Starch-based bio-elastomers functionalized with red beetroot natural antioxidant

Red beetroot (RB) powder was incorporated into starch-based bio-elastomers to obtain flexible biocomposites with tunable antioxidant properties. Starch granules within the bio-elastomers affected the release of the antioxidant molecule betanin in the RB powder. The bio-elastomers were hydrophobic and resisted dissolution in water, hence the release of betanin was due to diffusion rather than polymer matrix disintegration. Hydrophobicity was maintained even after water immersion. Released betanin demonstrated highly efficient antioxidant scavenging activity against 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH center dot) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(center dot+)). RB powder was also found to increase the Young's modulus of the bio-elastomers without compromising their elongation ability. Infrared spectral analysis indicated weak interactions through hydrogen bonding among starch granules, RB powder and PDMS polymer within the bio-elastomers. Hence, as a simple but intelligent biomaterial consisting of mainly edible starch and RB powder the present bioelastomers can be used in active packaging for a variety of pharmaceutical, medical, and food applications. (C) 2016 Elsevier Ltd. All rights reserved.