Multifunctional PBAT/Curcumin Bioactive Composite Films with Colorimetric Properties for Packaging

The extensive use of common petroleum-based plastics in food packaging has raised serious environmental concerns, accelerating the search for biodegradable and functional alternatives. In this study, poly(butylene adipate-co-terephthalate)/curcumin (PBAT/Cur) bioactive composite films with colorimetric sensing properties were successfully prepared via solution casting. A systematic characterization was conducted on the structural, morphological, barrier, antioxidant, antibacterial, and colorimetric properties of the films. The optimal PBAT/Cur1% films exhibited potent antioxidant activity (DPPH scavenging up to 95.6%) and moderate antibacterial activity against E. coli and S. aureus. Additionally, curcumin incorporation not only increased the water contact angle of the PBAT/Cur1% films, indicating enhanced surface hydrophobicity, but also concurrently improved the barrier properties, as evidenced by a reduced water vapor permeability (WVP of 14.58 g·mm/m2·day·kPa) and a lower oxygen transmission rate (OTR of 7.533 × 10−3 cm3/m2·day·Pa) compared to the neat PBAT films. Notably, the films displayed a distinct and rapid color change from yellow to reddish-brown upon exposure to ammonia vapor, suggesting their promise for on-package visual freshness indication. These findings highlight PBAT/Cur composite films as a sustainable option for active and intelligent food packaging, with combined antioxidant, antibacterial, and colorimetric properties, making them promising for packaging protein-rich foods (e.g., meat and seafood).