogens in the treatment samples by approximately 7 log CFU/ml, with complete inactivation by 10 min of exposure. A reduction of >/=7 log CFU/ml in the levels of the three pathogens occurred in the treatment samples incubated for 1 min at 45 degrees C or for 2 min at 35 degrees C. The bacterial counts of all three pathogens in control samples remained the same throughout the incubation at all four temperatures. Results indicate that electrolyzed oxidizing water may be a useful disinfectant, but appropriate applications need to be validated.
To better quantify the impact of foodborne diseases on health in the United States, we compiled and analyzed information from multiple surveillance systems and other sources. We estimate that foodborne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. Known pathogens account for an estimated 14 million illnesses, 60, 000 hospitalizations, and 1,800 deaths. Three pathogens, Salmonella, Listeria, and Toxoplasma, are responsible for 1,500 deaths each year, more than 75% of those caused by known pathogens, while unknown agents account for the remaining 62 million illnesses, 265,000 hospitalizations, and 3,200 deaths. Overall, foodborne diseases appear to cause more illnesses but fewer deaths than previously estimated.
This study investigates the properties of electrolyzed oxidizing (EO) water for the inactivation of pathogen and to evaluate the chemically modified solutions possessing properties similar to EO water in killing Escherichia coli O157:H7. A five-strain cocktail (10(10) CFU/ml) of E. coli O157:H7 was subjected to deionized water (control), EO water with 10 mg/liter residual chlorine (J.A.W-EO water), EO water with 56 mg/liter residual chlorine (ROX-EO water), and chemically modified solutions. Inactivation (8.88 log10 CFU/ml reduction) of E. coli O157:H7 occurred within 30 s after application of EO water and chemically modified solutions containing chlorine and 1% bromine. Iron was added to EO or chemically modified solutions to reduce oxidation-reduction potential (ORP) readings and neutralizing buffer was added to neutralize chlorine. J.A.W-EO water with 100 mg/liter iron, acetic acid solution, and chemically modified solutions containing neutralizing buffer or 100 mg/liter iron were ineffective in reducing the bacteria population. ROX-EO water with 100 mg/liter iron was the only solution still effective in inactivation of E. coli O157:H7 and having high ORP readings regardless of residual chlorine. These results suggest that it is possible to simulate EO water by chemically modifying deionized water and ORP of the solution may be the primary factor affecting microbial inactivation.
Effects of storage temperature (1, 5, and 10 degrees C) on growth of microbial populations (total aerobic bacteria, coliform bacteria, Bacillus cereus, and psychrotrophic bacteria) on acidic electrolyzed water (AcEW)-treated fresh-cut lettuce and cabbage were determined. A modified Gompertz function was used to describe the kinetics of microbial growth. Growth data were analyzed using regression analysis to generate "best-fit" modified Gompertz equations, which were subsequently used to calculate lag time, exponential growth rate, and generation time. The data indicated that the growth kinetics of each bacterium were dependent on storage temperature, except at 1 degrees C storage. At 1 degrees C storage, no increases were observed in bacterial populations. Treatment of vegetables with AcEW produced a decrease in initial microbial populations. However, subsequent growth rates were higher than on nontreated vegetables. The recovery time required by the reduced microbial population to reach the initial (treated with tap water [TW]) population was also determined in this study, with the recovery time of the microbial population at 10 degrees C being <3 days. The benefits of reducing the initial microbial populations on fresh-cut vegetables were greatly affected by storage temperature. Results from this study could be used to predict microbial quality of fresh-cut lettuce and cabbage throughout their distribution.
