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Electrolyzed water (EW) is known by its bactericidal efficacy and capability to oxidize organic matter. The present research evaluated the efficacy of recently developed electrolytic cells able to generate higher concentration of reactive oxygen species using lower power and salt concentration than conventional cells. This study tested the inactivation of Escherichia coli O157:H7, the organic matter depletion and trihalomethane (THM) generation by EW in process wash water under dynamic conditions. To achieve this, clean tap water was continuously added up to 60 min with artificial process water with high chemical oxygen demand (COD) inoculated with E. coli O157:H7, in experiments performed in a pilot plant that recirculated water through one electrolytic cell. Plate counts of E. coli O157:H7, COD, THMs, free, combined and total chlorine, pH, temperature and oxidation-reduction potential were determined. Results indicate that the novel electrolysis system combined with minimal addition of NaCl (0.05) was able to suppress E. coli O157:H7 population build-up and decreased the COD accumulation in the process wash water. THM levels in the water were relatively high but its concentration in the washed product was marginal. Highly effective electrolysis has been proven to reduce the occurrence of foodborne diseases associated with cross-contamination in produce washers without having an accumulation of THMs in the washed product.

The effects of low-concentration electrolysed water (LcEW) (4 mg/L free available chlorine) combined with mild heat on the safety and quality of fresh organic broccoli (Brassica oleracea) were evaluated. Treatment with LcEW combined with mild heat (50 C) achieved the highest reduction in naturally occurring microorganisms and pathogens, including inoculated Escherichia coli O157:H7 and Listeria monocytogenes (P < 0.05). In terms of the antioxidant content of the treated broccoli, the total phenolic levels and ferric reducing antioxidant power remained unchanged however, the oxygen radical absorbance capacity of the treated broccoli was higher than that of the untreated control. In addition, mild heat treatment resulted in an increase in firmness. The increased firmness was attributed to changes in the pectin structure, including the assembly and dynamics of pectin. The results revealed that mild heat induced an antiparallel orientation and spontaneous aggregation of the pectin chains. This study demonstrated that LcEW combined with mild heat treatment was effective to reduce microbial counts on fresh organic broccoli without compromising the product quality.

This study was designed to evaluate the efficacy of slightly acidic electrolyzed water (SAEW) to reduce natural microbiota on celery and cilantro at different available chlorine concentrations (ACC), different treatment time and temperatures. Additionally, SAEW treated celery and cilantro were stored at 4 and 20 C for 6 days and population of total aerobic bacteria and yeast and mold were also determined at day 0, 2, 4 and 6, separately. Results showed that log reduction of total aerobic bacteria and yeast and mold significantly increased with increasing ACC and treatment time, respectively (p < 0.05). Celery and cilantro treated with SAEW at 30 mg/L ACC for 5 min and 25 mg/L for 7 min reduced yeast and mold to non-detectable level. No significant difference was observed for disinfection efficacy of SAEW on celery and cilantro at different temperatures (4, 20 and 37 C) (p > 0.05). The microbial population on celery and cilantro maintained at a low level during storage at 4 and 20 C after SAEW treatment (total aerobic bacteria: 3.34.1 log CFU/g, yeast and mold: 2.23.5 log CFU/g). The microbial inactivation effect as well as the absence of any sensory alterations on treated celery and cilantro rendered SAEW a promising disinfectant, which can be applied in fresh produce wash to control natural microbiota.

Automated produce washers can be a useful processing aid when treating fresh produce contaminated with pathogens. The of near neutral pH electrolyzed (NEO) water as a wash or sanitizing solution has been shown to lead to significant reductions of Escherichia coli O157:H7 and Salmonella on fresh produce. To further enhance reported pathogen reductions, the effects of a combined NEO water (155 mg/L free chlorine, pH 6.5) and ultrasound wash protocol on lettuce and tomatoes inoculated with E. coli O157:H7 and S. Typhimurium DT 104 were studied. The effects of the pH of NEO water and washer agitation on pathogen reductions were also assessed. Inoculated tomatoes and lettuce leaves were treated with either chilled deionized water or NEO water, with or without 20 kHz ultrasound (130 W and 210 W). Tomatoes were treated for 1, 3 and 5 min while lettuce was treated for 5, 10 and 15 min. Ultrasound significantly increased the oxidation-reduction potential (ORP) of NEO water (p < 0.05) but did not affect the pH and free chlorine concentration (p > 0.05). Increased washing time and higher ultrasonic power led to significantly greater reductions of both pathogens on produce items (p < 0.05). NEO water combined with 210 W ultrasonication for 15 min led to 4.4 and 4.3 log reductions of E. coli O157:H7 and S. Typhimurium on lettuce, respectively, while 210 W ultrasound for 5 min completely inactivated both pathogens on tomatoes. Both pathogens were completely inactivated in NEO water solutions, suggesting that its presents little chance of cross-contamination.

