Incorporation of zein nanofibers produced by needle-less electrospinning within the casted gelatin film for improvement of its physical properties

Zein as a hydrophobic plant protein has high tendency to form nanofibers. In this research, needle-less electrospinning with rotating spiked-like spinneret was applied for pilot-scale production of zein nanofibers and then produced fibers were used for improvement of properties of gelatin edible films. The properties of zein solutions were analyzed to investigate their effects on features of nanofibers. With increasing of zein concentration and decreasing applied voltage, the diameters of the fibers raised. FTIR data revealed that the second structure of zein did not change during needle-less electrospinning. Thermal gravimetric analysis showed an important increase in thermal stability of zein nanofiber in comparison to the pure zein. The prepared nanofibers under optimum criteria (zein concentration of 13% (W/V) and voltage of 21 kV) had mean diameter of 334 +/- 139 nm and were used as scaffolds for gelatin film. With applying zein nanofiber in gelatin films, moisture content, water solubility, swelling percentage, vapor permeability, elongation at breaking point and transparency decreased while thickness, tensile strength and elastic modulus increased. An enhancement in hydrophobicity of gelatin films were observed with increasing of zein concentration in nanofiber. The results indicated that this novel needle-less electrospinning can be applied for large-scale production of nanofibers and enhancement of properties of gelatin films. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.