Green and Sustainable Production of Bioactive Protein Hydrolysates from Hilsa (Tenualosa ilisha) Using Ultrasound-Assisted Subcritical Water Hydrolysis

Abstract

Hilsa muscle biomass was hydrolyzed to recover bioactive proteins and peptides using subcritical water hydrolysis (SWH) with ultrasound pretreatment at various temperatures (150–250 °C) and pressures (40–80 bar). Hydrolysis yield was increased with rising temperature and pressure, with the highest yield (98.70 ± 0.60%) observed at 250 °C and 80 bar using SWH with ultrasound pretreatment (UPT). The properties of the hydrolysates—including pH, taurine content, and color values—were influenced by the hydrolysis conditions. Additionally, total protein content, reducing sugar levels, antioxidant activity, foaming capacity (FC), and foaming stability (FS) increased at higher temperatures and pressures. Hydrolysates prepared at 225 °C and 70 bar, as well as at 250 °C and 80 bar, contained highly bioactive peptides and molecules that exhibited inhibitory effects on hydroxyl radicals and prevented λ DNA degradation. The highest 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) activities were observed in hydrolysates obtained at 225 °C and 70 bar with ultrasound pretreatment, reaching 96.88 ± 0.26% and 76.36 ± 2.84%, respectively. Amino acid profile analysis showed that the greatest number of amino acids (eight) was detected in hydrolysates produced through SWH at 250 °C and 80 bar. Overall, SWH combined with ultrasound pretreatment markedly enhanced yield and biofunctional properties of hilsa protein hydrolysates, highlighting their potential applications in food, pharmaceutical, and cosmetic industries.