Effect of Solvent Polarity on the Emulsifying Properties of the Flexible Zein

In order to explore the effect of solvent polarity on the emulsification of the flexible zein, scanning electron microscope, dynamic light scattering instrument, circular dichroic spectrometer were used to determine the morphology, particle size distribution, surface hydrophobicity, structure properties and emulsion properties of the flexible zein in different solvent environments (60%、70%、80%、90%、92% (v/v) aqueous ethanol solutions). The results showed that the aggregation morphology of the flexible zein was affected by the solvent polarity, and the particle size of the flexible zein aggregation was inversely proportional to the solvent polarity. The higher solvent polarity was, the better emulsifying activity of the flexible zein aggregation was, but the lower emulsifying stability was. When the ethanol concentration increased from 60% to 92%, the emulsion stability increased from 67.97% to 86.47%, the particle size of the emulsions decreased from 355.60 nm to 251.00 nm, and the zeta potential of the emulsion decreased from −40 mV to −42.85 mV. In addition, the lower the solvent polarity, the greater the α-helix structure and surface hydrophobicity of flexible zein. Different aggregations were formed from the flexible zein in different polarity solvents due to its different α-helix structure and surface hydrophobicity, and different emulsification properties were found from them. The results of this study provide a theoretical basis for broadening the application range of zein.