Study on the Molecular Weight Distribution and Functional Activities of Several Tuna Protein Hydrolysates

Purpose - The present study aimed to enhance the high-value utilization of tuna protein through enzymatic hydrolysis, producing bioactive peptides with potential antioxidant and antihypertensive activities. The molecular characteristics of peptides derived from trypsin, alkaline protease, and dual-enzyme hydrolysis were examined to elucidate their structure-function relationships and bioactivity. Design/Methodology/Approach - Tuna dark meat was enzymatically hydrolyzed using three different protease: trypsin, alkaline protease, and dual-enzyme hydrolysis. The MALDI-TOF/TOF technique was utilized to determine the molecular weight distribution and identify dominant peptides. Bioactivity prediction was conducted using molecular docking to assess the antioxidant and ACE inhibitory potential, which was further validated through in vitro chemical assays Findings - Peptides below 1 kDa dominated, with those in the 0.5-3 kDa range exhibiting enhanced bioactivity due to hydrophobicity and aromatic amino acids. The dual-enzyme hydrolysate showed the strongest DPPH scavenging (IC50 = 0.2042 mg/mL) and ACE inhibition (IC50 = 2.321 mg/mL), surpassing individual enzyme treatments. Research Implications - This study provides valuable insights into the enzymatic preparation of bioactive peptides from tuna protein, demonstrating their potential applications in functional foods and nutraceuticals. The findings support the efficacy of enzymatic hydrolysis as a strategy for improving the antioxidant and antihypertensive properties of food-derived peptides. Future research should focus on mechanistic studies to elucidate peptide interactions with target proteins and evaluate their bioavailability and physiological effects in vivo.