Understanding the relationship between rheological characteristics of pulsed electric fields treated chitosan-zein-poly(vinyl alcohol)-polyethylene glycol composite dispersions and the structure-function of their resulting thin-films

Abstract

For the first time, this article elucidates how the rheological behavior of pulsed electric fields (PEF) treated chitosan-zein-poly (vinyl alcohol)-polyethylene glycol composite affects the physicochemical properties of the resulting biodegradable films. The dispersion was subjected to varying specific energy (QP) (60–400 kJ/kg) or electric field strength (EP) (0.8–3.4 kV/cm) before being developed into biodegradable films. Increasing the intensity of both QP and EP modified the dispersions' consistency, which became dominated by high-density molecular entanglements, leading to higher viscosity, Z-average diameter, and polydispersity index. The attenuated total reflectance-Fourier transform infrared spectroscopy results confirmed that PEF-treatment promoted extended chain conformation and exposed multiple reactive sites that facilitated intermolecular entanglements and bioconjugation between the biopolymers. Exposing the dispersions to QP > 160 kJ/kg (delivered at 3.4 kV/cm) or EP of 0.8–3.4 kV/cm (QP 585–633 kJ/kg) resulted in higher thermal stability as observed using TGA. Microstructural properties examined by X-ray diffraction and scanning electron microscopy showed clear interaction between the biomacromolecules at PEF intensities of QP 150–400 kJ/kg and EP 1.6–3.4 kV/cm through complex coacervation. These interactions resulted in regular, compact, and crystalline formations of the cast films. Nevertheless, films with high stability in a wet environment can be developed by subjecting the dispersions to QP of ~60 kJ/kg and EP of 0.8 kV/cm. The findings demonstrated how the combined mechanisms of PEF-induced microstructural modification of composite colloidal dispersions and protein-polysaccharide phase separation could be used to tailor biodegradable films.