Physical and chemical properties of gelatin from the skin of cultured Amur sturgeon (Acipenser schrenckii )

To expand the usefulness of cultured Amur sturgeon, Acipenser schrenckii, its skin was used to explore the production of gelatin. After acetic acid pre-treatment (0.05 m for 3 h), gelatin was extracted at temperatures of 50 or 70°C for 1 or 6 h. Gelatin yield ranged from 9.42 to 12.47% (wet weight basis) (P < 0.05). With increasing extraction time and temperature, the content of imino acids (proline + hydroxyproline), gel strength and L*-value (lightness) decreased, while the a*-value (redness) and b*-value (yellowness) of gelatin gel increased (P < 0.05). Electrophoretic analysis revealed that α-chains and β-chains were predominant components in all extracted gelatins. Higher molecular weight proteins (γ-chain) were also observed. Gelling and melting temperatures of gelatin were 13.6–14.6°C and 20.3–22.6°C, respectively. Circular dichroism (CD) spectra and Fourier transform infrared (FTIR) spectroscopy revealed the triple helix loss in gelatin (A1235 (AIII)/A1451 < 1). Extraction conditions caused secondary structure changes in the gelatin. More likely due to the differences in the culture water temperature, gelatin exhibited gelling and melting temperatures intermediate between those of cold- and warm-water fish gelatins. The obtained gelatin can be used in food products or in the production of bioactive compounds.