Effects of different methods on physico- chemical properties of collagen deprived from Rana chensinensis (Rana dybowskii) skins

Rana chensinensis skins as raw materials,two methods,being acid and pepsin respectively,were used to prepare collagen,eventually,getting two collagens: acid- solubilized collagen( ASC) and pepsin- solubilized collagen( PSC),of which physico- chemical properties and functional characteristics were compared and studied.Results showed that there was a strong absorption peak at 234 nm by analyzing UV spectrums,which demonstrated the two kinds of collagens were in accordance with collagens,characteristics.ASC and PSC had absorption peaks at3346.0,2952.0,1662.0,1548.0,1242.0 cm- 1and 3322.0,2944.0,1662.0,1551.0,1236.0 cm- 1respectively by analyzing IR spectrums,which proved the existences of amide A,amide B,amideⅠ,amideⅡ,amide Ⅲ,indicating that triple helical conformation of the two kinds of collagens were reserved completely. According to analyze amino acids compositions,there were 18 kinds of amino acids in ASC and PSC,including 8 kinds of necessary amino acids humans need,of which were a little different between ASC and PSC. SDS-PAGE electrophoresis results showed that both collagen existed β,α1and α2chain,in line with structural features of collagen typeⅠ.Compared with ASC,PSC was higher in denaturation temperature,but was lower in moisturizing efficiency,there were not significant for them in moisture absorption rate and the relative solubility( p < 0.05).These results described above suggested that different extraction methods have certain influence on the structure,functional characteristics of collagen from Rana chensinensis skins,but did not affect the quality of collagen.