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Enhancing the Quality and Safety of Foods by Electrolyzed (EO) Water


The overall objective of the proposed study is to demonstrate the advantage of EO water for enhancing the safety and quality of food related applications. Specific opjectives are: <OL> <LI> Evaluate and improve the stability in chemical composition of acidic EO water immediately after preparation and during storage <LI> Evaluate the efficacy of EO water for improving safety and retaining quality of fresh produce (both whole and minimally processed) <LI> Evaluate the effectiveness of EO water for sanitization and removing fecal materials during poultry processing <LI> Quantify and compare the amount of chlorine residue on food after EO water treatment <LI> Evaluate the corrosive effects of EO water on different food processing equipment surfaces <LI> Evaluate different EO water delivery technology on the effectiveness of EO water treatment <LI> Compare the wastewater quality and its environmental impact on acidic EO water and acidic EO water neutralized with alkaline EO water before discharge <LI> Evaluate the effect of acidic and alkaline EO water on the functional properties and quality of foods.

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NON-TECHNICAL SUMMARY: Electrolyzed (EO) water is produced on site by an EO water generator. It can destroy most of the food borne pathogens without affecting the quality of treated products.


APPROACH: Electrolyzed (EO) water produced from two different generators will be used for this study. The pH and ORP of the solutions will be measured using pH and ORP electrodes. The total free chlorine will be determined by an iodometry method using a digital titrator. Several processes will be investigated to evaluate their effect on the stability of EO water and a new EO water generator will be constructed to improve the stability of EO water. Safety and quality of whole and shredded lettuce leaves, strawberry, broccoli, tomato, and carrots after EO water treatment will be evaluated. Acidic EO water will be used to spray the poultry carcasses to reduce C. jejuni contamination and alkaline EO water will be used to remove fecal materials from poultry carcasses. The amount of residual chlorine in and on the treated sample and treatment solution after treatment will be quantified. Corrosive effect of EO water on different food processing equipment materials will be evaluated according to an ASTM procedure. To evaluate the potential of EO water for food preparation, the effect of EO water on noodle and bread making properties and the quality of rice, needle, and bread after cooking/baking will be evaluated.

PROGRESS: 2003/01 TO 2007/12<BR>
Electrolyzed oxidizing (EO) water is produced through electrolysis of a dilute salt solution resulting in a strong acidic EO water that has a high efficacy to inactive foodborne pathogens due to its high oxidation-reduction potential (ORP) and in combination with hypochlorous acid. Studies have been conducted to demonstrate that EO water is effective in reducing or eliminating foodborne pathogens on kitchen cutting boards, lettuce, poultry, alfalfa sprouts, shell eggs and seafood. EO water has also been demonstrated can be used to inactivate biofilms for preventing cross-contamination in a processing environment without corrosive effect on the treated surfaces. Major advantages of using EO water as an anti-microbial agent include: (1) EO water treatment is at least as effective as the chlorinated water treatment, (2) there is no need for handling potentially dangerous concentrated chemicals, (3) EO water generator is easy to operate and relatively inexpensive, (4) the process is environmentally friendly because production of EO water uses only water and sodium chloride, and (5) the properties of EO water can be controlled at the site of production. Fresh lettuce, tomatoes and shredded red cabbage are common ingredients used in making salads and coleslaw in restaurants. Contamination of fresh produce with pathogenic bacteria is a significant concern for restaurants. Produce are sometimes washed with water, which may or may not contain chlorine, at the restaurant and/or before being shipped to restaurants. However, these mild washing steps have been shown to be ineffective at completely removing pathogenic microorganisms from produce. EO water treatments similar to those that may exist in salad preparation areas in food service kitchens were conducted. Whole lettuce and cabbage leaves were spot inoculated with a mixture of five E. coli O157:H7 strains (8 log CFU/leaf), dried at 21C for 2 h, and held at 4C for 20 - 22 h. Running acidic EO water and immersion EO treatment treatments were conducted to evaluate their efficacy to remove and inactivate E. coli O157:H7. Treatment solutions after use were also evaluated for potential source of cross contamination. Washing lettuce and cabbage with running EO water reduced populations of the pathogen up to 1.8 and 2.5 log CFU/leaf, respectively. Combining washing with immersion treatment achieved at least additional 0.5 to 1 log reduction. Results indicate that application of EO water using a process mimicking a restaurant or food service operation can reduce the risk of E. coli O157:H7 on lettuce and cabbage at the time of consumption.

