Abstract: Yak casein was used as the substrate,the content of free amino acids was used as evaluation index,six different enzymes,including trypsin,pepsin,papain,neutrase,alcalase and pancreatin,were used to hydrolysis casein under ultra-high pressure.The optimal process of casein hydrolysis was optimized by single factor analysis and orthogonal experiments.At the same time,the application of hydrolysates in animal cell culture was investigated.The results showed that pancreatin was more suitable for the hydrolysis of yak casein,the optimal process was as follows:substrate concentration 15%,E/S=1:5,hydrolysis pressure 150 MPa,temperature was 45 ℃,pH 7.5 and hydrolyzed for 8 h.Under these conditions,the content of free amino acids of hydrolysate was determined to be 52.18%.The hydrolysates did not appear any toxic to BHK-21 cells when supplemented in the medium,and cells growth well.The study can be served for the further exploitation and utilization of the yak casein and the application of protein hydrolysates in animal cell culture.

Key words: ultra-high pressure, enzymatic hydrolysis, casein, amino acids content, cell culture