Films based on mixtures of zein, chitosan, and PVA: Development with perspectives for food packaging application

Abstract

This work aims at the production and characterization of promissory food packaging films based on chitosan (CS), zein (ZN), and poly (vinyl alcohol) (PVA). CS and ZN are biodegradable, biocompatible, and extracting from natural-sources and renewable. Although PVA is a synthetic polymer, it is also considered biocompatible and present water-solubility. From binary and ternary macromolecule mixtures based on CS/ZN/PVA, were obtained films solvent-free. In this facet, extrusion of the macromolecule mixture following by a hot compression to acquire the films' solvent-free. The films were characterized by several techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), prioritization query based on critical packaging requirements which underwent visual and sensorial (smell), mechanical properties, scanning electron microscopy (SEM), and barrier property analysis. Our findings showed that a higher proportion of ZN led to yellowish films with lower transparency and/or higher opacity. Therefore, PVA high content is interesting for our proposal since it allows films with translucency, handling, absence of rupture, and odor. The mechanical tests showed that the ZN effect is associated with reduced tensile strength, increasing elongation, and Young's modulus. Thus, ZN's presence, even if in a smaller proportion to PVA, allows the formation of more rigid films. The morphological analysis indicates the formation of compact films and homogeneous surfaces. However, films with higher amounts of CS and ZN presented greater roughness, globular clusters' presence, and heterogeneity (films' cross-section) that may have influenced water vapor permeability values and better barrier property due to tortuosity that decreases as the PVA content is increased. This finding can be associated with the higher crystallinity of the film when the film's formulation presents significant CS and ZN concentrations. Finally, we demonstrate the feasibility of using films based on the mixture of CS, ZN, and PVA as proposals for a food pack.