Changes in the Emulsifying and Foaming Properties of Proteins during Heat Denaturation

Abstract

Changes in the emulsifying and foaming properties of ovalbumin, 7S globulin, κ-casein, β-lactoglobulin and bovine serum albumin were followed during heat denaturation, and these surface properties were correlated with the corresponding surface hydrophobicity, in order to investigate the role of surface hydrophobicity in the surface properties of proteins. The surface hydrophobicity of ovalbumin, 7S globulin and κ-casein increased with heat denaturation, while that of β-lactoglobulin and bovine serum albumin decreased. The emulsifying activity and emulsion stability of proteins correlated linearly with surface hydrophobicity, although protein structure changed greatly during heat denaturation. On the other hand, the foaming power of proteins correlated curvilinearly with surface hydrophobicity during heat denaturation. No significant correlation was observed between the foam stability and the surface hydrophobicity of proteins.
On the basis of these results, the relationships between the surface properties and the structure of proteins are discussed.