IMPACT: 2003/01 TO 2007/12<BR>

EO water has received a lot of attention from food processors and food service providers to help ensure food safety. On going research has demonstrated EO water can be easily adapted by food processing and food service industries to wash produce and hence provide additional safety measure.

PROGRESS: 2006/01/01 TO 2006/12/31<BR>

The ability of electrolyzed (EO) water to inactivate Listeria monocytogenes in suspension and biofilms on stainless steel in the presence of organic matter (sterile filtered chicken serum) was investigated. A five strain mixture of L. monocytogenes was treated with deionized, alkaline and acidic EO water containing chicken serum (0, 5, 10 ml/L) for 1 and 5 min. Coupons containing L. monocytogenes biofilms were also overlaid with chicken serum (0, 2.5, 5.0, 7.5 ml/L) and then treated with deionized water, alkaline and acidic EO water, alkaline followed by acidic EO water and a sodium hypochlorite solution for 30 and 60 s. Chicken serum decreased the ORP and chlorine concentration of acidic EO water but did not significantly affect its pH. In the absence of serum, acidic EO water containing 44 mg/L chlorine produced > 6-log reduction in L. monocytogenes in suspension but its bactericidal activity decreased with increasing serum concentration. Acidic EO water and acidified sodium hypochlorite solution inactivated L. monocytogenes biofilms to similar levels, and their bactericidal effect decreased with increasing serum concentration and increased with increasing time of exposure. The sequential 30-s treatment of alkaline EO water followed by acidic EO water produced 4- to 5-log reductions in L. monocytogenes biofilms, even in the presence of organic matter. EO water has alsi been used to reduce microbial population on seafood and platform of fish retailer. Tilapia were inoculated with E. coli and Vibro parahaemolyticus and then soaked in EO water for up to 10 min. EO water achieved additional 0.7 log CFU/cm2 reduction than tap water on E. coli after 1 min treatment and additional treatment time did not achieved additional reduction. EO water treatment also reduced V. parahaemolyticus by 1.5 log CFU/ cm2 after 5 min treatment and achieved 2.6 log CFU/ cm2 reduction after 10 min. The pathogenic bacteria were not detected in EO water after soaking treatment. In addition, EO water could effectively disinfect the platform of fish retailer in traditional and fish markets.

IMPACT: 2006/01/01 TO 2006/12/31<BR>

Research findings from this project have demonstrated that EO water can replace chemical pesticides to control plant diseases. The company which licensed the UGA EO water technology has sub-licensed the technology in South and Central America to a major international fresh flower company. In addition, one of the major poultry processors in Arkansas has conducted test trials in 2006 using acidic EO water as the treatment solution for poultry processing to kill foodborne pathogens. The company licensed the EO water technology from UGA is also in discussion with several poultry processors to provide this technology to reduce microbial risk of poultry.

