Abstract: Based on one-factor-at-a-time experiments, orthogonal array design method was employed to optimize the preparation of flavorful sauce from freshwater fish by-products by enzymatic hydrolysis followed by fermentation. The highest degree of hydrolysis was achieved when a mixture of flavorzyme and alcalase at a ratio of 1:1 was added at a dose of 0.25 g/100 g for 4 h of hydrolysis at 55 ℃ and pH 7.5. The hydrolysate was completely deodorized after 1 h of fermentation at 35 ℃ with yeast at an inoculum size of 2.0 g/100 g. The Maillard reaction products of the fermentation broth obtained after reaction at 115 ℃ for 40 min in the presence of a mixture of xylose and glucose (1:3) at a concentration of 4 g/100 g and L-cysteine hydrochloride at 1.0 g/100 g showed the highest sensory score. The flavorful sauce obtained revealed a strong meat and sauce flavor and no fishy odor. The free amino nitrogen content was 0.86 g/100 mL. Thus, it is a natural seasoning with great development potential.

Key words: freshwater fish, by-products, enzymatic hydrolysis, fermentation, Maillard reaction, sauce