A poluição do meio ambiente devido ao descarte de filmes plásticos de polímeros sintéticos sem nenhum controle é um grande problema mundial. Para minimizar este problema, existe a possibilidade da utilização de biofilmes, e o amido é um dos materiais que pode participar da elaboração desse material, sendo biodegradável quando lançado no meio ambiente.Biofilme é um filme fino preparado a partir de materiais biológicos, que age como barreira a elementos externos e, conseqüentemente, pode proteger o produto embalado de danos físicos e biológicos e aumentar a sua vida útil.Recentemente tem havido um grande interesse pelo desenvolvimento de biofilmes comestíveis ou degradáveis biolo- AbstractCassava starches may be used as raw materials for developing biodegradable films. Some starch modification processes can make them miscible in cold water and others can modify their film properties, making them stronger and more flexible. The aim of this study was to evaluate the physical characteristics of biodegradable films developed from cassava modified starches using the casting process (dehydration of a filmogenic solution on Petri dishes). The modified starches used were cross linked, low and high viscosity carboxymethyl starches and esterified starch. Starch viscosity is an important property to produce the filmogenic solution and it was tested using the Rapid Visco Analyser (RVA). Excepting cross linked starch, all modified starches presented cold solubility. This property enables an easier preparation of the filmogenic solutions. However, all modified starches presented a severe reduction of setback values, property associated with film formation. The cassava modified starch films were compared to commercial PVC films of 0.0208 to 0.0217 mm thickness. The cassava modified starch films presented thickness values from 0.0551 to 0.1279 mm. The minimum thickness values were observed in pre-gelatinized and cross linked films. The scanning electron microscopy analysis of the films showed differences among the starches. The resulting films were transparent and homogeneous. There was no significant interference of film thickness in water vapor permeability and the films with 5% dry matter were more permeable than the PVC film. However, when modified starch films are compared to PVC commercial films, there is still much research to be made in the formulation to improve several properties necessary to fulfill the requirements of food packaging today. Keywords: cassava; modified starch; film; viscosity. ResumoAmidos de mandioca podem ser matérias-primas para a obtenção de filmes biodegradáveis, sendo que para a formação destes é necessária a elaboração de suspensões filmogênicas. Alguns processos de modificação do amido podem torná-lo miscível em água fria, e outros processos de modificação podem alterar as propriedades dos filmes, tornando-os mais fortes e flexíveis. O objetivo deste trabalho foi verificar as características físicas de filmes biodegradáveis elaborados com amidos modificados de mandioca pelo processo de casting (...

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Cassava starches are widely used in the production of biodegradable films, but their resistance to humidity migration is very low. In this work, commercial cassava starch films were studied and classified according to their physicochemical properties. A nondestructive method for water vapor permeability determination, which combines with infrared spectroscopy and multivariate calibration, is also presented. The following commercial cassava starches were studied: pregelatinized (amidomax 3550), carboxymethylated starch (CMA) of low and high viscosities, and esterified starches. To make the films, 2 different starch concentrations were evaluated, consisting of water suspensions with 3% and 5% starch. The filmogenic solutions were dried and characterized for their thickness, grammage, water vapor permeability, water activity, tensile strength (deformation force), water solubility, and puncture strength (deformation). The minimum thicknesses were 0.5 to 0.6 mm in pregelatinized starch films. The results were treated by means of the following chemometric methods: principal component analysis (PCA) and partial least squares (PLS) regression. PCA analysis on the physicochemical properties of the films showed that the differences in concentration of the dried material (3% and 5% starch) and also in the type of starch modification were mainly related to the following properties: permeability, solubility, and thickness. IR spectra collected in the region of 4000 to 600 cm(-1) were used to build a PLS model with good predictive power for water vapor permeability determination, with mean relative errors of 10.0% for cross-validation and 7.8% for the prediction set.

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