Effects of cold storage and thermal treatment on growth and survival of pathogenic Vibrio parahaemolyticus

This study investigated the effects of temperature on the survival of Vibrio parahaemolyticus during cold storage and heating process. V. parahaemolyticus enriched in sterile alkaline peptone water (APW) supplemented with 1.5% NaCl (APW-salt broth) at 37°C overnight (12-16h) was subjected to cold storage (-30, -18, 0, 5, 10, 15 and 20°C) and heating treatment (50, 55, 60, 70, 80, and 90°C) at various temperatures. Populations of V. parahaemolyticus were determined before and after the treatment. Results showed that showed V. parahaemolyticus in APW-salt broth increased rapidly when temperature was higher than 15°C, but decreased gradually at 0 and 5 °C. Freezing treatment could greatly decrease the populations of V. parahaemolyticus in APW-salt broth. Storage at -18°C was more effective in inactivating V. parahaemolyticus than that at -30°C. Keeping V. parahaemolyticus frozen at -18 and -30 °C for 15 to 30 days could reducing the pathogen to non-detectable levels (<;3 MPN/g). Heating at 60 °C for 5 min, at 70 °C for 2 min, or at 80°C or higher for 1 min also reduced V. parahaemolyticus from 10,000 MPN/g to non-detectable level. In conclusions, V. parahaemolyticus did not survive well during frozen treatment and low temperature storage (<;5°C). In addition, heating treatment (□60°C) is also effective to inactivate V. parahaemolyticus. Results of this study can be applied to reduce risks of infections associated with foodborne pathogen V. parahaemolyticus.