Abstract: This paper deals with the optimization of conditions for the enzymatic hydrolysis of Apostichopus japonicus spawn to obtain maximum degree of hydrolysis (DH). Papain, protamex and flavourzyme were found to be more suitable for the hydrolysis of Apostichopus japonicus spawn. Process parameters for the hydrolysis of Apostichopus japonicus spawn by each of the selected enzymes including temperature, enzyme dosage and time were optimized by one-factor-at-a-time and orthogonal array design methods. Meanwhile, the combined use of these enzymes was investigated. Based on DH, production cost and sensory quality of Apostichopus japonicus spawn hydrolysate, the optimal hydrolysis procedure was determined as follows: hydrolysis at 75 ℃ for 4 h with a 1:1 (m/m) mixture of papain and protamex at a total enzyme dosage of 2.0% and after boiling for enzyme inactivation, further hydrolysis with 1.5% flavourzyme at 45 ℃ for 1 h. Under these conditions, the DH was 77.11% and the obtained hydrolysate had a strong aroma and delicious taste and was a homogeneous and clear liquid. Therefore, it can be applied in functional foods with unique flavor.

Key words: Apostichopus japonicus spawn, hydrolysis, degree of hydrolysis, sensory evaluation, optimization