Bifidobacterial growth–promoting effect of yak milk κ‐casein hydrolysates produced with different proteases

Summary The growth‐promoting effects of κ‐casein hydrolysates produced by four different proteases (trypsin, alcalase, papain and chymosin) on bifidobacteria ( B b12 and BBMN 68) viability were evaluated. Results showed that the obtained κ‐casein hydrolysates possessed better property for improving the viability of B b12 and BBMN 68 than native κ‐casein. The bifidobacterium viability and p H drop were dependent on the added hydrolysates. The addition of κ‐casein hydrolysates improved the viability of B b12 and BBMN 68 to a variable extent. The κ‐casein hydrolysate produced with papain ( KCHP ) is the best for B b12 and κ‐casein hydrolysate produced with trypsin ( KCHT ) is the best for BBMN 68. Proper amino acid profiles improved the viability of B b12 and BBMN 68. The bifidobacterial growth‐promoting capacity of κ‐casein hydrolysate may be due to its high content of A la, M et, T yr, P he and A rg residues, especially T yr which is richer in para‐κ‐casein than in casein glycomacropeptide ( GMP ). In addition, the sialic acid content of κ‐casein hydrolysate produced with the tested proteases did not show a direct relationship with its bifidobacterial growth–promoting effect. The obtained peptides possessed growth‐promoting activity for B b12 and BBMN 68 existed in para‐κ‐casein.