Self-assembled multifunctional antimicrobial composite films of humidity-responsive pterostilbene@β-cyclodextrin inclusion complexes/carboxymethyl cellulose/zein for fruit preservation

Abstract

Biodegradable active packaging materials have received extensive attention around the world due to food safety issues and environmental pollution caused by plastic packaging materials. In this study, we present a humidity-responsive multifunctional composite film self-assembled from carboxymethyl cellulose, zein, and cyclodextrin inclusion complexes (PTE@β-CD ICs). The results show that the addition of PTE@β-CD ICs can effectively improve the ultraviolet light barrier, elongation at break, surface hydrophobicity, and thermal stability of the films. Adding 10 wt% PTE@β-CD ICs reduces the water vapor and oxygen transmission rates of the composite films by 22 % and 91 %, respectively. In addition, it confers excellent antimicrobial ability to the films, with the inhibition rate for E. coli and S. aureus being greater than 80 %. The release of pterostilbene from the composite films results in humidity-responsive properties. Fruit preservation experiments further demonstrate that the composite film can delay the transpiration of blueberries and grapes, inhibit microorganism growth, and extend the shelf life of fruits by 50 %-80 %. Moreover, the film completely degrades within 13 days when buried in soil. Such a biodegradable, humidity-responsive, and multifunctional material has broad application prospects in food packaging, and provides a reference for the development of other stimuli-responsive packaging materials.