Refrigeration of Oyster Shellstock: Conditions Which Minimize the Outgrowth of Vibrio vulnificus

Abstract

The multiplication of Vibrio vulnificus in summer harvest oyster shellstock held without refrigeration was followed over a 14 h postharvest period. Mean (n = 7) increases were 0,75, 1.30, 1.74, and 1.94 log units at 3.5 h, 7 h, 10.5 h, and 14 h postharvest, respectively. Aerobic plate counts (spread plates on plate count agar [PCA] containing 1% NaCl, 25°C) but not standard plate counts (pour plates, PCA, 35°C) showed a similar trend in increase. Reducing the time oyster shellstock remains outside refrigeration can decrease consumer exposure to high numbers of V. vulnificus , but shellstock must be cooled immediately after harvest to eliminate postharvest growth of this bacterium.

Keywords: aerobic plate count; oysters; time/temperature abuse.