Development of a self-healing and biodegradable secalin-based film with dynamic covalent crosslinking for smart food...

With growing concerns over plastic pollution and mechanical damage during food distribution, the development of biodegradable and smart packaging materials has gained increasing attention. In this study, a novel self-healing protein-based film was developed using secalin (SEC), a rye-derived prolamin known for its film-forming capability. A dual strategy was employed, in which glutathione (GSH) increased chain mobility by disrupting internal interactions. At the same time, dialdehyde dextrin (DAD), a biodegradable crosslinker, created dynamic imine bonds to reinforce the matrix. This combination allowed the fabrication of films with desirable mechanical integrity and self-healing capabilities. Formulation conditions were optimized using response surface methodology (RSM) to achieve a favorable balance between mechanical properties and reparability. The optimized SEC/DAD/GSH film exhibited high transparency, effective UV-B and UV-C blocking, and significantly reduced water vapor and oxygen permeability compared to that of SEC control films. SEM and FTIR analyses, along with free functional group quantification, confirmed the formation of a dense, and uniform dynamic network. Upon water stimulation for 20 min, the film recovered approximately 85.89 % of its tensile strength, 80.16 % of elongation at break, and 88.87 % of Young's modulus. The film also demonstrated antioxidant and antimicrobial activity, as well as full biodegradability. Applied to fresh strawberries, the film effectively restored barrier integrity after minor damage, reducing moisture loss and oxidative degradation, and extending shelf life. These findings underscore the potential of this sustainable packaging platform, which leverages protein structural reconfiguration and dynamic bonding to meet the functional demands of high-moisture, perishable foods.