Structural characterization and enzymatic hydrolysis of tilapia skin and scale gelatin: Antioxidant properties and peptide profiling of hydrolysates

Enzymatic hydrolysis of gelatin from tilapia skin and scales is a promising approach to enhancing the value of fishery waste. In this study, gelatin was extracted from tilapia skin and scales, followed by an analysis of their amino acid composition and secondary structures. Both samples (SCG: skin gelatin, SKG: scale gelatin) exhibited characteristic gelatin structure, with minor variations observed: SCG demonstrated a greater β-sheet content and higher levels of proline and hydroxyproline, indicating a more stable structure. In addition, the degree of hydrolysis (DH) and antioxidant activities of the gelatin hydrolysate generated using different enzymes were investigated. The enzymatic hydrolysates with high DH, including SCG-Alkaline protease (19.2 %), SCG-Trypsin (17.3 %), SKG-Trypsin (18.8 %), showed better antioxidant activities. Peptide profiles analyzed by LC-MS/MS revealed the SCG-Alkaline protease hydrolysate, which exhibited the highest antioxidant activity, contained the largest proportion of small peptides (0–2 kDa). Different sources of gelatin may lead to variations in the functional characteristics of enzymatically hydrolyzed peptide segments owing to structural differences. By analyzing enzymatic hydrolysis tendencies, this study established a theoretical foundation for screening efficient proteases and targeting the release of specific functional peptides, supporting the development of functional foods. • Gelatin was successfully extracted from tilapia skin and scales. • Structural properties of skin and scale gelatins were compared. • Eight gelatin hydrolysates were screened for degree of hydrolysis and antioxidant. • Peptide profiling by LC-MS reveals effects of source and enzymes on hydrolysates.