Carboxymethyl glucuronoxylan /PVA/nano ZnO composite films for blueberry preservation: The effects of nano-ZnO on the packaging properties of the composite films.

Fruits are susceptible to deterioration during storage, while petroleum-based plastics cause environmental concerns. In this study, carboxymethyl xylan (CMX) was synthesized and blended with polyvinyl alcohol (PVA) and nano-ZnO to fabricate multifunctional composite films via solution casting for blueberry preservation. Nano-ZnO served as a functional filler to enhance mechanical properties, barrier performance, and UV resistance. The effects of nano-ZnO content, particle size, and CMX/PVA ratio on film properties were systematically investigated. The optimized C-5 film (PVA: CMX: nano-ZnO = 0.81 g:0.09 g:0.045 g) exhibited 106.73% increase in tensile strength, 63.2% and 6.34% reductions in oxygen and water vapor transmission rates, respectively, along with favorable antibacterial activity. The shelf life of blueberries was extended by approximately 7 days at 25 °C and 30% RH. These results demonstrate that nano-ZnO incorporation endows the films with excellent UV shielding, antibacterial properties, and fresh-keeping performance, providing a promising strategy for value-added utilization of xylan.