Bio-templated nanocellulose/ZnO hybrids reinforced PVA/chitosan films with synergistic antibacterial activity for enhanced food preservation

Antibacterial food packaging plays a crucial role in preserving food quality and extending shelf life. Polyvinyl alcohol (PVA) is widely used in food packaging, but its lack of inherent antimicrobial properties restricts its wide applications. Zinc oxide (ZnO) is an effective antibacterial agent. However, the uniform dispersion of ZnO nanoparticles (NPs) remains a challenge. To address this, hybrid NPs were constructed using cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) as bio-templates with ZnO in-situ loading onto their surfaces. These hybrid NPs were then incorporated into PVA/chitosan (4:1, w/w) compound to prepare transparent and antibacterial packaging films. The results indicate that ZnO loaded on the surfaces of CNC or CNF exhibited distinct morphological features. Antibacterial tests revealed that the combination of CS and ZnO exhibited organic-inorganic synergistic antibacterial activity. Furthermore, the hybrid NPs enhanced the mechanical strength and hydrophobicity, with CNF-ZnO showing superior reinforcement. Preservation tests on strawberry demonstrated that the films outperformed PE and PVA/CS films, indicating their effectiveness in maintaining fruit quality and prolonging shelf life.