Schiff base cross-linked dialdehyde β-cyclodextrin/gelatin-carrageenan active packaging film for the application of carvacrol on ready-to-eat foods

The construction of films has often been devoted to loading active substances to improve biological activity in recent years. However, the positive impacts on packaging properties by establishing a cross-linking reaction between the load materials and the substrate are frequently overlooked. The essence of this work was to cross-linked gelatin-based film with κ-carrageenan and dialdehyde β-cyclodextrin inclusion (IC/DA-β-CD) and the functionalities were also investigated. β-cyclodextrin was oxidized with sodium periodate to introduce aldehyde groups. The hydrophobic cavity was not disrupted and the modified cyclodextrin exhibited solubilization of carvacrol. In addition, the introduction of aldehyde group improved the dispersion effect of cyclodextrin in water, but the solid particles were more likely to gather when exposed to the air. Electrostatic complexation of gelatin and κ-carrageenan significantly (p < 0.05) enhanced the tensile strength (from 10.85 to 26.54 MPa), surface water contact angle (WCA) from 97.16 to 110.08° and thermal stability of the film. Contrarily, the elongation at break rate decreased significantly and the antibacterial activity was not potent. The crosslinked IC/DA-β-CD further improved the mechanical properties, and excellent barrier capabilities of the film. Consequently, the WCA and thermal stability were further enhanced as well as the antioxidant capacity and antibacterial activity against Listeria monocytogenes (the eradication rate reached 99.989%). Release experiments demonstrated cross-linked film was more suitable for fatty foods with excellent packaging application ability for ready-to-eat (RTE) ham. Based on the promising properties, the cross-linked film has great deal of potential as RTE active packaging.