Accelerated production of reduced-salt sardine fish sauce under pressurized carbon dioxide, combining mild heating and proteolysis

Abstract

Fish sauce is a liquid condiment prepared by fermenting fish at room temperature and high salt concentration (> 20%) for more than six months. We examined whether the application of pressurized CO₂ (pCO₂), mild heating, and acid protease (1%) would produce reduced-salt fish sauce in a short fermentation period. Optimal fermentation temperature and NaCl concentration were determined to be 45°C and 7%, respectively, at a fixed fermentation period (one week). Treatment with pCO₂ (1 MPa), mild heating (45 °C), and acid protease (ORYENTASE AY) decreased biogenic amine content, increased free amino acid content, and enriched umami flavor. This treatment did not induce bacterial growth, and the changes in organic acid content and smell were minimal. In the presence of protease, browning was suppressed under pCO₂ compared to atmospheric pressure. Thus, the application of pCO₂ and protease with mild heating enabled reduced-salt fish sauce production in a short fermentation period.