Physicochemical properties of skin gelatin from farmed Amur sturgeon (Acipenser schrenckii) as influenced by acid pretreatment

Physicochemical properties of Acipenser schrenckii skin gelatin were determined as a function of acid pretreatment. Yield and gel strength of gelatin were decreased as the acid concentration and pretreatment time increased (P<0.05). FTIR spectra of all gelatins showed a significant loss of the triple-helix (Amide III/Amide 1450 wavenumber ratio less than 1) which indicated the conversion of collagen to soluble gelatin. Amide I absorption peak of gelatin obtained with higher acid concentration for longer soaking time appeared at higher wavenumber, compared to those obtained with lower acid concentration and time. All gelatins contained α-chains and β-chains as the predominant components. The hydroxyproline content, gelling and melting temperatures of gelatin were 6.1 g/100 g, 14 and 22 °C, respectively. The gelling and melting temperatures were intermediate between those of cold-water and warm-water fish gelatins, partly due to the differences in culture water temperature. The suitable acid concentration and pretreatment time were obtained as 0.05 M and 3 h, providing the good yield and gel strength.