Bioactive properties of enzymatic hydrolysates from abdominal skin gelatin of yellowfin tuna ( T hunnus albacares )

Summary Gelatin (90.6 ± 0.1%) was optimally prepared by response surface methodology from yellowfin tuna ( Thunnus albacares , YT ) abdominal skin. To investigate bioactive properties of enzymatic hydrolysates from the abdominal skin gelatin ( ASG ), ASG was hydrolysed with alcalase, protamex, neutrase and flavourzyme as affected by hydrolysis time. Antioxidant, nitrite scavenging and angiotensin‐I converting enzyme ( ACE ) inhibitory activities of the hydrolysates were determined. Antioxidant activities of the hydrolysates were found through linoleic acid peroxidation inhibitory effects. Alcalase‐derived hydrolysates ( AH s) were more effective than others in metal ions chelating, superoxide anion scavenging and hydroxyl radical scavenging activities ( P  < 0.05). AH s showed significantly stronger nitrite scavenging activities (44.4–60.7%) than others ( P  < 0.05). Fraction A from AH showed strong ACE inhibitory activity ( IC 50 of 0.75 mg mL −1 ). These results suggest that YT ASG and its enzymatic hydrolysates could be functional food and/or pharmaceutical ingredients with potent antioxidant, anticarcinogenic and antihypertensive benefits.