Studies have demonstrated that electrolyzed oxidizing (EO) water is effective in reducing foodborne pathogens on fresh produce. This study was undertaken to determine the efficacy of EO water and two different forms of chlorinated water (chlorine water from Cl2 and Ca(OCl)2 as sources of chlorine) in inactivating Salmonella on alfalfa seeds and sprouts. Tengram sets of alfalfa seeds inoculated with a five-strain cocktail of Salmonella (6.3 x 10(4) CFU/g) were subjected to 90 ml of deionized water (control), EO water (84 mg/liter of active chlorine), chlorine water (84 mg/liter of active chlorine), and Ca(OCl)2 solutions at 90 and 20,000 mg/liter of active chlorine for 10 min at 24 +/- 2 degrees C. The application of EO water, chlorinated water, and 90 mg/liter of Ca(OCl)2 to alfalfa seeds for 10 min reduced initial populations of Salmonella by at least 1.5 log10 CFU/g. For seed sprouting, alfalfa seeds were soaked in the different treatment solutions described above for 3 h. Ca(OCl)2 (20,000 mg/liter of active chlorine) was the most effective treatment in reducing the populations of Salmonella and non-Salmonella microflora (4.6 and 7.0 log10 CFU/g, respectively). However, the use of high concentrations of chlorine generates worker safety concerns. Also, the Ca(OCl)2 treatment significantly reduced seed germination rates (70% versus 90 to 96%). For alfalfa sprouts, higher bacterial populations were recovered from treated sprouts containing seed coats than from sprouts with seed coats removed. The effectiveness of EO water improved when soaking treatments were applied to sprouts in conjunction with sonication and seed coat removal. The combined treatment achieved 2.3- and 1.5-log10 CFU/g greater reductions than EO water alone in populations of Salmonella and non-Salmonella microflora, respectively. This combination treatment resulted in a 3.3-log10 CFU/g greater reduction in Salmonella populations than the control (deionized water) treatment.
A new super-oxidized water (SOW) product, Microcyn, was tested for in vitro antimicrobial and antiviral activities. The effectiveness of this neutral-pH SOW at killing Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans in pure culture was evaluated. One millilitre (approximately 10(8)colony-forming units/mL) of each micro-organism was subjected to 9 mL Microcyn or sterile water at room temperature for 30s. Under these conditions, a log(10) reduction factor of 8 in the level of all pathogens occurred in the treatment samples. In addition, results of tests with three batches of Microcyn exposed to Bacillus atrophaeus spores for 5 min demonstrated complete inactivation of the spores within 2-3 min (log(10) reduction factor >4). The effectiveness of Microcyn in reducing human immunodeficiency virus-1 (HIV-1) on hard surfaces (glass) was also evaluated in compliance with Environmental Protection Agency requirements for virucidal claims. After exposure of the tested surfaces to Microcyn for 5 min without agitation, there was a log(10) reduction factor >3 in the viral load as measured by both cytopathic effect and antigen p24 of HIV-1 production in MT-2 cultures. Microcyn activity against adenoviral vector type 5 was also analysed under simulated laboratory in-use conditions with viral suspensions. In order to increase the sensitivity of the test, the fluorescent light emitted by AdGFP-infected cells was measured with the use of a flow cytometer. A log(10) reduction factor >3 in the viral load was achieved after a 5-min exposure to Microcyn under these strict conditions. These results show that Microcyn exerts a wide antimicrobial spectrum with major advantages over acidic SOWs, including neutral pH, lower free active chlorine (51-85 ppm) and long shelf life (1 year).
This study evaluated the efficacy of neutral electrolyzed water (NEW; 64.1 mg/liter of active chlorine) to reduce populations of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Listeria monocytogenes on plastic and wooden kitchen cutting boards. Its effectiveness was compared with that of a sodium hypochlorite solution (NaClO; 62.3 mg/liter of active chlorine). Inoculated portions of cutting boards were rinsed in either NEW or NaClO solutions, or deionized water (control). Plastic boards were rinsed for 1 min and wooden boards for 1 and 5 min. After each treatment, the surviving population of each strain was determined on the surface and in the soaking water. No significant difference (P > or = 0.05) was found between the final populations of each strain with regard to the treatment solutions (NEW or NaClO). However, a significant difference (P < or = 0.05) was revealed between surface materials after 1 min of washing. Whereas in plastic boards the initial bacterial populations were reduced by 5 log CFU/50 cm2, in wooden cutting boards they underwent a reduction of <3 log CFU/50 cm2. A 5-min exposure time yielded reductions of about 4 log CFU/50 cm2. The surviving populations of all bacteria in NEW and NaCIO washing solutions were <1 log CFU/ml after soaking both surfaces. This study revealed that NEW treatment is an effective method for reducing microbial contamination on plastic and wooden cutting boards. NEW efficacy was comparable to that of NaCIO, with the advantage of having a larger storage time.
