From Poultry Wastes to Quality Protein Products via Restoration of the Secondary Structure with Extended Disulfide Linkages

We develop an approach to efficiently restore the secondary structure of keratin via lengthy disulfide crosslinking for the development of high-value products from feather wastes. For decades, good flexibility and wet stability of poultry feathers could not be retained in the regeneration of keratin products due to low recovery of original secondary structures of the protein. In this research, we find that extension of intrinsic disulfide linkages in keratin restores not only the degree of crosslinking but also secondary structures because lengthy crosslinkages can increase the collision possibility of thiol groups on different protein backbones and help sliding of molecular chains. Using dithiothreitol for disulfide extension, breaking elongation, wet strength, and weight retention in water of generated keratin films improved 600, 1100, and 10%, respectively, compared to films without disulfide extension. Disulfide extension did not change the cytocompatibility of keratinous products. The new approach makes industrial applications of keratin products with good performance feasible.