Effect of anthocyanin-natural deep eutectic solvent (lactic acid/fructose) on mechanical, thermal, barrier, and pH-sensitive properties of polyvinyl alcohol based edible films

The aim of the current research was to fabricate and characterize the anthocyanin- natural deep eutectic solvent (NADES) incorporated polyvinyl alcohol (PVOH) based edible pH-sensitive films. Further the effectiveness of anthocyanin-NADES on the functional, structural, mechanical, and barrier properties of PVOH films has been investigated. The interaction and diffraction pattern at 19.1° for PVOH and NADES has been confirmed from FT-IR and XRD spectroscopy. The EDX spectra indicate the absence of metal components confirming the safety of the films. Additionally, the incorporation of NADES reduces the glass transition temperature and young modulus of PVOH films, whereas water vapour permeability (WVP), elasticity, and water solubility has been increased. The optical properties confirm that films provide reduced transparency confirming the usability against light-sensitive food products. The morphology in presence of NADES provides irregular flecks structures. A significant change in film color was observed on applying various pH buffers indicating the pH-sensitive property. Based on the above discussion, NADES aided PVOH-based edible films are considered as a potential candidate to be used as edible pH indicators for evaluating food quality during storage life, where the specific indicator can be ingested along with food products.