Preparation and characterization of pea protein isolate-pullulan blend electrospun nanofiber films

The objective of this work was to fabricate and characterize food-grade pea protein isolate (PPI) and carbohydrate polymer pullulan (PUL) nanofiber films by using green electrospinning technology. The effect of the blend ratios on the PPI/PUL solution properties (e.g. viscosity, surface tension and electrical conductivity) and morphology of the resulting electrospun nanofibers was investigated. The presence of PUL in the blends resulted in decreased apparent viscosity (P < 0.05), stable surface tension (42.09-46.26 mN/m) (P < 0.05) and lower conductivity of the solutions (P < 0.05), which were due to a better chain entanglement and decrease in the polyelectrolyte protein character, respectively, both factors were needed for uniform nanofiber (around 203 nm) formation. Rheological evaluation indicated a pseudoplastic behavior for all formulations. The Fourier transform infrared spectral changes and XRD patterns indicated that the protein and polysaccharide were well tangled in nanofibers. The results of the differential scanning calorimetry (DSC) indicate that thermal stability of the electrospun nanofiber films were improved in comparison to pure PUL. Finally, in order to expand the application range of the electrospun nanofiber films in future, thermal crosslinking method was conducted and water contact angles (WCAs) of the thermal treated nanofiber films exhibited better hydrophobic properties compared to the un-crosslinking samples.