Abstract: The aim of this study was to prepare umami peptides from the hydrolysis of a mixture of meat from 3 different species of aquatic products (silver carp, prawn and scallop) at a mass ratio of 1:1:1 with both flavourzyme and protamex at a mass ratio of 1:1. The hydrolysis process was optimized using response surface methodology based on a Box-Behnken experimental design. The effects of enzyme-to-substrate ([E]/[S]) ratio, hydrolysis temperature and hydrolysis time on degree of hydrolysis and sensory evaluations were explored. The optimal hydrolysis conditions were determined as follows: [E]/[S] ratio 7.5‰, substrate concentration 30 g/100 mL, natural pH, hydrolysis 56 ℃, and hydrolysis duration 5.9 h. Under these conditions, the degree of hydrolysis of aquatic products and the sensory evaluation score of the hydrolysate obtained were 56.32% and 6.8, respectively, close to the predicted values (55.17% and 6.9, respectively). The ultrafiltration of this hydrolysate resulted in 4 umami peptides. Maillard reaction products of each umami peptide with molecular weight between 2.5 kD and 5 kD showed a strong umami and non-bitter taste and no fishy odor.

Key words: umami peptide, enzymatic hydrolysis, ultrafiltration, Maillard reaction