This paper focused on the effectiveness of electrolyzed water (EW) at different concentrations (5, 25, 50 and 100 mg/L) combined with passive atmosphere packaging on the quality of mushroom. In order to understand the effect of EW on mushrooms, gas composition inside packages, weight loss, pH, whiteness and browning index, texture profile analysis (TPA), cap development, electrolyte leakage and FT-NIR analysis were performed during the twelve days of storage at 4 C. Samples washed with 25 and 50 mg/L EW consumed O2 lower than the other treatments. Mushrooms treated with 25 mg/L EW had a significantly lower electrolyte leakage values than untreated and 5 mg/L treated mushrooms. Mushrooms treated with 25 mg/L EW had the highest whiteness index and lowest browning index. EW treatments at the concentrations of 25 and 50 mg/L maintained the textural parameters and slowed down the weight loss better than other treatments. FT-NIR analysis supported the results obtained by weight loss and electrolyte leakage. In conclusion, the results of this research support the idea that combined of EW treatment and passive modified atmosphere packaging can be used to extend the shelf life of mushrooms

 

Journal of General Plant Pathology 82.4 (2016): 186-189

Neutral electrolyzed water (NEW: pH 6.57.5) 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.

Food and Bioproducts Processing 98 (2016): 333-340

Product decontamination is one of the most important processes of the hygienic practice in food industries such as Minimally Processed Vegetables (MPV) plants and sodium hypochlorite (NaOCl) solutions are commonly used as a biocide for disinfection. Although it may be corrosive and irritating when compared to , reducing the free chlorine concentration needed to sanitize salads, also decreasing water consumption whilst taking into account environmental and food quality impacts.

Food Control 67 (2016): 177-182

The objective of this study was to determine the efficacy of electrolyzed oxidizing (EO) water in reducing natural microbiota on radish seed and sprout during seed soaking and sprouting. EO water with different available chlorine concentrations (ACC, 15, 20, 28, 33 and 40 mg/L) and different pH (2.5, 3.5, 4.5, 5.5 and 6.5) were used to soak radish seeds for 12 h and the surviving population of total aerobic bacteria, yeast and mold, and germination rate were determined. On the other hand, EO water with ACC of 30 and 50 mg/L was applied to spray sprouts during seed sprouting and the antimicrobial efficacy of EO water, as well as length, gross weight and dry weight of sprout were evaluated. The results showed that the population of natural microbiota decreased with increasing ACC of EO water, while no significant difference was observed among EO waters with different pH levels that were applied while soaking the seeds. EO water with higher ACC and lower pH slightly reduced the germination percentage of radish seed during seed soaking. EO waters with ACC of 30 and 50 mg/L sprayed during seed sprouting resulted in 1.39 and 1.58 log reductions of total aerobic bacteria, yeast and mold, respectively, and improved the length, gross weight and dry weight of the sprouts. Therefore, EO water with low ACC and near neutral pH could be used to soak seeds and water sprouts throughout seed germination and sprouting to control the population of natural microbiota on seeds and sprouts.

