Levels of Vibrio vulnificus and organoleptic quality of raw shellstock oysters (Crassostrea virginica) maintained at different storage temperatures

Temperature abuse during raw oyster harvesting and storage may allow for th e multiplication of natural spoilage flora as well as microbial pathogens, thus posing a potential health threat to susceptible consumers and compromi sing product quality. The objective of this study was to provide a scientif ic basis for determining whether different refrigeration and abuse temperat ures for raw oysters would result in a spoiled product before it became uns afe. Raw shellstock oysters (Crassostrea virginica) purchased from a commer cial Virginia processor were subjected to different temperature abuse condi tions (7, 13, and 21 degreesC) over a 10-day storage period. Salinity, pH, halophilic plate count (HPC), total culturable Vibrio counts, and culturabl e Vibrio vulnificus counts were determined at each abuse condition. V. vuln ificus isolates were confirmed by a specific enzyme-linked immumosorbent as say. Olfactory analysis was performed to determine consumer acceptability o f the oysters at each abuse stage. The pH of the oysters decreased over tim e in each storage condition. The HPC increased 2 to 4 logs for all storage conditions, while olfactory acceptance decreased over time. V. vulnificus l evels increased over time, reaching 10(5) to 10(6) CFU/g by day 6. The leng th of storage had a greater effect on the bacterial counts and olfactory ac ceptance of the oysters (P < 0.05) over time than did the storage temperatu re (P < 0.05).