Biodegradable Pectin-Based Films with Ternary Natural Eutectic Solvents for Enhanced Mechanical, Antioxidant, and Antimicrobial Properties

The development of biodegradable, functional food packaging demands advancements in mechanical strength, barrier properties, and active functionalities. This work describes the incorporation of ternary natural eutectic solvents based on choline chloride combined with tannic, gallic, or citric acid into pectin-based films, aiming at active food packaging applications. Employing a casting method, films were formulated at 200 and 400 wt % NAES concentrations based on pectin, enabling comprehensive evaluation of their structural, physicochemical, and active properties. Eutectic solvent integration significantly bolstered the mechanical performance of the films, with tensile strength increasing from ∼0.75 to ∼2 MPa, reducing water vapor permeability from 2.25 to 0.75 × 10–11 g/Pa.s.m2 and enhancing UV-blocking capacity in the 200–350 nm range. Biodegradation assays confirmed ∼80% weight loss after 20 days in soil, underscoring the films’ environmental compatibility. Additionally, natural eutectic solvents endowed the films with robust antioxidant, antifungal, and antibacterial activities, effectively inhibiting E. coli and S. aureus growth, with inhibition zones exceeding 22.5 mm. Real-food assays provided practical validation. Semihard cheese coated with these materials showed a ∼50% microbial reduction compared to control films containing traditional plasticizers. Similarly, chia oil samples sealed with these materials exhibited a strong antioxidant effect, with hydroperoxide values dropping from ∼55 to 5 mequiv O2/kg oil and induction periods extending from 0.25 to ∼5.2 h after 25 days of storage at 40 °C. This study underscores the multifunctional potential of ternary natural eutectic solvents in food applications, enhancing pectin-based films while delivering antioxidant and antimicrobial properties.