Protease-Mediated Synthesis of Zein Nanofibrils: From Structural Elucidation to Functional Application

The fibrillization of plant-based proteins enhances their functionality, enabling potential applications in food and sustainable materials. Zein, a highly hydrophobic protein from corn, is a versatile industrial ingredient, but its functionality is limited to environments containing high levels of organic solvents. This study aims to develop a protease-assisted approach for synthesizing zein nanofibrils as functional building blocks, eliminating the need for organic solvents in the conventional process. Through proteomics, microscopy, and spectroscopy, the bioprocess and structural features of these novel nanofibrils are characterized. The results reveal that over 50% of α-zein sequence is prone to fibrillization, with pepsin demonstrating a clear advantage in efficiently releasing fibrillization-prone peptide segments (bioconversion > 70%) and producing a peptide mixture suitable for self-assembly. The fibrillization process is significantly enhanced by increasing peptide concentration and adding the anionic surfactant sodium dodecyl sulfate, which can lead to the formation of semiflexible fibrils with amyloid-like β-sheet structures. These nanofibrils outperformed native zein as emulsifiers in high internal phase emulsions and are able to form fibrous hydrogels. The protease-assisted fibrillization process achieved in this study provides an effective solution for expanding applications of zein or corn proteins in a purely aqueous environment.