Casein phosphopeptide monomers and preparation method thereof

The invention provides casein phosphopeptide (CPP) monomers and a preparation method thereof. Casein phosphopeptide CPP1, CPP2 and CPP3 which are high in calcium holding activity and have specific sequences are prepared by using casein in milk as a raw material, and performing trypsin digestion, enzyme deactivation, fine filtration, alcohol precipitation, centrifugation, chromatography through a sephadex column and a medium pressure column, reverse phase silica gel purification, drying and the like. The molecular weight of the CPP1 is 1224.12, the sequence of the CPP1 is SIGpSpSpSEEpSAEVATEEV, and the CPP1 belongs to 68-84 fragments of alpha s2 casein; the molecular weight of the CPP2 is 1082.14, the sequence of the CPP2 is IGpSEpSTEDQAMEDIK, and the CPP2 belongs to 59-73 fragments of alpha S1 casein; the molecular weight of the CPP3 is 1578.70, the sequence of the CPP3 is ELEELNVPGEIVEpSpSpSEESIT, and the CPP3 belongs to 17-39 fragments of beta casein. The liquidity of the products prepared by the method provided by the invention is high, a water solution of each 25% casein phosphopeptide is clear and transparent, the casein phosphopeptides are pure white powder, are small in molecular weight, conducive to absorption by a human body, large in number of phosphoserine residues and high in calcium holding activity, and can be applied to quality control of casein phosphopeptide products using the casein phosphopeptides, with the specific sequences, as active ingredients.