The role of green technologies in producing wheat gluten nanofibers by electrospinning and improving their water resistance

Electrospinning of irregular proteins is possible if they can be dissolved appropriately and their spherical structure can be changed to a random coil, which is generally not the case for plant proteins. Thus, the effect of each solvent, including acetic acid (AA), ethanol (ET), and water (WA) alone, as well as their binary mixtures at 70:30, 50:50, and 30:70 (v/v) ratios on the nanofibers (NFs) obtained from treated gluten was investigated. Where the binary solvent systems of AA: ET and ET: WA (70:30 ratios) were selected, the average NFs diameters were 482.22 and 312.74 nm, respectively. Next, the effects of 3 factors, including solvent type, high hydrostatic pressure/HHP (0, 400, and 600 MPa), and dithiothreitol (DTT) (0 and 1 % of the protein weight) on gluten NFs were studied. Applying HHP and DTT effectively altered the protein conformation from beta-sheets to random coils. Considering fiber morphology (no beads and uniformity of fiber morphology) and production conditions, the sample treated at 400 MPa containing DTT was selected for gluten electrospinning in the AA: ET (70:30 v/v) solvent system. Finally, the effects of sandwiching (layers of zein protein), thermal, cross-linking with oxidized sucrose, and plasma methods on increasing the hydrophobicity of fibers were investigated. The dissolution time of different treatments, including sandwich NFs, thermal, and plasma methods, was 11.77, 35, and 1.19-4.64 s, respectively; the thermal method was proposed as the best modification method.