pH-sensitive edible films from Aloe vera gel, chitosan, green-synthesized zinc oxide nanoparticles, and beetroot anthocyanins: Properties, functionality, and greenness evaluation

In response to the growing demand for sustainable and intelligent food packaging, this study developed edible pH-sensitive films using Aloe vera gel (A), chitosan (C), green-synthesized zinc oxide nanoparticles (N)), and beetroot anthocyanins (B) via the casting method (ACNB films). ZnO NPs were synthesized through an eco-friendly plant-mediated approach, offering advantages in cost, time, and energy efficiency over conventional methods. The films were characterized for color parameters, mechanical properties, solubility, moisture content, pH sensitivity, water vapor permeability (WVP), oxygen permeability, light barrier properties, antioxidant capacity (DPPH and ABTS), and antimicrobial activity against Staphylococcus aureus and Escherichia coli . The optimal formulation (ACNB7%) exhibited significantly improved tensile strength (51.38 ± 3.63 MPa), reduced WVP, strong antimicrobial inhibition zones (13.83 mm for S. aureus and 15.17 mm for E. coli ), and clear visible color changes from red (acidic pH) to brown/blue (alkaline pH). Antioxidant activity increased with higher anthocyanin content. Environmental sustainability was assessed using AGREEprep (score: 0.86) and AGREE (score: 0.88) tools, indicating a highly green preparation and analytical process. These findings suggest that ACNB films hold strong potential as multifunctional, biodegradable, and intelligent packaging materials for real-time food quality monitoring and extended shelf life.