Application of grape seed extract in depuration for decontaminating Vibrio parahaemolyticus in Pacific oysters (Crassostrea gigas)

- The application of grape seed extract (GSE) in oyster depuration was investigated.
- Depuration with GSE enhanced reductions of V. parahaemolyticus in oysters.
- The application of GSE in depuration did not cause mortality of the Pacific oysters.

This study investigated the potential application of grape seed extract (GSE) in depuration to increase its efficacy in reducing Vibrio parahaemolyticus populations in Pacific oysters (Crassostrea gigas). Pacific oysters were inoculated with five clinical strains of V. parahaemolyticus to 104−5 MPN/g and depurated in UV-irradiated artificial seawater (ASW) containing GSE at a level of 1.0% (1.8 mg/mL total phenolic contents as gallic acid equivalents) or 1.5% (3.1 mg/mL total phenolic contents as gallic acid equivalents) at 12.5 °C for up to 5 days. Changes of V. parahaemolyticus populations in oysters during depuration were analyzed every 24 h using the three-tube most probable number (MPN) method. The populations of V. parahaemolyticus in inoculated oysters decreased by 3.06 and 3.71 log MPN/g, respectively, after 4 and 5 days of depuration in ASW at 12.5 °C. However, populations of V. parahaemolyticus in oysters were reduced by 3.01 and 4.18 log MPN/g after 2 days of depuration at 12.5 °C in ASW containing 1.0 and 1.5% GSE, respectively. Further studies confirmed that depuration using ASW containing 1.5% GSE with 3.1 mg/mL total phenolic contents as gallic acid equivalents at 12.5 °C for two days was capable of achieving >3.52 log MPN/g reductions of V. parahaemolyticus in Pacific oysters.