Effects of Acid and Enzymatic Extraction on the Structure and Physicochemical Characterization of Collagen from Chinemys reevesii Skin

This study investigated the effects of different extraction methods on the structure and physicochemical characterization of collagen extracted from the skin of Chinemys reevesii. Collagen from Chinemys reevesii skin was obtained using acid and enzymatic extraction methods. The composition, structure, and physicochemical characteristics of acid-soluble collagen (ASC) and enzyme-soluble collagen (PSC) were determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), high-performance liquid chromatography (HPLC), circular dichroism spectrometry (CD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), solubility, sensory evaluation, and chroma. ASC and PSC extraction yields were 24.50%±0.44% and 51.68%±0.06% respectively, with PSC demonstrating significantly higher extraction yield than ASC (P<0.05). Both ASC and PSC comprised α₁ and α₂ chains and exhibited a distribution pattern typical of type Ⅰ collagen. The content of glycine in ASC and PSC was the highest, 370.17 and 387.75 residues/1000 amino acid residues, respectively. ASC and PSC exhibited similar secondary structures, according to their comparable characteristic absorption peaks. The thermal denaturation temperatures of ASC and PSC were 27.21±0.28 ℃ and 28.37±0.23 ℃, respectively. SEM images indicated a disordered fiber state in the microstructure of ASC, whereas the microstructure of PSC exhibited a more uniform pattern. The solubility of ASC was slightly lower than that of PSC, and PSC had better sensory evaluation and chroma than ASC.