Elimination of Vibrio parahaemolyticus Contamination in Shucked Oysters (Crassostrea plicatula) to with Natural Antimicrobial Agents TeaPolyphenols

In this study, the survival of Vibrio parahaemolyticus in suspension in the presence of tea-polyphenols for 6h was first examined. The shucked oysters containing V. parahaemolyticus then were exposed to 2048 mu g/mL, 1024 mu g/mL and 512 mu g/mL tea-polyphenols for 4h and the population of V. parahaemolyticus in shucked oysters was determined every 1h. In addition, shucked oysters containing V. parahaemolyticus exposed into the dose of 1024 mu g/mL tea-polyphenols were held at various temperature (0, 5, and 20 degrees C) to examine survival of V. parahaemolyticus every 6h till 24h. Populations of V. parahaemolyticus in oyster were determined using 3-tube most probable number (MPN) method. The study found that the MIC of tea-polyphenols to Vibrio parahaemolyticus suspension is 1024 mu g/mL; when exposed to 2048 mu g/mL, 1024 mu g/mL and 512 mu g/mL tea-polyphenols for 4h, the population of V. parahaemolyticus in shucked oysters decreased by 3.29,2.43 and 1.84 Log(10)MPN/g respectively; 0, 5 and 20 degrees C, 1024 mu g/mL tea-polyphenols can decrease the population of V. parahaemolyticus in shucked by 4.10, 3.32 and 3.00Log MPN/g at 24th h. Sensory analysis showed that treatments of tea-polyphenols at concentrations 1024 mu g/mL did not cause negative effects on taste of oyster meat. These results indicated that tea-polyphenols have bactericidal effects against V. parahaemolyticus and can be applied to shucked oysters to reduce contamination of V. parahaemolyticus.