Surface Morphology of Chitosan Films with Incorporation of Grape Pomace Cláudia Nunes 1 , Alichandra Castro 2 , Andreia S. Ferreira 1 , Paula Ferreira 2 and Manuel A. Coimbra 1 1. QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal 2. CICECO, Departamento de Engenharia de Materiais e Cerâmica, 3810-193 Aveiro, Portugal The use of edible films and coatings in food protection and preservation from renewable biopolymers has recently increased due to its nontoxicity, biocompatibility, and antimicrobial properties. Further, edible films can be an efficient vehicle for incorporating functional compounds, which improve its characteristics [1]. Grape pomace consisting of skins, seeds, and stems, is a rich source of phenolic compounds, lipids, polysaccharides and proteins. Since grape pomace is an abundant by-product, there is a high interest to use its extracts in order to improve the chitosan films properties. This work consists in the preparation of chitosan-based films with improved properties for food applications. Three grape pomace fractions are incorporated: 1) hot water extract (HWE), with 72 % polysaccharides; 2) chloroform extract, rich in waxes (W); and 3) n-hexane extract, with the oil (Oil), comprising 70 % linoleic acid. As control, a film only with chitosan (Ch) is also prepared. The study of the films morphology, mainly with incorporation of natural extracts, is important since there is a direct correlation between morphological properties and mechanical and permeability behaviour of the films [2]. Then, tapping mode Atomic Force Microscopy (AFM) is used to observe the surface characteristics of the films with grape pomace fractions incorporation and control. The chitosan-based films are homogenous without cracks or macropores by a macroscopic point of view. However, using AFM, it is possible to verify that all films presented roughness (Figure 1). The Ch film shows a good structural integrity with a hill-valley-structure that is regular and homogeneously distributed on the surface due to the distribution of uncross-linked chitosan-fibres [3]. The height profiles showed that the chitosan films had a maximum vertical distance of 7.14 ± 0.58 nm and a roughness medium square of 1.98 nm. The HWE films show a more homogenous surface (roughness medium square = 0.76 nm) than chitosan film. These films also present the hills and valleys structure, but the maximum height was 2.63 ± 0.32 nm, more than 2.5 times lower than the control films. However, the fibre diameter is higher than in Ch film (0.51 ± 0.12 μm), probably due to the formation of a network between the polysaccharides of the aqueous extract with the chitosan matrix, which also confer low roughness to the surface. The films with incorporation of wax have flat areas combined with large aggregates and deflection regions, leading to a roughness medium square of 6.03 nm, which is nearly 3 times higher than Ch film and ca. 8 times higher than the HWE film. These irregularities (maximum height of 15.24 ± 4.40 nm) suggest that the wax was not well dispersed in the chitosan film forming solution, probably due to the high molecular weight and hydrophobic character. The presence of the fibre is less evident in the film surface when compared with the previous films. The addition of the grape seed oil to the chitosan forming solution originated a film with a maximum peak height of 4.51 ± 1.29 nm and roughness medium square of 2.42 nm. The decrease of the peak height when compared with the Ch film, may indicate the existence of some weak interactions between chitosan and triacylglycerides, such as hydrogen bonds. The oil film also shows some deflections with a regular distribution in the film surface, but these irregularities are smaller than the ones observed in the film with wax. The results obtained with AFM analysis reveal that the chitosan films morphology depends of the incorporated extract. The chitosan film with the incorporation of the aqueous extract showed a more homogeneous and smoother surface compared with the other films. The incorporated compounds tend to Microsc. Microanal. 21 (Suppl 5), 2015 © Microscopy Society of America 2015 35 doi:10.1017/S1431927615013987