Characterization of Functional Properties of Biodegradable Films Based on Starches from Different Botanical Sources

Starch is the main biopolymer used to develop biodegradable films and coatings, mainly due to its availability in nature and low cost. Therefore, it is important to determine the properties of starch-based packaging materials, since the characteristics of each material may differ according to the botanical source. In this study, the functional properties of biodegradable films made from starch isolated from four botanical sources, corn, sorghum, potato, and achira are evaluated. The mechanical, water vapor barrier, morphological, thermal, and hydration properties are studied. Obtained films have a homogeneous appearance with no pores or cracks. The potato and achira films present some non-gelatinized granules on their surface, however, they are the ones that present the highest mechanical properties, where the non-gelatinized granules function as a reinforcing material for the polymer matrix. The red sorghum starch films present the best barrier for water vapor. The source of starch shows a significant effect on the tensile strength (TS) and percentage of elongation at breaking (%E). The solubility, swelling index, and water vapor adsorption capacity change significantly when comparing the four botanical sources, mainly because of the differences in the morphology of the resulting materials, amylose content and the size of the starch granule.