Emulsifying Peptides from the Tryptic Hydrolysis of Casein

Casein was hydrolyzed by trypsin to 5% degree of hydrolysis, and the hydrolysate was fractionated by ultrafiltration. While screening for the best emulsifying properties, the retentate fraction was systematically fractionated by ammonium sulfate precipitation, ion exchange, and reverse‐phase high‐performance liquid chromatography (HPLC). Residue from 30% ammonium sulfate saturation yielded 3 fractions on anion exchange chromatography. Preparative reverse‐phase HPLC was used to isolate 4 peptides with good emulsifying properties for characterization. Computational methods were used to complement amino acid sequencing, and the peptides were identified as originating from αs‐1 casein (f167‐208), β‐casein (f48‐63), and (f129‐184). A 4th peptide could not be conclusively identified. Properties of the emulsifying peptides are discussed.