Functional Properties of a Peptide of 23 Residues Purified from the Peptic Hydrolyzate of asl‐CASEIN: Changes in the Emulsifying Activity During Purification of the Peptide

The pH 4.6‐soluble fraction of the peptic hydrolyzate of as 1‐casein contained the 23 N‐terminal residues, αsl‐CN(fl‐23), as a major pep‐tide. Reversed‐phase HPLC indicated that small amounts of other peptides such as αsl‐CN(f154‐199) were also contained in this fraction. By removing of these peptides, the emulsifying activity (EA) of the αsl‐CN(fl‐23) fraction was markedly decreased. However, when the removed peptide fraction was added to the purified αsl‐CN(fl‐23), the EA was increased. Some synergistic effect in the emulsification seemed to exist between αsl‐CN(fl‐23) and the other peptides. Although the purified αsl‐CN(fl‐23) had low EA values at neutral pH levels, it showed high emulsifying and surface activities in the acidic pH region.