Tartaric acid-crosslinked chitosan-based quaternary ammonium/phosphonium salt–PVA multifunctional composite films for enhanced food preservation

Chitosan, a renewable resource, is increasingly studied for its food packaging applications. In this study, chitosan (CS) was used as a raw material to synthesize two derivatives—dodecyl chitosan quaternary ammonium salt (DMDBC) and triphenyl chitosan quaternary phosphonium salt (TPPBC). These were combined with polyvinyl alcohol (PVA) to develop a multifunctional food packaging material with enhanced physical, antibacterial, and antioxidant properties. The resulting composite films exhibited excellent homogeneity and biocompatibility. Strong intermolecular hydrogen bonding among DMDBC, TPPBC, and PVA was confirmed, contributing to the amorphous structural characteristics of the films. Among the various formulations, the film containing 6 % tartaric acid (6 % TA-C12) demonstrated the best mechanical strength, water vapor barrier, and oxygen barrier properties. Incorporation of DMDBC and TPPBC endowed the films with remarkable bioactivities, achieving DPPH and superoxide radical scavenging rates of 81.2 % and 35.6 %, respectively, along with inhibition zone diameters of 32.3 mm ( S. aureus ) and 29.5 mm ( E. coli ). Compared to commercial polyethylene (PE) films, the developed films effectively delayed spoilage and extended the shelf life of strawberries by up to nine days. These high-performance composite films hold strong potential as sustainable alternatives to conventional PE packaging materials in the field of fruit preservation.