EGCG-functionalized deacetylated konjac glucomannan/carboxylated cellulose nanofiber films: Development, characterization, and application in antibacterial preservation of fresh-cut fruits.

Abstract

Fresh-cut fruits are susceptible to microbial contamination that leads to quality deterioration. In short-term distribution scenarios oriented toward consumers, there is a need for active packaging materials that are contact-safe and capable of exerting rapid antibacterial effects. The present study incorporated epigallocatechin gallate (EGCG) into a deacetylated konjac glucomannan/carboxylated cellulose nanofibers (DKGM/CCNF) matrix to prepare bio-based antibacterial films loaded with low and high EGCG concentrations (LEG-DKGM/CCNF and HEG-DKGM/CCNF). The effects of EGCG incorporation on the structure, mechanical properties, and barrier performance of the composite films were systematically studied, and the films were applied to fresh-cut fruits. Results indicated that EGCG formed hydrogen bond interactions with the DKGM/CCNF network and altered the film's microstructure, enhancing thermal stability while reducing the tensile strength and elongation at break of the composite films. In vitro antibacterial tests demonstrated that EGCG-loaded composite films inhibited foodborne pathogens associated with fresh-cut produce contamination, including Staphylococcus aureus, Listeria monocytogenes, and enterohemorrhagic Escherichia coli, with more pronounced inhibition against S. aureus. Further using S. aureus-inoculated fresh-cut apple as a model, after short-term (1h) coverage with the films, LEG-DKGM/CCNF and HEG-DKGM/CCNF films achieved an inhibition rate of over 80% against S. aureus. In addition, fresh-cut apple storage tests showed that EGCG-loaded films reduced browning index and helped maintain the appearance and firmness of fresh-cut apples during storage. Overall, the EGCG-functionalized DKGM/CCNF films provide a feasible solution for developing bio-based antibacterial packaging with rapid antibacterial and preservation functions for fresh-cut fruits.