Facile Dissolution of Zein Using a Common Solvent Dimethyl Sulfoxide

The conformation and stability of zein in solution are closely associated with its solvation process and influence the mechanical properties of the related zein-based materials. In this work, a common solvent dimethyl sulfoxide (DMSO) was used to dissolve zein, rather than solvents frequently used such as aqueous ethanol and acetic acid. It was found that DMSO could dissolve zein readily and the solution was stable for at least 2 weeks. Rheological analysis and small-angle X-ray scattering (SAXS) were employed to characterize the zein DMSO solution. Results of rheological analysis suggested a Huggins coefficient of 0.24, indicating DMSO to be a good solvent for zein. SAXS results revealed that zein adopted an elongated conformation and had dimensions of 2.8 nm × 2.8 nm × 14.8 nm in DMSO solution. Moreover, robust zein films were fabricated from zein DMSO solutions. The content of residual DMSO in the films was determined to be approximately 15 wt % by thermogravimetric analysis, in consistence with the value obtained by other two methods. The film showed a large breaking strain of 320.6% with a considerable breaking stress of 1.9 MPa, yielding a breaking energy of 376.2 MJ/m³. Therefore, the ease of dissolution and good mechanical performance of the final zein-based material make DMSO a potential solvent for fabrication of zein materials, thereby improving the scope of practical applications of zein.