The measurement of oxidation/reduction potential (ORP) is useful but often underutilized. A discussion of how ORP works in the disinfection process is presented.
Numerous food products owe their production and characteristics to the activities of microorganisms. Many of these, including such foods as ripened cheeses, pickles, sauerkraut, and fermented sausages, are preserved products in that their shelf life is extended considerably over that of the raw materials from which they are made. In addition to being made more shelf stable, all fermented foods have aroma and flavor characteristics that result directly or indirectly from the fermenting organisms. In some instances, the vitamin content of the fermented food is increased along with an increased digestibility of the raw materials. The fermentation process reduces the toxicity of some foods (for example, gari and peujeum), while others may become extremely toxic during fermentation (as in the case of bongkrek). From all indications, no other single group or category of foods or food products is as important as these are and have been relative to nutritional well-being throughout the world. Included in this chapter along with the classical fermented foods are such products as coffee beans, wines, and distilled spirits, for these and similar products either result from or are improved by microbial fermentation activities.
The toxicity of chlorine solutions to cells of Erwinia carotovora subsp. carotovora and conidia of Geotrichum candidum suspended in water at pH 6.0, 7.0, or 8.0 was correlated with the free chlorine concentration and oxidation-reduction potential of the solutions. The oxidation-reduction potential was directly correlated with the Log 10 of the chlorine concentration at each pH. Cells of E. c. carotovora were 50 times more sensitive to chlorine than were conidia of G, candidum, with populations of 1 × 10 7 cfu/ml and 1 × 10 7 conidia per milliliter, respectively, Populations of E. c, carotovora were reduced below detectable levels (< 10 2 cfu/ml) by approximately 0,5, 0,5, or 0,75 mg of free chlorine per liter at pH 6.0, 7.0, or 8.0, respectively. In contrast, with conidia of G. candidum, 25, 25, and greater than 30 mg/L, respectively, were required to produce a similar level of efficacy. With both organisms, population reductions were associated with higher initial oxidation-reduction potentials at pH 6.0 than at pH 8.0
External leaves of whole lettuce were found to have counts approximately 1 log cycle higher than subsequent inner leaf layers. A standard washing in tap water resulted in the removal of an average of 92.4% of the lettuce leaf microflora. Inclusion of 100 mg l−1 (pH c. 9) available free chlorine reduced the count by 97.8%. Adjusting the pH of hypochlorite solutions from c. 9 to 4.5–5.0 with inorganic or organic acids produced a 1.5–4.0 fold increase in the microbiocidal effect. Increasing the washing time in hypochlorite from 5 to 30 min did not decrease microbial numbers further whereas extended washing in tap water produced a reduction comparable to hypochlorite. Addition of a surfactant, Tween 80, to hypochlorite reduced microbial numbers by 99.6% but resulted in organoleptic differences. Failure of conventional water and hypochlorite washing to remove more of the microflora is ascribed to the survival of bacteria in protective hydrophobic pockets or folds in the leaf surface and some supportive electron microscopy evidence is presented.
Chlorination presents one of the few chemical options available to help manage postharvest decay. Electrolyzed oxidizing (EO) water, containing free chlorine, is the product of a new concept developed by scientists in Japan. The effectiveness of pear (Pyrus communis L.) immersion in EO water on the control of Bot. rot on European pear, cv. La-France, was investigated. Four independent experiments were carried out. A wound was found necessary for infection. Wounded fruit were inoculated with 20 μl spore suspension of 5×105 conidia/ml of Botryosphaeria berengeriana, incubated for 4 h, immersed in EO water, and held at 20 °C, ⩾90% relative humidity (simulated retail conditions) for ripening and disease development. No chlorine-induced phytotoxicity was observed on the treated fruit. EO water suppressed the incidence and disease severity. The minimum incidence and severity were recorded for a 10-min immersion period. This study revealed that EO water is an effective surface sanitizer.
