Eco-sustainable production of bioactive peptides: Antioxidant and antihypertensive potential of Priacanthus hamrur fish skin waste hydrolysate using protamex enzyme.

Recycling fish processing waste is essential for improving the sustainability of industrial operations and advancing the circular economy. The present study aimed to assess the antioxidant and antihypertensive effects of Priacanthus hamrur skin waste protein hydrolysates produced by the protamex enzyme. Optimum conditions resulted in significant antioxidant activity with an enzyme concentration of 1.77 %, a hydrolysis duration of 35.33 min, a temperature of 50.75 °C, and a pH of 7.40 using a quadratic model equation. The protamex-mediated protein hydrolysate (PrMPH) had high protein with essential amino acids. UV-Vis spectral analysis exhibited significant absorption at 278 nm. Fourier transform infrared spectroscopy spectra revealed prominent peaks at 3281.24 cm-1, 1532.58 cm-1, and 1236.99 cm-1, corresponding to the stretching frequencies associated with hydroxyl and amide groups. X-ray diffraction study indicated a broad peak at approximately 2θ = 20.79°, indicating that it is amorphous. The differential scanning thermogram revealed the endothermic peaks at 94.24 °C, 179.98 °C, and 234.11 °C, indicating distinct thermal changes in the material. The antioxidative capability was dramatically enhanced (p < 0.05) by increasing the protein content. The Angiotensin-converting enzyme (ACE) inhibitory activity was 57.45 ± 0.53 % at a 2 mg/mL protein. This study presents PrMPH with significant antioxidant and antihypertensive effects, feasible in the nutritional, food, and pharmaceutical sectors.