Salt-Reduced Fish Sauce Produced under Pressurized Carbon Dioxide Treatment Using Sardinops melanostictus, Trachurus japonicus, Konosirus punctatus, Odontamblyopus lacepedii, Their Collective Mixture, and Unused Fish Mixture

Fish sauce is produced at high salt concentrations (>20%) to inhibit the growth of harmful microorganisms. The salt-reduced fish sauce (10% salt) was prepared under pressurized CO₂ (pCO₂) conditions at 30 °C and 5 MPa for 3 months (FSCO2), from <i>Sardinops melanostictus</i>, <i>Odontamblyopus lacepedii</i>, <i>Trachurus japonicus</i>, <i>Konosirus punctatus</i>, and their collective mixture, as well as unused fish mixture obtained from the Ariake Sea in Japan. FSCO2 exhibited significantly better microbial quality and free amino acid content, lighter color, standardized odor (dashi-like odor), and umami richness qualities compared to fish sauces prepared using the conventional method (FScon) (20% salt), as previously demonstrated, after a fermentation period of 2 months. Bacterial flora analysis implied that the standardization of odor and umami richness may not be the result of specific microbial metabolism. Even when using previously unused fish, it was possible to produce FSCO2 equivalent to that produced by conventional sardines and other fish. These results indicate that the quality of fish sauce can be improved. The flavor of FSCO2 became similar regardless of the type of fish and fermentation period using pCO₂ during fermentation, leading to the effective utilization of unutilized fish as a resource for high-quality salt-reduced fish sauce.