Starch is the most important polysaccharide polymer used to develop biodegradable films, mainly used for packaging applications. Due to high hydrophilicity and poor mechanical properties of biodegradable starch film, different types of natural carboxylic acids were introduced into cassava starch film. These were lactic acid (LA), malic acid (MA) or citric acid (CA), classified as the mono-, di- and tri-carboxylic acid, respectively. It was found from Infrared ( IR) spectra that new IR peak position arisen from the ester group and new hydrogen bond formation were observed for different acid-modified starch films. In addition, the incorporation of different types of the acids into the cassava starch film also caused significant decrease of swelling, water uptake and water vapor permeability (WVP) because of more hydrophobicity of various starch films modified by the acids. Comparison among different types and contents of the acids used for modifying cassava starch films was performed. Furthermore, morphological, thermal and biodegradable properties were also investigated.
