Effect of Protease Digestion and Dephosphorylation on High Emulsifying Properties of Hen Egg Yolk Phosvitin

Abstract

The emulsifying properties, particularly the emulsion stability, of phosvitin was found to be higher than those of other food proteins. The emulsifying activity and emulsion stability were greatly decreased by protease and phosphatase treatment. The protease digestion of phosvitin resulted in the peptide cleavage of large fragment (a highly phosphorylated core region, 50 to 210 peptide) and small fragments (N-terminal 1 to 49 and C-terminal 211 to 217 peptides). The large fragment lacking the small fragments did not show the excellent emulsifying properties, suggesting that small fragments of protein moiety play an important role in emulsifying properties. On the other hand, the effect of phosphatase treatment showed that electrostatic repulsive force of phosphate in phosvitin has a significant affect on its emulsifying properties and that the protein moiety with abundant phosphorylated residues is also considered to be essential for the high emulsifying properties.