title: Influence of grape pomace extract incorporation on chitosan films properties.
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.
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Andreia S
authors.initials: AS
authors.lastname: Ferreira
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal. Electronic address: claudianunes@ua.pt.
authors.forename: Cláudia
authors.initials: C
authors.lastname: Nunes
authors.affiliation: CICECO, Departamento de Engenharia de Materiais e Cerâmica, 3810-193 Aveiro, Portugal.
authors.forename: Alichandra
authors.initials: A
authors.lastname: Castro
authors.affiliation: CICECO, Departamento de Engenharia de Materiais e Cerâmica, 3810-193 Aveiro, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Ferreira
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Coimbra
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry*; D006586:Hexanes / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry*; D027843:Vitis / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D006586:Hexanes; D010936:Plant Extracts; C026385:n-hexane; D048271:Chitosan
keywords: Antioxidant activity; Atomic force microscopy; Edible films; Mechanical properties; Solubility