Neutral (NEW) and acidic (AEW) electrolyzed water were stored in open or closed glass bottles under light or dark conditions at 20 °C for 30 days. The pH, oxidation–reduction potential (ORP), electrical conductivity (EC), available chlorine concentration (ACC), dissolved oxygen (DO), and bactericidal efficiency of NEW and AEW were determined during storage or before and after storage, respectively. The pH and EC of NEW and AEW remained unchanged in storage. The ORP, ACC and DO of AEW decreased 22%, 100% and 52% under open storage conditions, respectively. Light had no significant effects on the physicochemical properties of NEW (P > 0.05). Bactericidal efficiency was not markedly affected by storage conditions for NEW, but decreased significantly for AEW under open storage conditions. Electrolyzed water should be stored in closed containers or used immediately to prevent the loss of available chlorine that is one of the main contributing factors for antimicrobial activity.
The effect of electrolyzed water on total microbial count was evaluated on several fresh-cut vegetables. When fresh-cut carrots, bell peppers, spinach, Japanese radish, and potatoes were treated with electrolyzed water (pH 6.8, 20 ppm available chlorine) by dipping, rinsing, or dipping/blowing, microbes on all cuts were reduced by 0.6 to 2.6 logs CFU/g. Rinsing or dipping/blowing were more effective than dipping. Electrolyzed water containing 50 ppm available chlorine had a stronger bactericidal effect than that containing 15 or 30 ppm chlorine for fresh-cut carrots, spinach, or cucumber. Electrolyzed water did not affect tissue pH, surface color, or general appearance of fresh-cut vegetables.
A chlorine sanitizer that gives high disinfection efficacy with minimal available chlorine has a potential to be an environmentally-friendly method for disinfection of vegetables. In the present study, disinfection efficacy of slightly acidic electrolyzed water (SlAEW: pH 6.1, 20 mg/L available chlorine) produced by electrolysis for fresh cut cabbage was compared to that of sodium hypochlorite solution (NaOCl solution: pH 9.6, about 150 mg/L available chlorine). SlAEW reduced about by 1.5 log CFU/g for total aerobic bacteria and 1.3 log CFU/g for moulds and yeasts, compared to fresh cut cabbage before dipping. Statistical analysis of the results showed that the disinfectant efficacy of SlAEW was equivalent to or higher than that of NaOCl solution. Results also indicated that SlAEW under shaded and sealed conditions could keep its available chlorine during storage.
Electrolyzed oxidizing (EO) water has been regarded as a new sanitizer in recent years. Production of EO water needs only water and salt (sodium chloride). EO water have the following advantages over other traditional cleaning agents: effective disinfection, easy operation, relatively inexpensive, and environmentally friendly. The main advantage of EO water is its safety. EO water which is also a strong acid, is different to hydrochloric acid or sulfuric acid in that it is not corrosive to skin, mucous membrane, or organic material. Electrolyzed water has been tested and used as a disinfectant in the food industry and other applications. Combination of EO water and other measures are also possible. This review includes a brief overview of issues related to the electrolyzed water and its effective cleaning of food surfaces in food processing plants and the cleaning of animal products and fresh produce.
The Nernst equations between the oxidation-reduction potential (ORP), the concentration of hypochlorous acid and chlorine and the value of pH in electrolyzed oxidizing water (EOW) were developed in three parts, which were in agreement in the measured values. The role of ORP in EOW for killing Escherichia coli O157:H7 was studied. The inactivation effect of EOW on E. coh O157:H7 was also studied by spectroscopy measurements, and the inactivation mechanism was proposed. (c) 2006 Elsevier Ltd. All rights reserved.
The efficiency of slightly acidic electrolyzed water (SAEW) at different temperatures (4, 20 and 45 degrees C) for inactivation of Salmonella enteritidis and it on the surface of shell eggs was evaluated. The bactericidal activity of SAEW, sodium hypochlorite solution (NaClO) and acidic electrolyzed water (AEW) to inactivate S. enteritidis was also compared. SAEW with a pH value of 6.0-6.5 used was generated by the electrolysis of a dilute hydrochloric acid (2.4 mM) in a chamber without a membrane. Although the pH value of SAEW was greatly higher than that of AEW (pH2.6-2.7), SAEW had a comparative powerful bactericidal activity at the same available chlorine concentrations. The efficiency of SAEW for inactivation of pure S. enteritidis cultures increased with increasing the available chlorine concentration and treatment time at the three different temperatures. The S. enteritidis counts decreased to less than 1.0 log(10) CFU/ml at available chlorine of 2 mg/l and 100% inactivation (reduction of 8.2 log(10) CFU/ml) was resulted in using SAEW with available chlorine more than 4 mg/l at 4, 20 and 45 degrees C after 2 min treatment, whereas no reduction was observed in the control samples. Moreover, SAEW was also effective for inactivating the S. enteritidis inoculated on the surface of shell eggs. A reduction of 6.5 log(10) CFU/g of S. enteritidis on shell eggs was achieved by SAEW containing 15 mg/l available chlorine for 3 min, but only a reduction of 0.9-1.2 log(10) CFU/g for the control samples. No survival of S. enteritidis was recovered in waste wash SAEW after treatment. The findings of this study indicate that SAEW may be a promising disinfectant agent for the shell egg washing processing without environmental pollution.
