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

A bio-based antibacterial film was fabricated by combining EGCG with DKGM and CCNF. • EGCG exhibited good antibacterial activity when acting on fresh-cut fruit flesh. • EGCG interacted with the film via H-bond, thereby increasing its structural ordering. • The incorporation of EGCG also enhanced the thermal stability of the DKGM/CCNF films. • The films inhibited >80% S. aureus after being covered on fresh-cut apples for 1 h. 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 (1 h ) 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. Download: Download high-res image (139KB) Download: Download full-size image