abstract
Chitosan has been studied as a renewable polymer to form edible films allowing the incorporation of functional compounds. The aim of this work was to evaluate the effects in the chitosan films properties of the incorporation of grape pomace extracts: 0.15% of hot water extract (mainly polysaccharides), 0.15 and 0.3% of chloroform extract (wax), and 0.3 and 0.75% of n-hexane extract (oil). The evaluation of the surface morphology revealed that the films with the aqueous extract had the most homogeneous and smoother topography. The incorporation of higher proportion of wax and oil led to changes in mechanical properties of the films, namely lower resistance and stiffness. The chitosan-based films with 0.75% oil demonstrated a 75% decrease of solubility in water, due to their hydrophobicity, as confirmed by the contact angle and surface free energy measurements. The hydrophobic films showed higher antioxidant capacity in organic medium (ABTS and DPPH assays) whereas the most hydrophilic films showed an improvement in FRAP and reducing power assays. Therefore, all the chitosan-based films prepared by incorporation of these grape pomace extracts are promising for food shelf life extension. (C) 2014 Elsevier Ltd. All rights reserved.
keywords
ANTIOXIDANT ACTIVITY; MOLECULAR-WEIGHT; ESSENTIAL OIL; PHYSICOCHEMICAL CHARACTERIZATION; ANTIMICROBIAL PROPERTIES; MECHANICAL-PROPERTIES; FOOD APPLICATIONS; COMPOSITE FILMS; SEED EXTRACT; FATTY-ACIDS
subject category
Chemistry; Polymer Science
authors
Ferreira, AS; Nunes, C; Castro, A; Ferreira, P; Coimbra, MA
our authors
Alichandra Maria Gonçalves Castro
PhD Student
Cláudia Nunes
Assistant Researcher
Paula Celeste da Silva Ferreira
Coordinating ResearcherGroups
G2 - Photonic, Electronic and Magnetic Materials
G4 - Renewable Materials and Circular Economy
acknowledgements
Thanks are due to Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), European Union, QREN, FEDER, and COMPETE for funding the QOPNA research unit (project PEst-C/QUI/UI0062/2013; FCOMP-01-0124-FEDER-037296), CICECO (Pest-C/CTM/LA0011/2013; FCOMP-01-0124-FEDER-037271), and FCT project (PTDC/AGR-ALI/101251/2008). C. Nunes, A. Castro and P. Ferreira thank FCT for the Post-Doctoral fellowship SFRH/BPD/46584/2008, Doctoral fellowship SFRH/BD/67121/2009, and research position IF/00327/2013, respectively. The authors also thank Dao Sul-Sociedade Vitivinicola S.A (Carregal do Sal, Portugal) for providing the grape pomace.