Reduction of bacteria on spinach, lettuce, and surfaces in food service areas using neutral electrolyzed oxidizing water

• Published in: Food microbiology 2008-02, Vol.25 (1), p.36-41
• Main Authors: Guentzel, Jane L., Liang Lam, Kang, Callan, Michael A., Emmons, Stuart A., Dunham, Valgene L.
• Format: Article
• Language: English
• Subjects: Animals; antimicrobial agents; Biological and medical sciences; Chlorides - pharmacology; Colony Count, Microbial; Consumer Product Safety; decontamination; Dose-Response Relationship, Drug; E. coli; Electrolysis; electrolytes; Electrolyzed oxidizing water; Enterococcus faecalis; Enterococcus faecalis - drug effects; Enterococcus faecalis - growth & development; Equipment Contamination - prevention & control; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - growth & development; food contact surfaces; Food Contamination - analysis; Food Contamination - prevention & control; Food industries; Food microbiology; food processing; food safety; food sanitation; food service; Food Services - standards; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Lactuca - microbiology; lettuce; Listeria monocytogenes; Listeria monocytogenes - drug effects; Listeria monocytogenes - growth & development; microbial growth; oxidants; Oxidation-Reduction; postharvest technology; protective effect; raw vegetables; salad bars; Salmonella typhimurium; Salmonella typhimurium - drug effects; Salmonella typhimurium - growth & development; Sanitation - methods; sanitizing; spinach; Spinacia oleracea; Spinacia oleracea - microbiology; Staphylococcus aureus; Staphylococcus aureus - drug effects; Staphylococcus aureus - growth & development; Treatment Outcome; Water - chemistry
• ISSN: 0740-0020; 1095-9998
• DOI: 10.1016/j.fm.2007.08.003

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 (∼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 900 mV. The biocidal activity of near-neutral EO water was evaluated at 25 °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 120 ppm total residual chlorine (TRC) and 10 min of contact time resulted in 100% inactivation of all five organisms (reduction of 6.1–6.7 log 10 CFU/mL). Spray treatment of surfaces in food service areas with EO water containing 278–310 ppm TRC (pH 6.38) resulted in a 79–100% reduction of microbial growth. Dip (10 min) treatment of spinach at 100 and 120 ppm TRC resulted in a 4.0–5.0 log 10 CFU/mL reduction of bacterial counts for all organisms tested. Dipping (10 min) of lettuce at 100 and 120 ppm TRC reduced bacterial counts of E. coli by 0.24–0.25 log 10 CFU/mL and reduced all other organisms by 2.43–3.81 log 10 CFU/mL.