Abstract: This study aimed to establish a new method to extract and separate flavor compounds from small trash fish, improving the added value of the resource and realizing its in-depth development and utilization. The method was based on bio-enzymatic hydrolysis and magnetic ultrafiltration membrane separation and the magnetic ultrafiltration membrane used was prepared by in situ synthesis from polysulfone ultrafiltration membrane with a molecular weight cut-off (MWCO) of 2000. Selective separation was achieved for umami small peptides small peptides in small trash fish hydrolysate. The difference in the composition of flavor compounds in small trash fish hydrolysates prepared with flavourzyme in combination with trypsin, papain, neutrase or alcalase was evaluated based on the percentage of umami amino acids in total amino acids, and the results showed that the combination of flavourzyme and alcalase provided optimum hydrolysis of small trash fish. Using orthogonal array design, the optimal conditions for the application of both enzymes to hydrolyz small trash fish was optimized to be: 2350 U/g alcalase dosage, 700 U/g flavourzyme dosage, 1:10 material/liquid ratio, 55 ℃ and 6 h. The optimized hydrolysate was rich in umami peptides and umami amino acids with a yield of 6.43%. This study suggests that magnetic ultrafiltration membrane separation enables the selective separation of flavor compounds.

Key words: low value small fish, enzymatic hydrolysis, magnetic ultrafiltration membrane, umami amino acid