Cinnamaldehyde-enhanced starch/chitosan composite films: A promising solution for eco-friendly food packaging and...

To address the critical challenges of dissolution in humid environments and mechanical deterioration in starch-based films, this study developed a high-performance biodegradable composite packaging material by incorporating cinnamaldehyde and chitosan into the starch matrix. Unlike existing systems requiring synthetic modifiers such as NIPA and AKD, this work constructed a more concise, fully bio-based ST-CIN/CS ternary composite system, effectively overcoming issues of swelling and poor mechanical properties in starch-based films. Physicochemical analyses confirmed that a unique molecular network formed among starch (ST), cinnamaldehyde (CIN), and chitosan (CS) through hydrogen bonding and hydrophobic interactions, endowing the film with high transparency and significant hydrophobicity. This successfully resolves the typical trade-off between barrier performance and light transmittance in bio-based packaging materials. The ST-CIN/CS composite film demonstrated a water contact angle of 82.50°, a reduced water vapor transmission rate of 0.20 g/m²/day, and ultralow UV transmittance of 0.27 % at 350 nm. The incorporation of CIN and CS significantly enhanced the film's antimicrobial and antioxidant activities. Furthermore, the ST-CIN/CS film effectively extended fruit shelf life by regulating respiratory metabolism, inhibiting lipid peroxidation, and suppressing microbial growth, demonstrating a multi-mechanism preservation effect.