The purposes of this study were to examine the time-related changes in pH, oxidation-reduction potential, and concentration of chlorine of electrolyzed neutral water and to evaluate the bactericidal effect of electrolyzed neutral water against bacteria from infected root canals.
Various properties of electrolyzed neutral water--pH value, oxidation-reduction potential, and concentration of chlorine--were measured at different times after storage of the water in the open state, the closed state, or the closed-and-dark state. The bactericidal effect of the various electrolyzed neutral water samples was then tested against 17 strains of bacteria, including 15 strains isolated from infected canals, as well as against 1 strain of fungus. Each bacterial or fungal suspension was mixed with electrolyzed neutral water, and the 2 substances were reacted together for 1 minute. After incubation for 1 to 7 days, the bactericidal effect of the electrolyzed neutral water was determined.
The pH value and oxidation-reduction potential of electrolyzed neutral water remained almost unchanged when the water was stored in a dark, closed container. However, the concentration of chlorine decreased from 18.4 ppm to 10.6 ppm. Electrolyzed neutral water showed a bactericidal or growth-inhibitory effect against the bacteria.
The results indicate that electrolyzed neutral water maintains a constant pH and oxidation-reduction potential when kept in a closed container without light and that it exhibits a bacteriostatic/bactericidal action against isolates obtained from infected root canals.
This study was undertaken to evaluate the efficacy of electrolyzed oxidizing (EO) and chemically modified water with properties similar to the EO water for inactivation of different types of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes and Bacillus cereus). A five-strain cocktail of each microorganism was exposed to deionized water (control), EO water and chemically modified water. To evaluate the effect of individual properties (pH, oxidation-reduction potential (ORP) and residual chlorine) of treatment solutions on microbial inactivation, iron was added to reduce ORP readings and neutralizing buffer was added to neutralize chlorine. Inactivation of E. coli O157:H7 occurred within 30 s after application of JAW EO water with 10 mg/l residual chlorine and chemically modified solutions containing 13 mg/l residual chlorine. Inactivation of Gram-positive and -negative microorganisms occurred within 10 s after application of ROX EO water with 56 mg/l residual chlorine and chemically modified solutions containing 60 mg/l residual chlorine. B. cereus was more resistant to the treatments than E. coli O157:H7 and L. monocytogenes and only 3 log10 reductions were achieved after 10 s of ROX EO water treatment. B. cereus spores were the most resistant pathogen. However, more than 3 log10 reductions were achieved with 120-s EO water treatment.
Electrolyzed anodic NaCl solutions [EW+], prepared by the electrolysis of 0.1% NaCl, have been shown to instantly inactivate most pathogens that cause food-borne disease. Elimination of food-borne pathogens does not necessarily guarantee food safety because enterotoxins produced by pathogens may remain active. We have tested whether EW+ can inactivate Staphylococcal enterotoxin A (SEA), one of the major enterotoxins responsible for food poisoning. Fixed quantities of SEA were mixed with increasing molar ratios of EW+, and SEA was evaluated by reversed-phase passive latex agglutination (RPLA) test, immunoassay, native polyacrylamide gel electrophoresis (PAGE), and amino acid analysis after 30 min incubations. Exposure of 70 ng, or 2.6 pmol, of SEA in 25 microL of PBS to a 10-fold volume of EW+, or ca. 64.6 x 10(3)-fold molar excess of HOCl in EW+, caused a loss of immuno-reactivity between SEA and a specific anti-SEA antibody. Native PAGE indicated that EW+ caused fragmentation of SEA, and amino acid analysis indicated a loss in amino acid content, in particular Met, Tyr, Ile, Asn, and Asp. Staphylococcal enterotoxin-A excreted into culture broth was also inactivated by exposure to an excess molar ratio of EW+. Thus, EW+ may be a useful management tool to ensure food hygiene by food processing industries.
