Interfacial and emulsion properties of albumin-rich fractions from sunflower seeds

The interfacial and emulsion properties of mixed albumin-rich fractions extracted from sunflower seeds at pH 3 and pH 5 were analyzed. SDS-PAGE under reducing and non-reducing conditions was used to visualize differences between the protein fractions. The interfacial activity of the albumin-rich fractions was analyzed via drop contour measurement. The viscoelasticity of the protein film the interactions between the protein molecules, and the network forming within the protein film were measured by interfacial shear rheology. Besides being both surface active, albumin-rich fractions extracted at pH 5 were found to form interfacial films that exhibited a greater stability against deformation. In consequence, emulsions prepared with pH 5 extracts showed better properties represented by a smaller oil droplet size and a lower creaming index. The results proof that mixed albumin-rich fractions can stabilize emulsions. Moreover, the presence of co-extracted phenolic compounds seems to be important to generate systems with increased elastic properties of the interfacial film.