Fish skin gelatin hydrolysates produced by visceral peptidase and bovine trypsin: Bioactivity and stability

• Yielded peptides with ACE inhibitory and antioxidant properties.
• ACE inhibition activity remained stable in a wide range of pH.
• Radical scavenging activities increased with gastrointestinal tract model simulated.
• Visceral peptidase could be replaced to some commercial proteases.

The peptidase from the viscera of farmed giant catfish was used for producing gelatin hydrolysates (HG) and compared with those produced from commercial bovine trypsin (HB). The degree of hydrolysis (DH) observed suggests that proteolytic cleavage rapidly occurred within the first 120 min of incubation, and there was higher DH in HG than in HB. HG demonstrated the highest ACE-inhibitory activity, DPPH, ABTS radical scavenging activity, and FRAP. HB showed the highest FRAP activity. The DPPH radical scavenging activity of HG was quite stable over the pH range of 1–11, but it increased slightly when the heating duration time reached 240 min at 100 °C. The ACE-inhibitory activity of HG showed the highest stability at a pH of 7, and it remained very stable at 100 °C for over 15–240 min. The visceral peptidase from farmed giant catfish could be an alternative protease for generating protein hydrolysates with desirable bioactivities. The resulting hydrolysates showed good stability, making them potential functional ingredients for food formulations.