Study on the extraction and functional properties of collagens from the skin of Chinese giant salamander and its digestibility in vitro

The in vitro digestion of the Chinese giant salamander skin was evaluated. The Box- Behnken design response surface test was used to optimize the extraction process of the collagen of the Chinese giant salamander skin.The functional properties of the collagen were also studied.The results showed that: the in vitro digestion of the Chinese giant salamander skin had reached 96.66%.The optimal condition for the extraction were the combination of adding 1000 U / m L of enzyme,33 h of extraction and 12 min of ultrasonic.The yield reached 71.94%,similar with the model predicted value( 73.32%).Under the condition of 20 ℃ and 43% and 81% RH,20% of water could be hold for a long time.The pepsin soluble collagen( PSC) had the best foaming ability when the protein concentration was 0.4 g /100 m L,p H7 and the salt ion concentration was 1.25 mol / L.When p H was 4,salt ion concentration was0.25 mol / L,the salamander skin collagen had the best emulsibility.