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

Key words: phosvitin, emulsifying activity, protease digestion, hen egg yolk