Synergistically Antibacterial and Antioxidant Catechaldehyde-Based Composite Bio-Coating for Enhanced Strawberry Shelf Life

Developing safe, non-toxic and high-efficiency coating materials for food preservation has become a critical research focus in the field of food packaging. In this study, a catechaldehyde-cross-linked gelatin/sodium hyaluronate (GHAP) composite coating was engineered to improve the antibacterial and antioxidant functionalities of gelatin. By optimizing the cross-linking ratio, a GHAP4 film with superior overall properties was obtained. Fourier transform infrared (FTIR) analysis confirmed that the aldehyde groups of catechaldehyde participated in cross-linking reactions with the amino groups of the gelatin–sodium hyaluronate matrix. The GHAP4 film exhibited excellent antioxidant activity, achieving a DPPH radical scavenging rate of 96.8%, and showed strong antibacterial effects against Escherichia coli and Staphylococcus aureus . Furthermore, cytotoxicity tests suggested that all concentrations of GHAP4 solution exhibited cell viability exceeding 100%. Zebrafish toxicity tests showed that the GHAP film had no significant toxicity to zebrafish, with no deformities or deaths observed. Preservation experiments using strawberries as a model sample showed that the GHAP4 coating effectively slowed down changes in colour, titratable acidity and soluble solid content, extending the shelf life from 4 to 8 days. This study provides new ideas and a theoretical basis for the application of natural polymer-based functional coatings in fruit and vegetable preservation.