Antioxidant and Antihypertensive Activities of Giant Grouper (Epinephelus lanceolatus) Egg Protein Hydrolysates

Fish eggs have been recognized as a potential source of bioactive peptides due to their high protein content. Accordingly, the utilization of roe by-products from the giant grouper as sources of biopeptides to increase their value appears to be feasible. This research aimed to identify the bioactivities of giant grouper roe, particularly on antioxidant and angiotensin-I-converting enzyme (ACE-I) inhibitory activities. Unutilized grouper roe was first defatted and subsequently hydrolyzed using pepsin (DFRpep), papain (DFRpap), and bromelain (DFRbro). The protein hydrolysates were then analyzed for their ACE-I inhibitory and antioxidantactivities. The results showed that the degree of hydrolysis after four hours was 26.25% for DFRpep, 12.66% for DFRpap, and 11.07% for DFRbro. Pepsin hydrolysates produced the highest yield at 59.99%, followed by papain (23.43%) and bromelain (17.09%), with protein contents of 91.46%, 73.03%, and 52.17%, respectively. At a concentration of 2 mg/ml, pepsin hydrolysates exhibited the strongest ACE-I inhibition, achieving 34.09 ± 1.83%, compared to bromelain and papain hydrolysates, which showed inhibitions of 31.15 ± 4.65% and 21.51 ± 1.41%, respectively. Additionally, grouper roe treated with papain and bromelain showed greater potential for DPPH scavenging activity at 21.36 ± 0.37% and a reducing power activity of 0.151 ± 0.040%, respectively, than pepsin hydrolysates. Based on these findings, giant grouper roe can be effectively utilized as a valuable raw material for producing specific bioactive peptides, such as ACE-I inhibitory and antioxidant peptides. These bioactive peptides can be formulated into pharmaceutical products to boost their market value and improve human health.