Abstract
Sodium chloride-soluble collagen (SSC), acetic acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were extracted from the skin of chicken feet and then characterized. PSC, ASC and SSC showed the yields of 49.10%, 14.49% and 1.13% (Based on lyophilized dry weight), respectively. PSC, ASC and SSC were characterized as type I collagen, containing α1 and α2 chains as well as β and γ-chains. Circular dichroism (CD) and Fourier transform infrared (FTIR) spectra of PSC, ASC and SSC were similar, suggesting that they maintained their intact triple helical structure. PSC, ASC and SSC contained Gly as the major amino acid with high contents of Glu, Ala, Pro and Hyp. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of PSC, ASC and SSC revealed that their surface topography were similar. Dynamic elastic behavior in PSC, ASC and SSC was detected. PSC showed the largest elasticity. Temperature sweeps test indicated that PSC had the highest denaturation temperature, followed by ASC, and then by SSC. Proline hydroxylation of PSC was higher (45.8%) than that of ASC, and SSC and accordingly PSC showed the highest thermal stability. PSC showed the highest degree of hydrolysis compared to ASC and SSC.
•Salt, acid and pepsin soluble collagens were isolated from skin of chicken feet.•All collagens were of type I with intact triple helical structure.•Protein surface in all collagens was characterized by bulky fiber bundles.•Pepsin collagen was superior in dynamic elasticity, thermal stability and DH.•Pepsin collagen had unique rheological properties due its high imino acids content.