Process optimisation for preparation of caseinophosphopeptides from buffalo milk casein and their characterisation

Caseinophosphopeptides (CPPs) are multifunctional bioactive peptides containing phosphorylated seryl residues in their sequence. In the present study, method for the production of CPPs from buffalo milk casein was optimised and characterised for their sequence, calcium solubilising and calcium binding activities. Response surface methodology was used to optimise the conditions for hydrolysis of buffalo casein by trypsin to obtain maximum yield of CPPs. The optimum hydrolysis conditions were as follows: hydrolysis pH 7.5, temperature 37 °C, hydrolysis time 7.0 h. Under these conditions, the experimental yield obtained was 10.04±0.24%, which is slightly lower than value predicted by the model. These CPPs were able to solubilise 1.03±0.08 mg la/mg CPPs in presence of excess phosphate and bind 0.935 mg of Ca/mg of CPPs. Eight phosphopeptides, i.e., α(s1)-CN f (37-58) 2P; α(s1)-CN f (37-58) 3P; α(s1)-CN f (35-58) 2P; α(s1)-CN f (35-58) 3P; α(s2)-CN f (2-21) 4P; α(s2)-CN f (138-149) 1P; β-CN f (2-28) 4P and β-CN f (33-48) 1P were identified by LC-MS/MS which contained motif for binding of divalent minerals. The sequences of these CPPs differed from that of derived from bovine casein.