Emulsifying and oil-binding properties of bovine serum albumin and its enzymatic hydrolyzate.

Bovine serum albumin (BSA) was hydrolyzed with proteases, and the emulsifying and oil-binding properties of the hydrolyzates were then studied. By limiting hydrolysis with trypsin, the emulsifying activity index (EAI) increased about 40% above its original level. In order to find out which peptides contributed to the good emulsifying properties of the hydrolyzate, the peptides adsorbed onto the emulsified oil globule surface were extracted and analyzed. SDS-polyacrylamide gel electrophoresis showed that a peptide with a molecular weight of about 24kDa was preferentially adsorbed onto the oil surface. This 24kDa peptide was found to be fairly hydrophobic and corresponds to the third domain of BSA, residues 377-582. In spite of the preferential adsorption characteristics of the 24kDa peptide, this peptide itself had a lower EAI value than that of the whole hydrolyzate. The contribution of some small hydrophilic peptides, as well as the 24kDa peptide, to the good emulsifying properties of the BSA hydrolyzate was suggested.