Ren Tingting, Su Yi-Cheng
OSU Seafood Laboratory, Oregon State University, 2001 Marine Drive, Room 253, Astoria, Oregon 97103, USA.
J Food Prot. 2006 Aug;69(8):1829-34. doi: 10.4315/0362-028x-69.8.1829.
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.
牡蛎中副溶血性弧菌和创伤弧菌的污染是食品安全问题。本研究调查了电解氧化（EO）水处理对减少实验室污染牡蛎中副溶血性弧菌和创伤弧菌的效果。EO水在纯培养物中对副溶血性弧菌和创伤弧菌表现出很强的抗菌活性。在含0.5%氯化钠的EO水中，副溶血性弧菌（8.74×10⁷CFU/ml）和创伤弧菌（8.69×10⁷CFU/ml）的数量在15秒内迅速降至无法检测的水平（>6.6个对数级减少）。将刚收获的太平洋牡蛎接种副溶血性弧菌或创伤弧菌的五菌株混合菌液，浓度为10⁴和10⁶最可能数（MPN）/克，并在室温下用含1%氯化钠的EO水（氯，30 ppm；pH 2.82；氧化还原电位，1131 mV）处理。在处理0（处理前）、2、4、6和8小时时测定牡蛎中副溶血性弧菌和创伤弧菌的减少情况。将接种副溶血性弧菌或创伤弧菌的牡蛎在含1%氯化钠的EO水中放置4至6小时，副溶血性弧菌和创伤弧菌分别显著（P<0.05）减少1.13和1.05个对数MPN/克。发现牡蛎在含高浓度氯（>30 ppm）的EO水中长时间暴露（>12小时）对牡蛎有害。EO水可作为收获后处理方法以减少牡蛎中的弧菌污染。然而，处理时间应限制在4至6小时以避免牡蛎死亡。需要进一步研究以确定EO水处理对牡蛎感官特性的影响。
