Development and application of dual-functional Fe-D-Arg complex fortified cellulose crystals based smart active packaging films.

Currently, there is an increasing demand in the development of colorimetric ammonia-responsive smart packaging materials for real-time monitoring of food freshness. Herein, a novel dual-functional Fe-D-Arg (where D-Arg refers to D-arginine) complex nanocrystal with inherent antimicrobial activity and colorimetric ammonia-responsive characteristic was constructed and then incorporated into a cellulose nanocrystal (CNC) matrix to produce high-performance active smart films. The effects of Fe-D-Arg complex on the structural, physical, and functional properties of the CNC films were investigated. The results revealed that the Fe-D-Arg complex nanocrystals were uniformly dispersed within the CNC matrix, thereby markedly improving the film's UV-shielding capability (nearly 100 % efficiency), mechanical strength (55.89 MPa), ductility, hydrophobicity, and water barrier properties. Furthermore, incorporation of the Fe-D-Arg complex endowed the films with long-term color stability and excellent antimicrobial activity (over 95 %) against Escherichia coli and Staphylococcus aureus. The CNC/Fe-D-Arg composite films also possessed favorable colorimetric responsiveness to ammonia. When applied for shrimp freshness monitoring, these composite films showed distinct color changes corresponding to the increasing levels of total volatile basic nitrogen (TVBN). These results suggest that the developed CNC/Fe-D-Arg composite films are promising candidates for use as active and smart food packaging materials.