Bioconversion of Eel Skin Waste into Valuable Collagen: Isolation, Spectral Characterization, and Biocompatibility Assessment

The current investigation was carried out to evaluate the structural and cell proliferation capability of pike conger eel collagen derived by the acid and enzymatic extraction methods. The recovery yield of pepsin soluble collagen (PSC) (40.65%) was significantly higher (p < 0.05) than acid soluble collagen (ASC) (29.9%) on a dry weight basis. In terms of molecular weight pattern, α₁ and α₂ bands of extracted collagen occurred to be 130KDa and 112KDa and were confirmed as Type 1 structures. The presence of characteristics peaks of amide bands in Fourier Transform Infrared Spectra (FTIR) and the d value of 12.28 Å and 11.37 Å in X-ray diffraction (XRD) revealed no significant changes in the highly ordered intact triple helical structure of collagen through pepsin digestion. The higher thermal stability with denaturation temperature of 33.3 °C for ASC and 35.1 °C for PSC was well documented in the differential scanning calorimetry (DSC) curve which showed a substantial correlation with the findings of imino acid content of both ASC and PSC collagen (203.5 ± 1.06 and 216.81 ± 0.32 residues/1000 g respectively). In addition, the nontoxic behavior of isolated collagen samples to L929 fibroblast cell lines emphasized the possible utilization of pike conger eel skin as a safe source of thermal stable collagen.