Ultrasonic-assisted enzymatic hydrolysis of Perinereis aibuhitensis using the RSM–BP–GA model

The lack of ultrasound-assisted hydrolysis techniques often limits the efficacy of Perinereis aibuhitensis protein hydrolysate. Therefore, using P. aibuhitensis as the raw material and a 1:1 mix of neutral protease and flavour protease as the composite enzyme, we evaluated the degree of hydrolysis (DH). We systematically optimised the conditions for ultrasound-assisted enzymatic hydrolysis of P. aibuhitensis proteins using single-factor experiments, the response surface method, and a back-propagation neural network integrated with a genetic algorithm. The optimal hydrolysis conditions were as follows: a liquid-to-material ratio, 1:2.5; enzyme concentration, 970 U/g; ultrasound power, 390 W; sonication time, 31 min; enzymolysis temperature, 50 °C; ultrasound frequency, 30 kHz; pH, 7; and hydrolysis duration, 3 h. Under these conditions, compared to non-ultrasound composite protease hydrolysis, the flavour of P. aibuhitensis ultrasound-assisted enzymatic hydrolysate significantly improved (umami and richness enhanced, bitterness and bitter aftertaste reduced). Anticoagulant activity, DPPH and ABTS radical scavenging rates reached 60.09 U/g, 58.94 %, and 71.03 %, increasing by 0.26-, 0.10-, and 0.15-fold, respectively, potentially due to the increased content of flavour compounds. Specifically, Asp, Glu, Gly, Pro, AMP, IMP, and GMP concentrations increased by 0.18-, 0.15-, 0.15-, 0.23-, 0.27-, 0.13-, and 0.27-fold, respectively. Moreover, P. aibuhitensis peptide yield reached 31.14 % (0.24-fold increase), generating more small-molecule active peptides. Polysaccharide yield reached 1.87 % (0.23-fold increase), and the DH reached 38.57 % (0.50-fold increase). Reaction time was reduced by 29 min compared to that using other methods. Overall, this study provides a robust theoretical foundation for developing P. aibuhitensis-based food products and pharmaceuticals.