Preparation of gelatin/ĸ-carrageenan active films through procyanidins crosslinking: Physicochemical, structural, antioxidant and controlled release properties

Active film is an emerging technology for food preservation, which can effectively control the sustained release of antioxidant is an urgent problem. Herein, procyanidins were incorporated into gelatin films as a cross-linking agent and antioxidant to improve the physical and antioxidant properties of the gelatin films, and different amounts of ĸ-carrageenan were also added to increase the tortuosity of procyanidins diffusion paths (gelatin:ĸ-carrageenan (G:C) = 1:2, 1:1, and 2:1), resulting in a sustained release of procyanidins. The films were evaluated for their mechanical, barrier, morphological, antioxidant, and controlled release properties. The results showed that the incorporation of procyanidins improved the mechanical, moisture resistance and optical properties of the films. FTIR measurements and molecular docking confirmed the crosslinking reaction between procyanidin and gelatin/ĸ-carrageenan. XRD and SEM showed that these three compounds had good compatibility. Procyanidins could improve the antioxidant activity of films. Moreover, the content of ĸ-carrageenan was closely related to the release of procyanidins, and the film containing 1% (w/w) gelatin, 1% (w/w) ĸ-carrageenan, and 2% (w/w) procyanidins (G/C1:1/P) showed the lowest total release of procyanidins in 50% and 95% ethanol simulants. Gelatin/ĸ-carrageenan films with procyanidins could be used as a controlled-release film for food packaging applications.