Electrolyzed oxidizing (EO) water has proved to be effective against foodborne pathogens attached to cutting boards and poultry surfaces and against spoilage organisms on vegetables; however, its levels of effectiveness against Listeria monocytogenes and Salmonella Typhimurium in cell suspensions have not been compared with those of other treatments. In this study, the oxidation reduction potentials (ORPs), chlorine concentrations, and pHs of acidic and basic EO water were monitored for 3 days at 4 and 25 degrees C after generation. There were no differences between the pHs or ORPs of acidic and basic EO waters stored at 4 or 25 degrees C. However, the free chlorine concentration in acidic EO water stored at 4 degrees C increased after 24 h. In contrast, the free chlorine concentration in acidic EO water stored at 25 degrees C decreased after one day. Cell suspensions of Salmonella Typhimurium and L. monocytogenes were treated with distilled water, chlorinated water (20 ppm), acidified chlorinated water (20 ppm, 4.5 pH), acidic EO water (EOA), basic EO water (EOB), or acidic EO water that was "aged" at 4 degrees C for 24 h (AEOA) for up to 15 min at either 4 or 25 degrees C. The largest reductions observed were those following treatments carried out at 25 degrees C. EOA and AEOA treatments at both temperatures significantly reduced Salmonella Typhimurium populations by > 8 log10 CFU/ml. EOA and AEOA treatments effectively reduced L. monocytogenes populations by > 8 log10 CFU/ml at 25degrees C. These results demonstrate the stability of EO water under different conditions and that EO water effectively reduced Salmonella Typhimurium and L. monocytogenes populations in cell suspensions.
To determine the efficacy of neutral electrolyzed water (NEW) in killing Escherichia coli O157:H7, Salmonella enteritidis and Listeria monocytogenes, as well as nonpathogenic E. coli, on the surface of tomatoes, and to evaluate the effect of rinsing with NEW on the organoleptic characteristics of the tomatoes.
The bactericidal activity of NEW, containing 444 or 89 mg l(-1) of active chlorine, was evaluated over pure cultures (8.5 log CFU ml(-1)) of the above-mentioned strains. All of them were reduced by more than 6 log CFU ml(-1) within 5 min of exposure to NEW. Fresh tomatoes were surface-inoculated with the same strains, and rinsed in NEW (89 mg l(-1) of active chlorine) or in deionized sterile water (control), for 30 or 60 s. In the NEW treatments, independent of the strain and of the treatment time, an initial surface population of about 5 log CFU sq.cm(-1) was reduced to <1 log CFU sq.cm(-1), and no cells were detected in the washing solution by plating procedure. A sensory evaluation was conducted to ascertain possible alterations in organoleptic qualities, yielding no significant differences with regard to untreated tomatoes.
Rinsing in NEW reveals as an effective method to control the presence of E. coli O157:H7, S. enteritidis and L. monocytogenes on the surface of fresh tomatoes, without affecting their organoleptic characteristics. This indicates its potential application for the decontamination of fresh produce surfaces.
The effects of chlorine and pH on the bactericidal activity of electrolyzed (EO) water were examined against Escherichia coli O157:H7 and Listeria monocytogenes. The residual chlorine concentration of EO water ranged from 0.1 to 5.0 mg/l, and the pH effect was examined at pH 3.0, 5.0, and 7.0. The bactericidal activity of EO water increased with residual chlorine concentration for both pathogens, and complete inactivation was achieved at residual chlorine levels equal to or higher than 1.0 mg/l. The results showed that both pathogens are very sensitive to chlorine, and residual chlorine level of EO water should be maintained at 1.0 mg/l or higher for practical applications. For each residual chlorine level, bactericidal activity of EO water increased with decreasing pH for both pathogens. However, with sufficient residual chlorine (greater than 2 mg/l), EO water can be applied in a pH range between 2.6 (original pH of EO water) and 7.0 while still achieving complete inactivation of E. coli O157:H7 and L. monocytogenes.
