Active chitosan films crosslinked by vanillin-derived dialdehyde for effective fruit preservation

s To address the vulnerability of fruit during the storage period, an economical and green active film package is urgently required to extend the shelf life. In this work, a vanillin-derived dialdehyde (DV) was successfully synthesized, and further employed as the crosslink agent into chitosan matrix via the formation of Schiff base. The obtained film (CS-DV) with compact structure exhibited excellent stability, mechanical strength, barrier properties and bioactivities. The experimental results indicated that the tensile fracture stress was enhanced by 3.8 ∼ 4.5 times in comparison with pure chitosan (CS) film. Due to the contained DV molecules, the UV irradiation in range of 250 ∼ 400 nm was almost blocked by CS-DV films. Meanwhile, the diffuse of oxygen/water vapor across the CS-DV film were suppressed, preventing the dehydration and nutrient oxidation. Moreover, CS-DV films displayed high radical scavenging capacities, where the highest DPPH and ABTS radical scavenging ratios were evaluated to be 82.20% and 99.39%, respectively. In combination with their strong antibacterial activities against Staphylococcus aureus and Escherichia coli , CS-DV film package could significantly extend the shelf life of raspberry fruits with high preservation efficiency. This bio-based film only consists chitosan and vanillin derivative without any additives, showing potential as packaging material for agricultural and food products.