In situ synthesis of HKUST-1 on copper-ammonia fiber for preparation of quaternary-ammonium chitosan based active packaging with sustained-release cinnamaldehyde

Cinnamaldehyde (CIN) is gaining interest as a highly effective natural antimicrobial agent to extend the shelf life of fruits. However, its inherent instability limits further applications. In this work, a new strategy for the synthesis of HKUST-1 to encapsulate CINs by in situ growth method using copper-ammonia fiber as precursors is proposed. Subsequently, combining it with chitosan quaternary ammonium salt (CQAS) to formulate chitosan quaternary ammonium salt/copper-ammonia fiber@HKUST-1/cinnamaldehyde (CCAHC) packaging film. Based on copper-ammonia fiber to prepared HKUST-1, on the one hand, it has excellent compatibility with CQAS and improves the mechanical properties of the film. On the other hand, its porous structure also encapsulates CIN and significantly improves the stability of CIN (203h). Benefiting from the sustained release of CIN and Cu2+ from HKUST-1, CCAHC film not only exhibited long-lasting antimicrobial activity (12 days, 95 %), which was effective in prolonging the shelf life of strawberries, but also excellent antioxidant properties (20 h, 84 %), which maintained the good appearance of fresh-cut apples (over 14 h). Moreover, CCAHC films exhibited the great degradability in the soli, which promised it becoming a green packaging material. Therefore, this work provides an innovative method for designing CIN encapsulation and preparing bioactive packaging films.