Development of a Predictive Model for Vibrio parahaemolyticus in Raw White Shrimps

Introduction: Vibrio parahaemolyticus is a halophilic bacterium that occurs naturally in estuarine environments and transmitted to humans primarily through the consumption of contaminated raw or undercooked seafood. This pathogen is a major causative agent of foodborne infection in Taiwan. However, information is limited about the growth and survival of naturally-occurring V. parahaemolyticus in raw shrimps under commercially relevant storage conditions in Taiwan.

Purpose: This study aimed to develop a mathematical model to describe the effect of storage temperature on the growth rate of naturally-occurring V. parahaemolyticus in raw white shrimps harvested in Taiwan.

Methods: Raw shrimps were placed in sterile containers and stored at 5, 10, 15, 20, 25, 30, and 35°C. At each sampling time, shrimps were analyzed for V. parahaemolyticus counts by a plate count method. The populations of V. parahaemolyticus in shrimps during storage were used to estimate the growth rates and correlated to the storage temperature to develop a mathematical model.

Results: The growth of V. parahaemolyticus in shrimps at 5 and 10°C were not observed. The average growth rates of V. parahaemolyticus at 15, 20, 25, 30, and 35°C were 0.021, 0.054, 0.101, 0.297, and 0.60 log CFU/h, respectively. In general, the observed growth rates were higher (P < 0.05) than the predicted rates from post-harvest shrimps described in the literature. A square-root model was developed for the growth rates of V. parahaemolyticus in shrimps as a function of storage temperature.

Significance: The findings may assist the seafood industry and risk managers in designing more effective temperature control systems for seafood production and distribution to reduce the risk associated with V. parahaemolyticus.