Functional properties and antioxidant activities of protein hydrolysates from orangefin ponyfish (Photopectoralis bindus)

Amino acid profiles, functionality, and antioxidative potential of orangefin ponyfish (Photopectoralis bindus)protein hydrolysates, using 1% alcalase, with diverse hydrolysis times (1, 2, 3 and 4 h), were evaluated. The samples solubility in the pH range of 3-9, emulsifying and foaming properties at various protein contents (2.5, 5 and 10 mg/mL), as well as the scavenging of DPPH, ABTS free radicals and reducing power (at concentrations of 1-5 mg/mL), were studied. The amino acid profile of orangefin ponyfish was used to estimate nutritional value. A high amount of essential amino acids (35%) involved in protein hydrolysates and Glx, Asx, and Gly were the dominant amino acids. Solubility was above 90% in the pH range 3-9 and increased at all hydrolysis times by changing the pH from acidic to alkaline (p<0.05). The emulsifying activity (EAI) and stability (ESI) indices were reduced with increasing hydrolysis; at 2.5 mg protein/mL, 1 h hydrolysates displayed the highest EAI (87±2 m2/g) and ESI (22±0.4 min), when considered with those possessing higher hydrolysis time. On the other hand, the foam expansion and stability increased with increasing hydrolysate content. Antioxidant activity of hydrolyzed protein increased with increased hydrolysis (up to 3 mg/mL), especially DPPH and ABTS. However, the highest DPPH and ABTS scavenging activity of FPH was about 73% and 93% at 5 mg/mL hydrolysate concentration and hydrolysis time 4 h, respectively.