Optimization of koji-making technology for preparing fish sauce and its fermentation of blue scad

Using low-value fish, bran and wheat flour as raw materials, fermentation technology of low-salt liquid-state fish sauce was researched by adopting only one kind of bacterium koji-making. Using the contents of enzyme active of neutral protease and the amino nitrogen as indexes, according to single factor tests and response surface method, the optimum koji-making conditions were as follows:material rate was 8∶2, adopting bacterium was 0.9%, cultural time was 36h, and cultural temperature was 35℃. Under this optimal condition, the neutral protease activity was as high as 1130.85U/mL. The fermentation technology conditions of fish sauce were as follows : adding fish liquid koji- making was 10 %, salinity was 15 %, material rate was 1 ∶ 1, and fermentation temperature was 37℃. Under such conditions, the content of amino nitrogen reached 0.681g/100mL and the content of total soluble nitrogen also could reach 0.695g/100mL after 14d. In addition, red-brown and transparent, no suspension and no precipitate were the major characteristics of the fish sauce prepared at optimal fermentation condition. This study showed that the fish liquid koji-making could reach low-salt liquidstate fish sauce.