Green synthesis of citric acid-crosslinked ethanol lignin/carboxymethylcellulose films for fresh-cut apple preservation

Considering the non-renewable and non-biodegradable characteristics of conventional petroleum-based plastic films, their widespread use contributes significantly to environmental degradation. This study utilizes a green synthesis citrate-based chemical cross-linking strategy to improve the dispersion of ethanol lignin within the film, thereby promoting the development of a natural, safe, renewable, biodegradable, and environmentally friendly biomass-based functional food packaging material. A novel, multifunctional green food preservation film (ELA x C) was synthesized by employing CMC film as the substrate, ethanol lignin (EL) as the functional agent, and citric acid (CA) as the cross-linking agent. The influence of CA addition on the properties of the film was systematically examined. The results indicated that the ELA 0.2 C film exhibited an optimal elongation at a break of 8.0 %, a tensile strength of 28.49 MPa, and outstanding UV-blocking performance, effectively blocking 100 % of UVB and 99.2 % of UVA radiation. Furthermore, the ELA 0.2 C film exhibits antioxidant properties, gas barrier performance, and biodegradability. This film demonstrates significant potential as a multifunctional cling film for apple slices. Moreover, EL can be directly applied as a functional agent without the need for re-dissolution, thereby offering an innovative pathway for the efficient and environmentally sustainable utilization of lignin. • This study presents a straightforward and green method for the synthesis of lignin/ citric acid/ CMC composite films. • The composite films exhibited outstanding UV-blocking, antioxidant activity, and biodegradability. • The composite films show promise in a multifunctional and active food preservation material.