Produção e caracterização de filmes ativos de TPS/PBAT adicionados de curcumina por extrusão reativa

Abstract

Active films or packaging are materials that interact with the food product detaining possible reactions related to the deterioration or alteration of sensorial or nutritional characteristics in the food, because they have in their formulation antioxidant or antimicrobial compounds. Biodegradable materials have been very explored for production of packaging by extrusion and blow, for example blends of thermoplastic starch (TPS) and poly (butylene adipate-co-terephthalate) (PBAT), which however do not present adequate miscibility. To bypass such fact, citric acid has been used to the esterification of the starch and to increase the compatibility with PBAT. However, few studies are found in the literature evaluating the production of compound materials by PBAT/TPS for use as active packaging for food. Curcumin, obtained from the rhizomes of the Curcuma longa L. (popularly known earth tumeric) is a polyphenolic compound with high antioxidant activity, being its application in active packaging very interesting. Thereby, the present study had the objective to produce and to characterize biodegradable films of TPS/PBAT by reactive extrusion with citric acid, added to curcumin. To evaluate the effect of the addition of curcumin (0,5% and 0,75% with regard to total formulation). Analysis were performed to determine the antioxidant activity (total phenolics) of films, color (colorimeter), the microstructure (Scanning Electron Microscopy, MEV) the thermal properties (Differential Scanning Calorimetry, DSC), the interaction among the components (Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance, FTIR-ATR), mechanical properties (traction trial) as well as the hydrophilicity of films (solubility in water). The results demonstrate that curcumin even after being subjected to the conditions of shearing, high pressure and temperature in the extrusion, still presents high antioxidant activity. With the results of the mechanical properties, FTIR-ATR and solubility realized a lower effectiveness of the reaction of esterification of the starch by the citric acid, consequently a less starch crosslinking. Possibly such effect was due to the interference of curcumin in the action of the citric acid. This effect also was checked in the micrographs of surface of the films with curcumin, where the starch grains stayed visibly apparent result of the decrease of the reticulation.