A Konjac Glucomannan-Based Antibacterial Packaging Film with Humidity-Triggered Release of Cinnamaldehyde

To meet the challenge of microbial contamination of food, smart packaging materials with active controlled-release functions have become a research hotspot. In this study, a humidity-responsive antimicrobial composite film was constructed by introducing cinnamaldehyde@β-cyclodextrin inclusion complexes (CIN@β-CD ICs) into a konjac glucomannan/polyvinyl alcohol/lithium chloride (KGM/PVA/LiCl) matrix. Characterization results showed that the CIN@β-CD ICs formed a dense structure through hydrogen bonding, which enhanced the thermal stability, mechanical strength (tensile strength: 20.83 MPa) and surface hydrophilicity (water contact angle < 60°) of the film. The film acted as a humidity-triggered release system for CIN, enabling controlled antimicrobial delivery: at high humidity (98% RH), the film rapidly swelled and accelerated the release of CIN, with a cumulative release rate of 87.29% over 7 days, whereas the release slowed significantly at low humidity (43% RH). The antimicrobial activity of the released CIN was strongly influenced by ambient humidity, with the effect enhanced under high humidity conditions. It is noteworthy that the film containing 0.2% ICs exhibited the optimal antimicrobial performance among the formulations studied. This study elucidates a mechanism for humidity-triggered release through multicomponent synergism, which provides a feasible strategy for the design of environmentally friendly, smart packaging materials with high antimicrobial activity.