To ascertain the efficacy of neutral electrolysed water (NEW) in reducing Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Listeria monocytogenes on glass and stainless steel surfaces. Its effectiveness for that purpose is compared with that of a sodium hypochlorite (NaClO) solution with similar pH, oxidation-reduction potential (ORP) and active chlorine content.
First, the bactericidal activity of NEW was evaluated over pure cultures (8.5 log CFU ml-1) of the abovementioned strains: all of them were reduced by more than 7 log CFU ml-1 within 5 min of exposure either to NEW (63 mg l-1 active chlorine) or to NaClO solution (62 mg l-1 active chlorine). Then, stainless steel and glass surfaces were inoculated with the same strains and rinsed for 1 min in either NEW, NaClO solution or deionized water (control). In the first two cases, the populations of all the strains decreased by more than 6 log CFU 50 cm-2. No significant difference (P<or=0.05) was found between the final populations of each strain with regard to the treatment solutions (NEW or NaClO solution) or to the type of surface.
NEW was revealed to be as effective as NaClO at significantly reducing the presence of pathogenic and spoilage bacteria (in this study, E. coli, L. monocytogenes, P. aeruginosa and S. aureus) on stainless steel and glass surfaces.
NEW has the advantage of being safer than NaClO and easier to handle. Hence, it represents an advantageous alternative for the disinfection of surfaces in the food industry.
Minimally processed vegetables (MPV) have a short shelf-life. Neutral electrolysed oxidising water (NEW) is a novel decontamination method. The objective of this study was to test the potential of NEW to extend the shelf-life of a MPV, namely shredded cabbage. Samples of shredded cabbage were immersed in NEW containing 40 mg/L of free chlorine or tap water (control) up to 5 min, and then stored under equilibrium modified atmosphere at 4 degrees C and 7 degrees C. Proliferation of aerobic mesophilic bacteria, psychrotrophic bacteria, lactic acid bacteria and yeasts were studied during the shelf-life. Also pH and sensorial quality of the samples as well as O(2) and CO(2) composition of the headspace of the bags was evaluated. From the microbial groups, only psychrotrophic counts decreased significantly (P<0.05) due to the effect of NEW, but the counts in treated samples and controls were similar after 3 days of storage at 4 degrees C and 7 degrees C. Packaging configurations kept O(2) concentration around 5% and prevented CO(2) accumulation. pH increased from 6.1-6.2 to 6.4 during the shelf-life. No microbial parameter reached unacceptable counts after 14 days at 4 degrees C and 8 days of storage at 7 degrees C. The shelf-life of controls stored at 4 degrees C was limited to 9 days by overall visual quality (OVQ), while samples treated with NEW remained acceptable during the 14 days of the experiment. The shelf-life of controls stored at 7 degrees C was limited to 6 days by OVQ and browning, while that of samples treated with NEW were limited to 9 days by OVQ, browning and dryness. According to these results, a shelf-life extension of at least 5 days and 3 days in samples stored respectively at 4 degrees C and 7 degrees C can be achieved by treating shredded cabbage with NEW. NEW seems to be a promising method to prolong the shelf-life of MPV.
Food safety issues and increases in food borne illnesses have promulgated the development of new sanitation methods to eliminate pathogenic organisms on foods and surfaces in food service areas. Electrolyzed oxidizing water (EO water) shows promise as an environmentally friendly broad spectrum microbial decontamination agent. EO water is generated by the passage of a dilute salt solution ( approximately 1% NaCl) through an electrochemical cell. This electrolytic process converts chloride ions and water molecules into chlorine oxidants (Cl(2), HOCl/ClO(-)). At a near-neutral pH (pH 6.3-6.5), the predominant chemical species is the highly biocidal hypochlorous acid species (HOCl) with the oxidation reduction potential (ORP) of the solution ranging from 800 to 900mV. The biocidal activity of near-neutral EO water was evaluated at 25 degrees C using pure cultures of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Treatment of these organisms, in pure culture, with EO water at concentrations of 20, 50, 100, and 120ppm total residual chlorine (TRC) and 10min of contact time resulted in 100% inactivation of all five organisms (reduction of 6.1-6.7log(10)CFU/mL). Spray treatment of surfaces in food service areas with EO water containing 278-310ppm TRC (pH 6.38) resulted in a 79-100% reduction of microbial growth. Dip (10min) treatment of spinach at 100 and 120ppm TRC resulted in a 4.0-5.0log(10)CFU/mL reduction of bacterial counts for all organisms tested. Dipping (10min) of lettuce at 100 and 120ppm TRC reduced bacterial counts of E. coli by 0.24-0.25log(10)CFU/mL and reduced all other organisms by 2.43-3.81log(10)CFU/mL.
