Temperature Effects on the Depuration of Vibrio parahaemolyticus and Vibrio vulnificus from the American Oyster ( Crassostrea virginica )

This study investigated temperature effects on depuration for reducing Vibrio parahaemolyticus and Vibrio vulnificus in American oyster (Crassostrea virginica). Raw oysters were inoculated with 5-strain cocktail of V. parahaemolyticus or V. vulnificus to levels of 10(4) to 10(5) MPN (most probable number)/g and depurated in artificial seawater (ASW) at 22, 15, 10, and 5 degrees C. Depuration of oysters at 22 degrees C had limited effects on reducing V. parahaemolyticus or V. vulnificus in the oysters. Populations of V. parahaemolyticus and V. vulnificus were reduced by 1.2 and 2.0 log MPN/g, respectively, after 48 h of depuration at 22 degrees C. Decreasing water temperature to 15 degrees C increased the efficacy of depuration in reducing V. parahaemolyticus and V. vulnificus in oysters. Reductions of V. parahaemolyticus and V. vulnificus in oysters increased to 2.1 and 2.9 log MPN/g, respectively, after 48 h of depuration at 15 degrees C. However, depurations at 10 and 5 degrees C were less effective than at 15 degrees C in reducing the Vibrio spp. in oysters. Extended depuration at 15 degrees C for 96 h increased reductions of V. parahaemolyticus and V. vulnificus in oysters to 2.6 and 3.3 log MPN/g, respectively.