Multifunctional chitosan-based indicator films containing composite pigments stabilized by extracellular and cell wall polysaccharides from Auricularia cornea var. Li. waste for visualization of salmon freshness.

Smart packaging can indicate the meat freshness through color variations of natural pigments within the films, whose instability have hindered their industrial application. This study developed multifunctional indicator films (CS-ACPS-CB) that possessed ultraviolet resistance, antioxidant properties, and pH sensitivity by incorporating extracellular and cell wall polysaccharides from Auricularia cornea var. Li waste (ACPS) into chitosan (CS) matrix with curcumin/betalain as indicators. Results revealed the extracellular component was acidic heteropolysaccharides, while the cell wall comprised glucose, mannose, xylose, rhamnose and galactaric acid. The electrostatic interactions and hydrogen bonding between cell wall polysaccharides and CS strongly stabilized composite pigments, allowing for controlled release at pH above 8.0. Additionally, CS-ACPS-CB demonstrated color changes corresponding to increases in total volatile basic nitrogen values, effectively signaling the progressive spoilage of salmon. These findings offer an environmentally friendly solution for utilizing Auricularia cornea var. Li waste and a sustainable application for ACPS in smart packaging materials.