New Active Biopolymers and Chitosan-Based Films from Non-Native Crayfish Shell

Freshwater crayfish impact ecosystems and the food industry. The aim of the study was to valorize shells from the invasive crayfish, Faxonius limosus, to extract novel bioactive biopolymers and prepare biodegradable films, thereby contributing to economic and environmental sustainability. Chitin from crayfish shells was isolated and converted into chitosan through a new protocol to retain astaxanthin, with a shorter procedure, reduced use of organic solvent and energy consumption. The resulting biopolymers were used to prepare chitosan-based films. Thermal, spectroscopic, barrier properties, and surface microstructure of the biomaterials were identified. Spectrophotometric and chromatographic techniques were used on crayfish shells and biopolymers to track astaxanthin throughout the extraction and formulation processes. Crayfish chitosan film exhibited higher stiffness, enhanced thermal stability and water vapor barrier properties with respect to commercial chitosan films. 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl antioxidant assays showed that all crayfish biomaterials exhibited antioxidant activity. Astaxanthin greatly enhanced the antioxidant properties of crayfish chitosan, but chemical degradation during film processing limited this effect in the film matrices. Therefore, crayfish-derived biopolymers and films are promising for incorporation into functional foods and active packaging and support shell waste reduction, offering a viable strategy for managing and valorizing invasive species.