Physicochemical characteristics and metabolite composition of fish sauce made from large yellow croaker roe enzymatic hydrolysates based on three fermentation temperatures

Large yellow croaker roes were used to make fish sauce using enzymolysis method, and the impact of different fermentation temperatures (25, 32 and 40 degrees C) on the physicochemical characteristics and metabolite composition was revealed. Results indicated that compared with 25 and 32 degrees C, the higher contents of total acidity, amino nitrogen, total soluble nitrogen, and the deepening of the nonenzymatic browning degree of fish sauce fermented at 40 degrees C were obtained. The total volatile basic nitrogen content at 40 degrees C was lower than 32 degrees C. The ideal fermentation temperature should be 40 degrees C. The metabolomics analysis of fish sauce showed that 40 degrees C significantly increased the abundance of hippuric acid, 3-hydroxy hippuric acid, hydrocinnamic acid and heptanoic acid compared with other temperatures, but decreased trimethylamine N-oxide, 15-methyl palmitic acid, N6- succinyl adenosine and nicotinamide. These results expand the utilization pathways of low-value fish roes, and provide a promising reference for the manufacturing of high-quality fish sauce.