PROGRESS: 2005/01/01 TO 2005/12/31<BR>

Biofilms were grown on 2 x 5 cm rectangular stainless steel coupons, in a 1:10 dilution of TSB containing a five strain mixture of L. monocytogenes for 48 hours at 25 C. The coupons with biofilms were then treated with acidic EO water or alkaline EO water, or with alkaline EO water followed by acidic electrolyzed (EO) water. Alkaline EO water alone did not produce significant reductions in L. monocytogenes biofilms. Treatment with acidic EO water only for 30 to120 s reduced the viable bacterial populations in the biofilms by 4.3 to 5.2 log CFU/coupon while the combined treatment of alkaline EO water followed by acidic EO water produced an additional 0.3 to 1.2 log CFU/coupon reduction. The population of L. monocytogenes reduced by treatments with acidic EO water, increased significantly with increasing time of exposure. Results suggest that alkaline and acidic EO water can be utilized together to achieve a better inactivation of biofilms than when applied individually. The efficacy of EO water for inactivating Salmonella Enteritidis and Listeria monocytogenes on shell eggs was evaluated. An increasing reduction in Listeria population was observed with increasing chlorine concentration from 16 to 77 mg/L and treatment time from 1 to 5 min, resulting in a maximal reduction of 3.70 log CFU/shell egg compared to a deionized water wash for 5 min. There was no significant difference in antibacterial activities against Salmonella and Listeria at the same treatment time between 45 mg/L of chlorinated water and 14-A acidic EO water treatment (p > 0.05). Reductions (log CFU/shell egg) of Listeria (4.39) and Salmonella (3.66) by 1 min alkaline EO water treatment followed by another 1 min of 14-A acidic EO water (41 mg/L chlorine) treatment had similar reduction as the 1 min 200 mg/L chlorinated water treatment for Listeria (4.01) and Salmonella (3.81). This study demonstrated that a combination of alkaline and acidic EO water wash is equivalent to 200 mg/L of chlorinated water wash for reducing populations of S. Enteritidis and L. monocytogenes on shell eggs. New York dressed chicken carcasses spot-inoculated with either ceca or C. jejuni were subjected to either spraying treatment with alkaline EO and 10% trisodium phosphate (TSP) water or combinations of spraying and immersion treatments with acidic EO and chlorinated water, respectively. Pre-spraying chicken carcass with alkaline EO water significantly lowered score (3.77) of ceca attachment than both tap water (4.07) and 10% TSP (4.08) treatment for the dorsal area. Combinations of pre- and post-spraying were significantly more effective than post-spraying only especially with alkaline EO water in removing fecal materials on the surface of chicken carcass. Although immersion only treatment with EO and chlorinated water significantly reduced the initial population (4.92 log CFU/g) of C. jejuni by 2.33 and 2.05 log CFU/g, respectively, combinations of spraying and immersion treatment did not improve bactericidal effect of sanitizers. Results indicated that alkaline EO water may provide an alternative to TSP in preventing attachment and removing of feces on the surface of chicken carcass.

IMPACT: 2005/01/01 TO 2005/12/31<BR>

EO water is a non-thermal process to inactivate foodborne pathogens. Research findings from this project have demonstrated EO water is an effective tool to help ensure the food safety and security in the U.S. The EO water technology has recently been evaluated by several major poultry processors and results were much better than their current methods to eliminate foodborne pathogens.
PROGRESS: 2004/01/01 TO 2004/12/31<BR>

Acidic electrolyzed (EO) water is very effective for inactivation of different foodborne pathogens. The effects of production parameters (voltage, NaCl concentration, flow rate, and temperature) on the properties of EO water have been evaluated. For pH and oxidation-reduction potential (ORP), NaCl concentration was the most significant factor followed by voltage, electrolyte flow rate and temperature, respectively. However, in the case of residual chlorine, flow rate was relatively more important than voltage. Response surface methodology yielded models to predict EO water properties as functions of the process parameters studied, with very high coefficients of determination (R2=0.872 to 0.938). In general, the higher the NaCl concentration and voltage, the higher the ORP and residual chlorine of EO water. The effects of chlorine and pH on the bactericidal activity of EO water were also examined against E. coli O157:H7 and L. 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.

IMPACT: 2004/01/01 TO 2004/12/31<BR>

EO water is a non-thermal process to inactivate foodborne pathogens. Research findings from this project have demonstrated EO water is an effective tool to help ensure the food safety and security in the U.S. University of Georgia Research Foundation has filled a U.S. patent application based on the research findings from our studies.

Frank, Joseph; Hung, Yen-Con
University of Georgia
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