Experimental Seafood Processing Laboratory, Coastal Research & Extension Center, Mississippi State University, Pascagoula, MS, USA.
This study evaluated the efficacy of grape seed extract (GE), citric acid (CA) and lactic acid (LA) on the inactivation of Vibrio vulnificus and inherent microflora in fresh shucked oysters. The minimum inhibitory concentration (MIC) of GE, CA or LA against V. vulnificus was determined. Furthermore, the shucked oysters were artificially inoculated with V. vulnificus. The inoculated shucked oysters (25 g) were then dipped in 250 ml GE, CA or LA solutions for 10 min. The population of V. vulnificus in shucked oysters was determined. The effects of the treatments with GE, CA or LA solutions on the inherent microbiota in fresh shucked oysters during storage at 5°C for 20 days were also studied. The MICs of GE, CA or LA against V. vulnificus were 10·0, 5·0 or 1·0 mg ml−1, respectively. The concentrations of 500, 300 or 150 mg ml−1 GE, CA or LA solutions were needed to reduce the population of V. vulnificus to below the detection level (1·0 log g−1). Treatment with 500, 300, 150 mg ml−1 GE, CA or LA significantly reduced the initial inherent microbiota in fresh shucked oysters, and inherent levels were significantly (P < 0·05) lower than the control sample throughout refrigerated storage for 20 days.