Fabrication of active and intelligent bio-based edible films using encapsulated beetroot powders for smart packaging

Abstract

To address food waste and promote sustainable food packaging, pH-sensitive edible films were developed using Opuntia ficus-indica mucilage (OM) and cellulose nanofibers (CNFs) incorporated with varying concentrations of the encapsulated beetroot waste extract (EB) (0.5%, 1%, 1.5%, and 2%). Based on the percentages of EB, the films were labelled as OM/CNF/EB (2%), OM/CNF/EB (1.5%), OM/CNF/EB (1%), OM/CNF/EB (0.5%), and OM/CNF (control). The films were prepared using the solvent casting method, and the impact of EB on the films’ mechanical properties, physical characteristics, and pH sensitivity was subsequently evaluated. The physicochemical properties of the film were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy to confirm the successful integration of EB into the OM polymer matrix. Furthermore, the incorporation of EB at varying concentrations significantly enhanced the film properties, including moisture content (28.20–57.77%), water solubility (11.52–56.15%), swelling test (80.12–83.18%), antioxidant activity (14.33–21.53%) and water vapor permeability (0.39–0.89 g m⁻¹ s⁻¹ Pa⁻¹). The films exhibited pH-sensitive color changes, transitioning from red to yellow within a pH range of 1 to 13, making them suitable for intelligent packaging applications. Notably, the 2% EB film effectively monitored the freshness of hake medallions, with a distinct color change correlating with spoilage indicators by day 4. These findings underscore the potential of OM/EB films for enhancing postharvest preservation.