Slightly acid electrolyzed water (SAcEW) and ultrasound (US) treatment have emerged as an environmental-friendly antimicrobial agent. However, SAcEW treatment alone shows low antimicrobial efficiency. Therefore, the aim of this study was to develop a hurdle approach that combined SAcEW and US to improve the antimicrobial effect against Bacillus cereus as well as inhibition of the growth on potato. US treatment under different conditions of dip times, acoustic energy densities (AED) and temperatures were conducted to obtain the optimal condition. Our findings demonstrate that 3 min of US with 400 W/L of AED at 40 C treatment (US 40 C) significantly (p 0.05) reduced B. cereus population by 2.3 0.1 log CFU/g with minimal change in the color of potato. In addition, 3 min of SAcEW (pH, 5.35.5 ORP, 958981 mV ACC, 2830 mg/L) simultaneous with US40 C treatment (SAcEW US40 C) an approximately 3.0 log CFU/g reduction in B. cereus. Furthermore, SAcEW US40 C treatment efficiently extended lag time of B. cereus by 0.210.5 hrs, reduced that of specific growth rate by 0.010.23 log CFU/h during storage at different temperatures from 5 to 35 C. Therefore, this combined hurdle technology is capable of improving microbial safety of potato during storage and distribution.

eafy vegetables are the major source of nitrite intake in the human diet, and technological processing to control nitrite levels in harvested vegetables is necessary. In the current work, the effect of electrolyzed oxidizing water (EOW) on the nitrite and nitrate levels in fresh spinach during storage was studied. EOW treatment, including slightly acidic electrolyzed water and acidic electrolyzed water, was found to effectively reduce nitrite levels in fresh spinach during storage levels in the late period were 30 to 40% lower than that of the control. However, the nitrate levels in fresh spinach during storage were not influenced by EOW treatment. The reduction of nitrite levels in EOW-treated fresh spinach during storage can be attributed to the inactivation of nitrate reductase directly and to the reduction of bacterial populations. Our results suggest that treatment with slightly acidic electrolyzed water may be a better choice to control nitrite levels in fresh vegetables during storage. This study provided a useful method to reduce nitrite levels in fresh spinach.

In the present study, the disinfection efficacy on fresh-cut cilantro of the combination of strongly acidic electrolyzed water (AcEW) and alkaline electrolyzed water (AlEW) was evaluated, in comparison with single slightly acidic electrolyzed water (SAEW) and single AcEW treatments. The populations of E. Coli O78 on inoculated cilantro treated by AlEW 5 min + AcEW 5 min, was not detected while 3.43 and 3.73 log10 CFU/g in the AlEW 2.5 min + AcEW 2.5 min and AcEW 2 min + AlEW 2 min + AcEW 2 min treatments respectively. Our results implied that the bactericidal abilities of the combination of AlEW and AcEW treatments were higher than that of single AcEW and SAEW, which also was demonstrated microscopically by scanning electron microscopy (SEM). Moreover, the efficacy of combination of AcEW and AlEW in reducing natural micro flora on fresh-cut cilantro was also evaluated compared with single AcEW and SAEW. The results showed that the combination of AlEW and AcEW had stronger sterilization ability than single AcEW and SAEW. Considering the utilizations of AlEW and disinfection efficacy, we suggest that the combination of AlEW and AcEW may also be a better choice in fresh-cut produce.

Water can be a vector for foodborne pathogen cross-contamination during washing of vegetables if an efficient method of water disinfection is not used. Chlorination is the disinfection method most widely used, but it generates disinfection by-products such as trihalomethanes (THMs). Therefore, alternative disinfection methods are sought. In this study, a dynamic system was used to simulate the commercial conditions of a washing tank. Organic matter and the inoculum of Escherichia coli O157:H7 were progressively added to the wash water in the washing tank. We evaluated the effectiveness of the electrolyzed water (EW) when combining with the addition of salt (1, 0.5 and 0.15 g/L NaCl) on the pathogenic inactivation, organic matter depletion and THM generation. Results indicated that electrolysis of vegetable wash water with addition of salt (0.5 g/L NaCl) was able to eliminate E. coli O157:H7 population build-up and decrease COD accumulation while low levels of THMs were produced.

