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Biocompatible materials with high dielectric constant and low dielectric loss have applications in bio-related electronic devices. Development of flexible materials with those properties is still a challenge. In this work, electrospun membranes and films are prepared from poly(vinyl alcohol) (PVA) and chitosan (CS) solutions, incorporated with a reduced graphene oxide-zinc oxide composite (rGO-ZnO). Blending CS with flexible PVA favors electrospinnability and mechanical properties. ZnO contributes to hinder agglomeration of conductive rGO sheets. The structural, mechanical, dielectric and electrical properties of the hybrid materials are investigated. Infrared spectroscopy reveals interaction between the filler and the polymeric components.For mats and films, the increase in rGO-ZnO content leads to lower crystallinity. The Young's modulus and stress at break values increase with increasing rGO-ZnO content. High dielectric constants (ε' = 132 to ε' = 166, at 10 3 Hz), associated with low dielectric loss factor (tan δ = 0.02), are determined for the PVA/CS/rGO-ZnO films.

Umbu is a native fruit of the semi-arid Northeastern region of Brazil, which presents an exotic and differentiated flavor. Containing vitamin C and presenting a high potential of consumption, no appropriated technology has been developed to process this fruit and expand its commercialization to other markets. The enzymatic treatment of fruit pulps leads to viscosity reduction, which makes possible an efficient processing for obtaining high quality umbu juices. In order to contribute to the valorization of this underexploited culture, two commercial pectinolytic enzymes, Pectinex Ultra SP-L and Rapidase TF, were used to promote viscosity reduction of umbu pulp. The effect of reaction temperature (35, 45 and 55 °C) and enzyme concentration (100, 200 and 300 ppm) on the rheological properties of the fruit pulp was evaluated. In relation to the viscosity of the original pulp (84.8 mPa s at 100 s shear rate), a significant, four times lower, viscosity reduction of 18.9 mPa s was observed. Under optimum process condition (35 °C and Rapidase at 100 ppm concentration), the lowest viscosity was achieved after 40 min of reaction. Under these reaction conditions, no significant change was found in the vitamin C content, indicating the preservation of functional and nutritional properties of umbu pulp.

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