Title: Refrigerated Seawater Depuration for Reducing Vibrio parahaemolyticus Contamination in Raw Pacific Oysters (Crassostrea gigas).

Vibrio parahaemolyticus is a seafood-borne pathogen that can cause gastroenteritis in humans. This study investigated the effectiveness of refrigerated seawater (5°C) depuration on reducing V. parahaemolyticus in raw Pacific oysters (Crassostrea gigas). Raw Pacific oysters were inoculated with a mixed culture of five clinical strains of V. parahaemolyticus and depurated with cold seawater (5°C) in a pilot scale recirculating system. The refrigerated seawater depuration was more efficient in reducing V. parahaemolyticus contamination in oysters harvested in winter than in summer. Populations of V. parahaemolyticus in oysters harvested in winter were reduced by>1.2 log MPN/g after 24 h of depuration in refrigerated seawater. Reductions of V. parahaemolyticus in the oysters increased to about 2.3 log MPN/g after 48 h and reached 3.1 log after 96 h of the process. However, it required 144 h of depuration in the refrigerated seawater to achieve a 3-log (MPN/g) reduction of V. parahaemolyticus in oysters harvested in summer. The efficacies of refrigerated seawater depuration in reducing V. parahaemolyticus were determined at a rate of 0.0211-log/h in oysters harvested in the summer and 0.0362-log/h in oysters harveste