Effects of electrolyzed oxidizing water treatment on reducing Vibrio parahaemolyticus and Vibrio vulnificus in raw oysters.
Contamination of Vibrio parahaemolyticus and Vibrio vulnificus in oysters is a food safety concern. This study investigated effects of electrolyzed oxidizing (EO) water treatment on reducing V. parahaemolyticus and V. vulnificus in laboratory-contaminated oysters. EO water exhibited strong antibacterial activity against V. parahaemolyticus and V. vulnificus in pure cultures. Populations of V. parahaemolyticus (8.74 x 10(7) CFU/ml) and V. vulnificus (8.69 x 10(7) CFU/ml) decreased quickly in EO water containing 0.5% NaCl to nondetectable levels (> 6.6 log reductions) within 15 s. Freshly harvested Pacific oysters were inoculated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus at levels of 10(4) and 10(6) most probable number (MPN)/g and treated with EO water (chlorine, 30 ppm; pH 2.82; oxidation-reduction potential, 1131 mV) containing 1% NaCl at room temperature. Reductions of V. parahaemolyticus and V. vulnificus in oysters were determined at 0 (before treatment), 2, 4, 6, and 8 h of treatment. Holding oysters inoculated with V. parahaemolyticus or V. vulnificus in the EO water containing 1% NaCl for 4 to 6 h resulted in significant (P < 0.05) reductions of V. parahaemolyticus and V. vulnificus by 1.13 and 1.05 log MPN/g, respectively. Extended exposure (> 12 h) of oysters in EO water containing high levels of chlorine (> 30 ppm) was found to be detrimental to oysters. EO water could be used as a postharvest treatment to reduce Vibrio contamination in oysters. However, treatment should be limited to 4 to 6 h to avoid death of oysters. Further studies are needed to determine effects of EO water treatment on sensory characteristics of oysters.
Ren
Tingting
T
OSU Seafood Laboratory, Oregon State University, 2001 Marine Drive, Room 253, Astoria, Oregon 97103, USA.
Su
Yi-Cheng
YC
D000818:Animals; D002713:Chlorine / Q000494:pharmacology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004203:Disinfection / Q000379:methods; D004572:Electrolysis; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D010125:Ostreidae / Q000382:microbiology*; D010084:Oxidation-Reduction; D012758:Shellfish / Q000382:microbiology* / Q000592:standards; D012965:Sodium Chloride / Q000494:pharmacology; D013649:Taste; D013696:Temperature; D013997:Time Factors; D014736:Vibrio parahaemolyticus / Q000187:drug effects / Q000254:growth & development*; D041261:Vibrio vulnificus / Q000187:drug effects / Q000254:growth & development*; D014867:Water / Q000494:pharmacology*
D014867:Water; D012965:Sodium Chloride; D002713:Chlorine