Electrospinning and heat treatment of whey protein nanofibers

The ability to develop nanofibers containing whey proteins presents a unique opportunity to exploit the inherent benefits of whey protein with that of the desirable attributes of nanofibers. In this study, aqueous whey protein solutions, both whey protein isolate (WPI) and one of its major components beta-lactoglobulin (BLG), are electrospun into nanofibers in conjunction with a spinnable polymer, poly(ethylene oxide) (PEO). WP:PEO solution composition as high as 3:1 and with average fiber diameters ranging from 312 to 690 nm are produced depending on polymer composition and concentration. WP/PEO solutions are also successfully electrospun at acidic pH (2 ≤ pH ≤ 3), which could improve shelf life. FTIR analysis of WP/PEO fiber mat indicates some variation in WP secondary structure with varying WPI concentration (as WPI increases, % α-helix increases and β-turn decreases) and pH (as pH decreases from neutral (7.5) to acidic (2), % β-sheet decreases and α-helix increases). XPS also confirms the presence of WP on the surface of the blend fibers, augmenting the FTIR analysis. Interestingly, WP/PEO composite nanofibers maintain its fibrous morphology at temperatures as high as 100 °C, above the 60 °C PEO melting point. In addition, the mats swell in water and retain a fibrous quality which makes them desirable for application in regenerative medicine. Finally, we incorporate a small hydrophobic molecule Rhodamine B (RhB) as a model flavonoid into WP/PEO nanofiber mats. The BLG:PEO nanofibers qualitatively exhibit improved fiber quality and RhB distribution compared to PEO nanofibers; however, no effect on the release profile is observed.