Desenvolvimento de um filme com propriedades ativas à base de fécula de araruta e extrato etanólico de própolis verde

Starch films are biodegradable bioplastics and may contain bioactive compounds – usually phenolic, from natural extracts - which are responsible for conferring properties such as antioxidant and antimicrobial activities. The development of this work has had the objective to obtain films with active properties based on starch of arrowroot added with ethanolic extract of green propolis. The films prepared by Solution Casting were evaluated according to the concentration of extract (3%, 10% and 20%, m/m of arrowroot) and encoded, respectively, FA3% EP, FA10% EP and FA20% EP. The film that did not contain extract, FA, was used as reference. The films were characterized by their physical, thermal, mechanical and optical features, their water solubility, water vapour permeability (PVA) and antioxidant and antimicrobial activity determination. The formulation of the films, which was done based on the results of the antioxidant and antimicrobial activities, was taken to a later stage in order to evaluate the effect of gamma radiation (5-50 kGy). According to the results obtained in the first stage, the concentration of propolis extract affected the chemical composition and properties of arrowroot films. The plasticizing effect of the propolis extract was confirmed by the reduction of the residual crystallinity and the modulus of elasticity in arrowroot films added by 20% of extract. The percentage of flavonoids and phenolic totals shown by arrowroot films were proportional to the extract concentration. These compounds reduced the solubility in water of the films added with propolis extract, however, they kept the PVA unchanged. In addition, the presence of flavonoids and phenolics in the films of arrowroot added with 10% and 20% of extract, gave them antioxidant and antimicrobial activity against Staphylococcus aureus and the formulation with a 10% extract was selected and submitted to gamma radiation. As for the results of the second stage, they demonstrated the effect of gamma radiation on the properties of arrowroot films by reducing the intrinsic viscosity and the average viscosimetric molecular masses for the FA and FA10% EP films. However, FA10% EP films, irradiated at the dosage 5 kGy, showed minimized changes. Regardless of the composition of arrowroot films, gamma radiation made them more amorphous, less resistant to traction, with a less rigid and more flexible structure, except FA10% EP films irradiated at a dosage 25 kGy. The FA10% EP films irradiated were more thermally stable, so that this stability was thought to be due to the presence of the propolis extract in the polymer matrix. It was also observed that the gamma radiation caused yellowing in the FA films and fading in the FA10% EP films. Finally, the bioactivity and radiolytic protection of arrowroot films added with propolis extract were thought to happen because of flavonoids and phenolic compounds. In this sense, the arrowroot films added with propolis extract can be applied in the development of bioactive packages and sterilized by gamma radiation.