This study evaluated the efficacy of individual treatments (thermosonication [TS+DW] and slightly acidic electrolyzed water [SAcEW]) and their combination on reducing Escherichia coli O157:H7, Listeria monocytogenes, and spoilage microorganisms (total bacterial counts [TBC], Enterobacteriaceae, Pseudomonas spp., and yeast and mold counts [YMC]) on fresh-cut kale. For comparison, the antimicrobial efficacies of sodium chlorite (SC; 100 mg/L) and sodium hypochlorite (SH; 100 mg/L) were also evaluated. Each 10 g sample of kale leaves was inoculated to contain approximately 6 log CFU/g of E. coli O157:H7 or L. monocytogenes. Each inoculated or uninoculated samples was then dip treated with deionized water (DW; control), TS+DW, and SAcEW at various treatment conditions (temperature, physicochemical properties, and time) to assess the efficacy of each individual treatment. The efficacy of TS+DW or SAcEW was enhanced at 40 C for 3 min, with an acoustic energy density of 400 W/L for TS+DW and available chlorine concentration of 5 mg/L for SAcEW. At 40 C for 3 min, combined treatment of thermosonication 400 W/L and SAcEW 5 mg/L (TS+SAcEW) was more effective in reducing microorganisms compared to the individual treatments (SAcEW, SC, SH, and TS+DW) and combined treatments (TS+SC and TS+SH), which significantly (P < 0.05) reduced E. coli O157:H7, L. monocytogenes, TBC, Enterobacteriaceae, Pseudomonas spp., and YMC by 3.32, 3.11, 3.97, 3.66, 3.62, and >3.24 log CFU/g, respectively. The results suggest that the combined treatment of TS+SAcEW has the potential as a decontamination process in fresh-cut industry.

This study investigated the effect of ultrasonic treatment on the physicochemical properties (pH, available chlorine concentration (ACC), oxidation reduction potential (ORP), spectrophotometric characteristics) of slightly acidic electrolyzed water (SAEW). The effects of individual treatments (ultrasound and SAEW) and their combination on microbial loads and quality of cherry tomatoes and strawberries were also studied. The results indicated that a 10 min ultrasonic treatment had no effect on pH, ACC, or ORP of SAEW. Ultrasound enhanced the bactericidal activity of SAEW which resulted in 1.77 and 1.29 log reductions on total aerobic bacteria, and 1.50 and 1.29 log reductions on yeasts and molds, respectively for cherry tomatoes and strawberries. The firmness of cherry tomatoes decreased while all other qualities considered were unaffected. This research indicates that SAEW in combination with ultrasound treatment has potential as a sanitization treatment to improve the efficacy of microbial inactivation on fresh produce without compromising product quality.

Three experiments were performed to enumerate the natural microflora on unwashed peaches, known as field peaches, and to determine the efficacy of using acidified electrolyzed water as a topical antimicrobial to remove or reduce the number of the natural microflora or inoculated Listeria innocua from to peach surfaces. During the first experiment, field peaches were divided into four treatment groups: no wash (NW), tap water wash (TW), acidified electrolyzed water wash (AEW), and chlorinated water wash (CL). Peaches were dipped into each of the treatment solutions at ambient temperature and immediately removed (approximately 5 seconds). Peaches were then rinsed in 100 mL of 0.1% peptone and rinsates were plated on aerobic plate count agar for enumeration. For the second experiment, exposure time to the treatment solutions and the temperature of the same treatment solutions were studied. Field peaches were again divided into NW, TW, AEW, and CL but treatments were applied using two exposure times of 5 seconds and 40 minutes at a temperature of 2C (samples were given either a 0 or 40 in their labels to denote exposure time in minutes where 5 second exposures = 0 minutes e.g. TW-0, TW-40, AEW-0, etc.). Rinsing and plating was conducted as mentioned above. Experiment three investigated the efficacy of NW, TW, AEW, and Cl, in reducing numbers of Listeria innocua on peaches that were previously inoculated and held at 4C for 24 hours. Inoculated peaches were dipped in treatment solutions for 5 second and 40 minute times at 2C. Results showed that exposure time had a significant effect on bacterial reduction for both AEW and Cl treatments. Average aerobic counts from all NW peaches was 4.2 log10 CFU/g peach for natural microflora and 4.3 log10 CFU/g peach for samples inoculated with iii Listeria. The following results show the number of bacteria recovered (log10 CFU/g peach) from natural microflora samples and Listeria inoculated samples, respectively: NW = 4.2 and 4.9, TW0 = 3.8 and 4.3, TW-40 = 3.2 and 4.7, AEW-0 = 3.6 and 3.7, AEW-40 = 2.6 and 1.6, CL=0 = 3.7 and 3.7, and CL-40 = 2.3 and 1.9. Greatest reductions were found with AEW-40 and CL-40 at refrigerated temperatures against both aerobic microorganisms and Listeria innocua. They reduced natural microflora counts by approximately 1.6 and 1.9 log10 CFU/g peach, respectively and they also reduced Listeria innocua counts by 3.3 and 3.0 log10 CFU/g peach, respectively. Listeria innocua, like monocytogenes, thrives in cold environments and the analysis of this studys results suggest that Listeria in TW-40 may have reattached to peaches during exposure. Color studies were also performed on the peaches from the preliminary experiment and Experiment 2 to determine the effects of exposing the peaches to low pH environment such as that of the AEW used in this study. Peaches were analyzed for Lab color data prior to their exposure to treatment solutions then they were analyzed again after their treatment concluded and they had air dried until no visible moisture remained. There was no significant color difference shown in any of the peaches when the pre- and post-treatment data was compared. Results from these studies demonstrate that total aerobic microorganisms and Listeria spp. may be reduced, but not eliminated, during washing (by dipping) with AEW or CL with similar reductions for both antimicrobial treatments.

