Abstract: Acidic and enzymatic extraction methods were separately used to extract collagen from yak bone and the physicochemical properties of the obtained collagens were compared. Their amino acid compositions were analyzed and their structures were determined by using UV spectroscopy, Fourier transform infrared spectroscopy (FTIR), heat shrinkage temperature, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscopy (SEM). The extracts were characterized as collagens, showing maximum UV absorption peak at 230 nm. The heat shrinkage temperatures of acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were 40.12 and 40.94 ℃, respectively, and their denaturation enthalpies were 0.25 and 0.22 J/g, respectively. FTIR and SDS-PAGE analyses demonstrated that ASC and PSC were mainly composed of α, β and γ subunit components, which both belonged to type I collagen with a complete three-strand helical structure. SEM revealed that ASC and PSC retained a relatively complete fibrous network structure, but the structure of ASC was more evenly distributed. There was no significant difference in the physiochemical properties of the two collagens, while the enzymatic extraction method gave a higher yield of collagen but was more expensive than acidic extraction.

Key words: yak bone, collagen, acidic extraction method, enzymatic extraction method