Abstract: In this study,complex enzyme (pancreatin and neutral protease) hydrolyzed rennet casein was used to prepare lacto-protein hydrolysate.The process was optimized by orthogonal experiments.The effects of promoting cell growth of the lacto-protein hydrolysate were assayed by cultivating BHK and Vero cells.The results showed that the optimal processes of preparing lacto-protein hydrolysate was:pancreatin:neutral protease=2:1(mass ratio),40 ℃,pH 7.0,enzyme/substrate (E/S) =1:5 (mass ratio),hydrolysis time of 6 h.In the hydrolyzed product,the content of amino nitrogen was determined to be 3.21 g/L,peptide was 35.63 g/L,free amino acids was 14.17 mg/mL,the yield was 40.20%.In the 24 h lacto-protein hydrolysate cultured BHK and Vero cells,the cell densities were 2.0 times to respective blank control,1.0 and 0.86 times to Hyclone products;In the 48 h lactoprotein hydrolysate cultured BHK and Vero cells,the cell densities were 5.0 times and 4.0 times to respective blank control;and both 0.88 times to Hyclone products.Based these experimental results,it was concluded that the optimal preparation process was simple and short timeconsuming;the lactoprotein hydrolysate promoted cell growth for BHK and Vero cells.

Key words: lacto-protein hydrolysate, preparation, cell culture, application