Valorization of keratin from food wastes via crosslinking using non-toxic oligosaccharide derivatives.

• Crosslinkers were developed from oligosaccharides for valorization of keratin wastes. • Oligosaccharide crosslinkers were more effective than other non-toxic crosslinkers. • Crosslinking simultaneously improved strength and elongation of keratin films. • Reaction mechanism between sugar crosslinker and keratin was revealed using analogs. • Relationship between tensile properties and crosslinking degree was quantified. Oligosaccharide derivatives were developed to crosslink keratin materials from poultry feathers, swine bristles and ox hairs to valorize these major wastes from meat industry. Global butchery generates more than 8,600,000 tons of keratinous wastes annually. Keratin was considered a promising resource for developing bio-based products as alternatives to petroleum products. Regenerated keratin products, such as films, usually showed insufficient mechanical properties, and required external crosslinking. However, most crosslinkers for proteins are either toxic, expensive, or with low efficiencies under mild conditions. In this research, regenerated keratin films were crosslinked by oxidized sucrose, a safe and potent bio-polyaldehyde. The crosslinker with verified low toxicity improved both tensile strength and elongation of keratin films, surpassing many other safe crosslinkers. Mechanism of the crosslinking reaction was proposed as forming Schiff bases and aminals and verified via 1H NMR and 13C NMR. Relationship between tensile properties and crosslinking degree of keratin films was also quantified. [ABSTRACT FROM AUTHOR]