Green-manufactured, pH-responsive biodegradable polyester packaging film embedded with curcumin and aminated cellulose nanocrystals for tunable gas permeability and antioxidant release

The development of intelligent and responsive active packaging from biodegradable polymers offers a sustainable strategy for food preservation. In this study, pH-sensitive, breathable, and antioxidant-active films were fabricated via a solvent-free extrusion casting process using a matrix based on poly(butylene adipate-co-terephthalate) (PBAT), integrated with an assembly of aminated cellulose nanocrystals and curcumin (A-CNC@CUR). This green fabrication approach aligns with cleaner production principles by avoiding organic solvents, enabling continuous processing, and incorporating biodegradable and renewable components. The films showed pH-responsive release, with curcumin liberation enhanced under acidic/alkaline conditions and >96 % radical scavenging at 24 h. Gas permeability was also pH-responsive: water vapor increased by 27 % at pH 4 and 33 % at pH 9, CO₂ by 52 % and 31 %, and O₂ by 46 % and 23 %, respectively. A-CNC@CUR films exhibited ∼50 % higher CO₂/O₂ selectivity than CUR-only films under acidic conditions. Mechanical reinforcement was achieved by blending PBAT with poly(butylene succinate) (PBS) and A-CNC@CUR, showing a 125 % tensile strength increase over neat PBAT. Agaricus bisporus trials demonstrated effective browning inhibition and shelf-life extension by the A-CNC@CUR-incorporated PBAT-based active films. This work highlights a scalable, cost-effective, and multifunctional packaging strategy that integrates antioxidant activity, atmosphere regulation, and biodegradability, contributing to sustainable food systems and advancing intelligent materials for climate-resilient circular economy.