PLASMIN HYDROLYSIS OF BETA-CASEIN - FOAMING AND EMULSIFYING PROPERTIES OF THE FRACTIONATED HYDROLYSATE

Bovine beta-casein (beta CN) was hydrolyzed by plasmin. The hydrolysat e was fractionated by ultrafiltration and selective precipitation, whi ch resulted in several peptide fractions of which the peptide composit ion was monitored by reversed-phase high-performance liquid chromatogr aphy. Poorly soluble, hydrophobic peptide fractions, containing peptid es from the C-terminal half of the beta CN sequence, possessed improve d foam-forming and -stabilizing properties compared to those of intact beta CN, especially at pH 4.0. Soluble peptide fractions, containing a variety of peptides from the ''middle'' part of the beta CN sequence in different proportions, possessed improved emulsion-forming capacit y at pH 6.7, compared to that of intact beta CN, and showed large vari ations in emulsion stability. The fraction containing the hydrophilic N-terminal part of beta CN showed inferior foam, emulsion, and surface -active properties, especially at pH 6.7. The differences in functiona lity found between the various peptide fractions may be attributed eit her to synergistic effects between peptides or to a specific functiona lity of some individual peptides.