Effects of immersion salinity on the food properties of shucked oysters

The effects of immersion salinity on the food properties [water content, salinity, and free amino acid (FAA) content] of shucked oysters were analyzed. Results of a laboratory immersion experiment suggested that the molluscous parts (other than the adductor muscle) swelled in lower salinity and shrank in higher salinity. Higher FAA content was observed in oysters immersed in higher-salinity water. In the adductor muscle, water content increased and FAA content decreased markedly following immersion, regardless of salinity, probably because of intake of immersion fluid and leakage of FAAs across the cut end of the adductor muscle. Immersion salinity ranged from 0.17 to 1.54 % in shucked oyster products on the retail market. Tissue salinity was strongly correlated with immersion salinity (r = 0.904), and tissue water content was correlated negatively with immersion salinity (r = ?0.668). In addition, total FAA and taurine content of oysters were correlated with immersion salinity (r = 0.629 and 0.865, respectively). These results clearly indicate that immersion salinity is an important factor affecting the food components of shucked oysters.