Recovery and Characterization of Keratin from Fish Scale Collagen Extraction Residue

In order to fully develop the economic value of fish scales, expand the source of keratin, in this study, the collagen-extracted grass carp fish scale residues were used as raw materials, single factor experiment and orthogonal experiment were used to determine the optimal extraction process of keratin, and the extracted fish scale keratin was characterized. The results showed that under the condition of 60 g pepsin in 1% citric acid solution at 4 ℃ for 24 h, the highest collagen removal ratew as obtained, with the best removal effect and structural integrit. The optimal process conditions for extracting grass carp scale keratin were as follows: Extraction temperature 60 ℃, sodium hydroxide concentration 9%, material-liquid ratio 1:12.5. The UV absorption peaks of fish scale keratin were at 218.2, 280.4 nm, respectively. SDS-PAGE electrophoresis showed that the apparent molecular weight of fish scale keratin was about 48 kDa. Infrared results showed that the secondary structure of keratin was α-helix, and the characteristics of amino acid components were basically the same as wool keratin.