The disinfection efficacy of acidic electrolyzed water (AEW) on the fresh-cut vegetables has been recognized. However, the application of AEW in the fresh-keeping of fresh-cut vegetables was limited due to its low pH (<2.7) and higher available chlorine concentration (80200mg/L). In the present study, the microbial reduction and storage qualities of fresh-cut cilantro treated by slightly acidic electrolyzed water (SAEW) were evaluated. The results demonstrated that AEW, mild heat AEW, SAEW and mild heat SAEW treatments could reduce the populations on fresh-cut cilantro at 0 day. However, there were no significant differences among all the treatments during the late storage periods. SAEW and mild heat SAEW treatments could keep the firmness of fresh-cut cilantro and maintain the level of electrolyte leakage in comparison with other treatments. SAEW treatment showed the advantage in keeping the overall quality of fresh-cut cilantro compared with other treatments. SAEW may be a better choice in the storage of fresh-cut cilantro than AEW.

The disinfection efficacy of acidic electrolyzed water (AEW) on the fresh-cut vegetables has been recognized. However, the application of AEW in the fresh-keeping of fresh-cut vegetables was limited due to its low pH (<2.7) and higher available chlorine concentration (80200mg/L). In the present study, the microbial reduction and storage qualities of fresh-cut cilantro treated by slightly acidic electrolyzed water (SAEW) were evaluated. The results demonstrated that AEW, mild heat AEW, SAEW and mild heat SAEW treatments could reduce the populations on fresh-cut cilantro at 0 day. However, there were no significant differences among all the treatments during the late storage periods. SAEW and mild heat SAEW treatments could keep the firmness of fresh-cut cilantro and maintain the level of electrolyte leakage in comparison with other treatments. SAEW treatment showed the advantage in keeping the overall quality of fresh-cut cilantro compared with other treatments. SAEW may be a better choice in the storage of fresh-cut cilantro than AEW.

The ability of acidic electrolyzed oxidizing water (AEO) and neutral electrolyzed oxidizing water (NEO) to inactivate the murine norovirus (MNV-1) surrogate for human norovirus and hepatitis A virus (HAV) in suspension and on stainless steel coupons in the presence of organic matter was investigated. Viruses containing tryptone (0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) were mixed with AEO and NEO for 1 min. In addition, stainless steel coupons containing MNV-1 with or without organic matter were treated with AEO or NEO for 3, 5, and 10 min. AEO was proven effective and generally killed more MNV-1 and HAV in suspension than NEO. Depending on the EO water generator, free chlorine concentrations are required to inactivate MNV-1 and HAV by 3-log PFU/mL or greater ranged from 30 mg/L to 40 mg/L after a 1 min contact time. The virucidal effect increased with increasing free chlorine concentration and decreased with increasing tryptone concentration in suspension. Both AEO and NEO at 70100 mg/L of free chlorine concentration significantly reduced MNV-1 on coupons in the absence of organic matter. However, there was no significant difference between these two treatments in the presence of organic matter. In addition, the efficacy of these two EO waters on stainless steel coupons increased with the increasing treatment time. Results indicated that AEO and NEO can reduce MNV-1 and HAV in suspension. However, higher free chlorine concentrations and longer treatment times may be necessary to reduce viruses on contact surfaces or in the presence of organic matter.

 

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