Produção e caracterização de filmes biodegradáveis de amido de batata (Solanum tuberosum L.) para aplicação em embalagens de alimentos

Abstract

The need for replace conventional plastics due to environmental preservation is increasing the production of biodegradable polymers. The use of starch accessible sources is under consideration for use in films and the modification provides improvement in mechanical and barrier properties of starch. This study aims the production and characterization of biodegradable films of potato Solanum tuberosum L (asterix variety) native and chemically modified starch. The potato starch was isolated and subjected to chemical modification by oxidation method exposed to sodium hypochlorite in 0.5% and 1.5% concentration of active chlorine. The film solution was prepared using starch and glycerol or sorbitol [0.20 and 0.30 gplasticizer /gstarch] using the casting technique. To evaluate the mechanical properties were performed tensile tests by Dynamic Mechanical Analysis technique (DMA). The barrier property evaluated was Water Vapor Permeability (WVP). The morphology was analyzed by optical microscopy (OP), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The structural properties were evaluated by X-ray Diffraction (XRD) and Fourier Transform Infrared (FT-IR). Also was evaluated thickness, color and solubility. For the tensile test, the elastic modulus ranged from 219 ± 14.97 MPa to 2299 ± 62.91 and the tensile strenght from 5.44 ± 0.42 MPa to 47.35 ± 4.04 Mpa. The PVA had lower values for the oxidized starch films plasticized with sorbitol at its highest content (0.5% S0,30 = 4.09 .10-12 ± 2.15 .10-12 g/m.s.Pa). As for morphology, the micrographs showed partially gelatinized starch granules and the AFM smooth surfaces for the films. For starches XRD pattern showed crystallinity of type B, which represents tubers, residual starch crystallinity was observed in the films. In FT-IR, the films showed similar bands in compare to raw material, differing in their intensity. The films with glycerol was the thinnest, about 0.05 ± 0.004 mm, and showed lower ΔΈ. The lowest value for the 0.5% sample G0,30 of 5.54 ± 0.008%. The oxidized starch films with less sorbitol content had lower solubility (0.5% S0,20 = 3.05 ± 0.36%). The oxidation resulted in improvements in starch properties and film as well as the use of sorbitol as a plasticizer once the better results for application were 0,5% S0,20, 0,5% S0,30, 1,5% S0,30 e 1,5% S0,20.