Enhanced performance and functionality of active edible films by incorporating tea polyphenols into thin calcium alginate hydrogels

Active edible films were prepared consisting of tea polyphenols incorporated within thin calcium alginate gels. These films were prepared by plating an alginate solution, air drying (50 °C), and then cross-linking with calcium. In this study, the effects of tea polyphenol incorporation (1–5% w/w) on the physicochemical, morphological, and antioxidant properties of the films were evaluated. The tensile strength, breaking strain, and water vapor permeability of the films increased as the tea polyphenol level increased, whereas the optical transmittance as measured by UV–visible spectrometer decreased. Fourier transform infrared spectroscopy indicated that various types of intermolecular interactions occurred between the alginate and tea polyphenols. Scanning electron microscopy showed that the films had smooth surfaces with dense internal structures. The antioxidant capacity of the films, as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiozoline-6)-sulphonic acid (ABTS) radical analysis, and the anti-inflammatory properties were enhanced by incorporating tea polyphenols into them. Overall, this study showed that the functional properties of active edible films can be enhanced by introducing tea polyphenols, which may lead to new applications of these films for food packaging applications.