Consumption of minimally-processed, or fresh-cut, fruit and vegetables has rapidly increased in recent years, but there have also been several reported outbreaks associated with the consumption of these products. Sodium hypochlorite is currently the most widespread disinfectant used by fresh-cut industries. Neutral electrolyzed water (NEW) is a novel disinfection system that could represent an alternative to sodium hypochlorite. The aim of the study was to determine whether NEW could replace sodium hypochlorite in the fresh-cut produce industry. The effects of NEW, applied in different concentrations, at different treatment temperatures and for different times, in the reduction of the foodborne pathogens Salmonella, Listeria monocytogenes and Escherichia coli O157:H7 and against the spoilage bacterium Erwinia carotovora were tested in lettuce. Lettuce was artificially inoculated by dipping it in a suspension of the studied pathogens at 10(8), 10(7) or 10(5) cfu ml(-1), depending on the assay. The NEW treatment was always compared with washing with deionized water and with a standard hypochlorite treatment. The effect of inoculum size was also studied. Finally, the effect of NEW on the indigenous microbiota of different packaged fresh-cut products was also determined. The bactericidal activity of diluted NEW (containing approximately 50 ppm of free chlorine, pH 8.60) against E. coli O157:H7, Salmonella, L. innocua and E. carotovora on lettuce was similar to that of chlorinated water (120 ppm of free chlorine) with reductions of 1-2 log units. There were generally no significant differences when treating lettuce with NEW for 1 and 3 min. Neither inoculation dose (10(7) or 10(5) cfu ml(-1)) influenced the bacterial reduction achieved. Treating fresh-cut lettuce, carrot, endive, corn salad and 'Four seasons' salad with NEW 1:5 (containing about 50 ppm of free chlorine) was equally effective as applying chlorinated water at 120 ppm. Microbial reduction depended on the vegetable tested: NEW and sodium hypochlorite treatments were more effective on carrot and endive than on iceberg lettuce, 'Four seasons' salad and corn salad. The reductions of indigenous microbiota were smaller than those obtained with the artificially inoculated bacteria tested (0.5-1.2 log reduction). NEW seems to be a promising disinfection method as it would allow to reduce the amount of free chlorine used for the disinfection of fresh-cut produce by the food industry, as the same microbial reduction as sodium hypochlorite is obtained. This would constitute a safer, 'in situ', and easier to handle way of ensuring food safety.
c *Surviving population (log 10 CFU/ml) values are the means ± standard deviation with n = 10 for S. aureus, E. coli and Salmonella spp
- Zacharia Et Al
Un-treated
60 s
120 s
180 s
60 s
120 s
180 s
S. aureus
9.3 ± 0.03
3.95 ± 0.03
3.34 ± 0.04
2.92 ± 0.05
5.33 ± 0.03 a
5.94 ± 0.03 b
6.36 ± 0.05 c
E. coli
9.4 ± 0.03
3.79 ± 0.04
3.13 ± 0.06
2.71 ± 0.13
5.61 ± 0.06 a
6.27 ± 0.08 b
6.69 ± 0.14 c
Salmonella spp.
9.4 ± 0.01
3.81 ± 0.12
3.24 ± 0.11
2.61 ± 0.17
5.60 ± 0.13 a
6.17 ± 0.11 b
6.80 ± 017 c
*Surviving population (log 10 CFU/ml) values are the means ± standard deviation with n = 10 for S. aureus, E. coli and Salmonella spp. ▴ Microbial reduction (log 10 CFU/ml) values are
the means ± standard deviation with n = 10 for S. aureus, E. coli and Salmonella spp. Mean microbial reduction (log 10 CFU/ml reduction) with the different lower case letters on the
same row were significantly different at p b 0.05.
ISSA-ZACHARIA ET AL.