Postharvest management of gray mold and brown rot on surfaces of peaches and grapes using electrolyzed oxidizing water.

This study evaluated the potential use of near-neutral (pH=6.3-6.5) electrolyzed oxidizing water (EO water) to inactivate pure cultures of Botrytis cinerea and Monilinia fructicola and to mitigate fungal infection of these organisms on fruit surfaces. Treatment of these organisms, in pure culture, with EO water at concentrations of 25, 50, 75, and 100ppm total residual chlorine (TRC) and 10 min of contact time resulted in a 6 log(10) spores/mL reduction of both organisms. A dip treatment or a dip and daily spray treatment of EO water were used to evaluate its ability to prevent or delay the onset of surface infection on fruit during postharvest packaging and in retail shelf environments. A 10 minute dip treatment of surface inoculated peaches (M. fructicola) in EO water prevented infection for 3 days and resulted in a 12.5% incidence of infection and a disease severity rating of 6% after 5 days of storage at 25 degrees C. Dipping of green table grapes inoculated with B. cinerea into EO water prevented infection for 7 days and resulted in a 1% incidence of infection and a disease severity rating of 2% after 10 days of storage at 25 degrees C. A dip and daily spray of peaches with EO water prevented infection for 12 days and resulted in a 10% incidence of infection and a 6% disease severity after 14 days of storage at 25 degrees C. A dip and daily spray of grapes with EO water prevented infection for 24 days and resulted in a 2% incidence of infection and a disease severity rating of 2% after 26 days of storage at 25 degrees C. The results from this study suggest that these solutions may prove to be effective for postharvest sanitation of fruit surfaces prior to packaging and may increase the shelf life of the fruit in commercial settings.

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

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.