Development of novel sodium alginate-based light-responsive controlled-release active packaging film

Developing intelligent active packaging films with responsive controlled-release properties for food preservation is highly desirable. Herein, a light-responsive carrier material PBA-IRMOF-3 was prepared by modifying azobenzene 4-carboxylic acid (PBA) with azobenzene photosensitive group on isoreticular metal-organic framework material-3 (IRMOF-3). PBA-IRMOF-3 loaded with active substance carvacrol (CA) was added to the sodium alginate (SA) matrix to prepare the light-responsive controlled-release active film PMC@SA. Upon alternating ultraviolet (UV) and visible light (Vis) irradiation, the azobenzene group of PBA-IRMOF-3 underwent structural isomerization, which played the role of "impeller-stirring" to promote the release of CA, resulting in the PMC@SA film exhibited light-responsive controlled release characteristics. Furthermore, the PMC@SA film demonstrated notable hydrophobicity (water contact angle: 69.67 ± 1.21°), excellent water vapor barrier properties (water vapor transmission rate: 559.68 ± 5.99 g·d^-1·m^-2), and effective light-blocking performance (nearly zero transmittance in the 250-380 nm). UV radiation did not significantly affect the mechanical and physical properties of the film. Evaluation of pork preservation revealed that the PMC@SA film significantly improved the pork quality, particularly after UV irradiation (P < 0.05). These results highlight the potential application value of the film in the field of responsive controlled-release food packaging.