Propolis is a natural product that meets the requirements as functional additive for food packaging due to its antioxidant and antimicrobial activities. In this work, ethanolic propolis extract (EPE) was incorporated in cassava starch films, and characterisations with respect to their microstructure, mechanical properties, water vapour permeability (WVP), moisture sorption kinetics as well as antimicrobial and antioxidant capacities were performed. The results showed that tensile strength was not affected (P > 0.05) by the presence of EPE but Young's modulus decreased about 50% when compared to control films possibly because of EPE plasticiser effect. When 1% EPE was used, changes in moisture sorption properties were detected by a slightly hydrophobic character at films WVP. When extracted from the films, propolis retained its antioxidant activity. The films exhibited antimicrobial activity against Staphylococcus aureus and Escherichia coli even at low EPE concentrations (0.5%) mainly due to its phenolic compounds.

In the present work, poly (lactic acid)/thermoplastic starch/gelatin sheets were produced by calendering–extrusion process and silver nanoparticles (AgNPs, synthesized by chemical reduction with d‐glucose), were incorporated at sheet surfaces to promote antimicrobial activity. A gelatin solution containing AgNPs was enzymatically crosslinked as a layer at sheets surface using transglutaminase. AgNPs presented 63 nm (z average size) and spherical shape (scanning electron microscopy, SEM) while morphology analysis showed that sheets presented internal porosity. Mechanical properties (Young modulus, elongation at break, and tensile strength) and water vapor permeability presented significant difference in function of gelatin amount added to sheets formulation due to increased internal porosity. Antimicrobial activity was demonstrated against Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa for the AGNPs solution as well as for the surface treated films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43039.

Este trabalho teve como objetivo produzir laminados a partir de blendas de amido termoplástico e poli(ácido lático) (PLA) adicionados de citrato de tributila (TBC) e ácido cítrico por extrusão plana (calandragem). A adição de TBC e ácido cítrico reduziu a rigidez dos materiais e elevou a permeabilidade ao vapor de água (PVA) e a densidade. Isso ocorreu porque, provavelmente, estes compostos atuaram como plastificante para o PLA e amido. Com isso, concluiu-se que foi possível a produção de laminados de amido e PLA pelo processo de extrusão, mas estudos ainda são necessários para encontrar a concentração adequada de TBC e ácido cítrico que não comprometam de forma significativa as propriedades de barreira ao vapor de água.

<p>The use of blends containing biodegradable polymers like starch and poly (lactic acid) (PLA) has gained considerable attention, especially for the food packaging production. Current research has also highlighted the use of chitosan because their antimicrobial activity, biodegradability and applicability in the production of active biodegradable food packaging. The objective of this work was to produce cassava starch and PLA sheets incorporated with chitosan by flat extrusion process (calendering-extrusion), and evaluate the mechanical, water vapor barrier and microstructural properties. In order to simplify the obtainment of the material reducing processing steps, all components of the blend were homogenized in one step extrusion The incorporation of chitosan in the starch/PLA sheets decreased significantly the tensile strength, Young's modulus, elongation at break and density. In addition, the scanning electron microscopy images showed the formation of non-homogeneous mixtures with the presence of pores between the blend compounds, and this fact affected the water vapor barrier properties increasing water vapor permeability, solubility and diffusion coefficients. It was possible to conclude that although the incorporation of chitosan to the starch/PLA sheets has not contributed to obtain materials with suitable properties, it was able to produce them by calendering-extrusion process in pilot scale. Studies about chitosan incorporation in starch and PLA sheets still needed.</p><p>&nbsp;</p><p>DOI: 10.14685/rebrapa.v6i1.208</p><p>&nbsp;</p>