Preparo e caracterização de filmes comestíveis de quitosana Preparation and characterization chitosan edible films

The objective of this study is to characterize three commercial samples of chitosan with low degree of acetylation, as well as the preparation and characterization of edible films from these samples, aiming the subsequent application of these films in fruit coatings. The samples were characterized by molar mass, degree of acetylation, elemental analysis, infrared spectroscopy and thermal analysis, while the film was characterized by thermal analysis, infrared spectroscopy, total solids and water vapor permeability. The commercial samples showed different molar masses, which ranged from 132 to 245 kDa, degrees of acetylation from 5.8 to 6.3% and presented an elemental analysis next to the formula C 6 H 11 O 4 N, for the repeating unit. The films produced had thicknesses from 3.7 to 6.8 μm, total solids from 2.0 to 6.3 g m -2 and water vapor permeability from 170.1 to 180.2 g day -1 m -2 . The chitosan films with a higher content of solids and a lower molar mass were less permeable to water vapor. Infrared and thermogravimetric analyses showed the same functional groups and similar decomposition curves, respectively, for the samples and for the films produced.