Characterization and comparison of hydrolyzed collagens obtained from the processing wastes of cultured sea bass (dicentrarchus labrax) and sea bream (sparus aurata) fish

In this study, collagen hydrolysates were obtained from the processing by-products (skin/bones) of seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata), which are widely farmed in Türkiye. These hydrolysates were characterized, compared with each other, and their potential applications in the food, cosmetic, pharmaceutical, and biomedical sectors were revealed. The degrees of hydrolysis were determined as 98.82% for seabass skin collagen hydrolysate (LDKH), 97.49% for seabream skin collagen hydrolysate (ÇDKH), 96.82% for seabream bone collagen hydrolysate (ÇKKH), and 90.31% for seabass bone collagen hydrolysate (LKKH). SDS-PAGE analysis showed that the molecular weights of the hydrolysates were approximately in the range of 1–6 kDa. FTIR analysis confirmed that all collagen hydrolysates exhibited characteristic bands of hydrolyzed collagen (Amide A, B, I, II, III). SEM observations revealed that the hydrolysates possessed wrinkled, layered, and fibrous structures. In DSC analysis, the highest denaturation temperature was recorded in the ÇDKH sample (113,27°C). XRD measurements indicated diffraction peaks representing the regular molecular arrangement of the triple-helical structure in collagen hydrolysates. All hydrolysate samples exhibited moderate antibacterial activity against the Gram(+) Staphylococcus aureus ATCC 43300 (MRSA) strain. Regarding DPPH radical scavenging activity, a concentration-dependent increase was observed. The highest activity was detected in the LDKH sample at 5 mg/ml (51.86%), followed by ÇKKH (48.57%), ÇDKH (41.48%), and LKKH (33.80%). Cell culture studies demonstrated that the LKKH samples significantly enhanced cell viability at 500 µg/ml after 24 h, and at 200 µg/ml after 48 h and 72 h. The effects of ÇKKH on cell viability were found to vary significantly depending on both the exposure time and the applied concentration.