Dealkalized lignin-crosslinked konjac glucomannan films: Structure, antioxidation, and ultraviolet-blocking properties for fresh-cut eggplants preservation

This work introduced paper industry by-product dealkalized lignin (DL) as a natural modifier into the konjac glucomannan (KGM) system to overcome the deficiencies of KGM, such as poor mechanical properties and weak ultraviolet (UV)-blocking performance, addressing the urgent demand for renewable and biodegradable functional materials in packaging. Through the chemical crosslinking action of epichlorohydrin (EPI), the effects of DL content (0.1%, 0.3%, and 0.5% w/v) on the microstructure, thermal stability, mechanical properties, gas barrier properties, antioxidant activity, UV-blocking properties, and biodegradability of the composite films were systematically investigated. The results showed that EPI could successfully promote the formation of a stable three-dimensional (3D) network structure between KGM and DL, particularly at 0.3% (w/v) DL content. When the DL concentration was 0.5%, the ductility of the composite films was significantly enhanced, with a maximum elongation at break (EAB) of 57.61%. In addition, the antioxidant activities (ABTS radical scavenging rate: 85.83%) and UV-blocking properties of the composite films were remarkably improved. Experiments on fresh-cut eggplants preservation further confirmed that the KGM/DL films effectively delayed weight loss, hardness reduction, total phenolic content (TPC) reduction, and lipid peroxidation of eggplants, demonstrating good application potential. Therefore, this study provides an effective strategy for the high-value utilization of industrial by-products and the development of new green materials.