Desenvolvimento de filmes biodegradáveis para embalagens de alimentícias obtidos da mistura de zeína, quitosana e poli (Álcool vinílico)

Abstract

The present work aims at the production and characterization of biodegradable zein (ZN) food packaging films. Zein (ZN) is a natural, biocompatible and biodegradable polymer. However, if used in food packaging it presents some weaknesses. Thus, the incorporation of other materials to ZN is an interesting strategy to overcome these limitations, aiming at applications of ZN-based films in food packaging. Chitosan (CS) is a natural, biodegradable polymer with good filmogenic capacity and can facilitate the production process of food packaging films. In common, both materials, ZN and CS, have low mechanical strength. Poly(vinyl alcohol) (PVOH), a synthetic and biodegradable polymer, has attractive properties not found in ZN and CS, such as high mechanical strength. From an experimental design, ternary polymeric mixtures (ZN / CS / PVOH) were prepared by the extrusion method and the respective films were prepared by compression. The samples were characterized from a prioritization queries, based on critical packaging requirements, which were qualitative properties, mechanical properties and barrier properties. In the qualitative properties, visual analysis and sensory analysis (smell), it was observed that the presence of PVOH in greater proportion is interesting because it gave the films greater transparency, handling and absence of rupture and odorless. Higher percentages of ZN led to yellowish films with lower transparency and, consequently, to higher degree of opacity. The the mechanical tests showed that higher ZN contents are associated with lower tensile strength of the films and increase in both elongation and Young's modulus. Thus, the presence of ZN even in smaller proportion related to PVOH allows the formation of more rigid films. Morphological analysis indicate the formation of films with compact and homogeneous structures. However, films with higher amounts of ZN and CS had higher roughness and presence of globular clusters that may have influenced water vapor permeability values and better barrier property due to tortuosity. Finally, the feasibility of using ZN, CS and PVOH for film preparation for use in food packaging was demonstrated in this dissertation.