Animal keratin: Multifunctional biomaterial from slaughter by-products-extraction, functionality and applications

As a slaughter by-product, animal keratin exhibits a wide range of bioactive functions, including antioxidant, immunomodulatory, and skin-repair-promoting effects, making it an important biomaterial with excellent biocompatibility and significant application potential. Bioactive peptides derived from animal keratin can enhance physiological functions and improve health through multiple mechanisms, and these bioactivities have attracted increasing research attention in the fields of food, medicine, and cosmetics in recent years. While considerable research has focused on the physicochemical properties of keratin, substantial challenges remain in its functional development, extraction and processing, and commercialization. This review provides an in-depth analysis of the nutritional functions, extraction and processing techniques, and current status of product development for animal keratin, and discusses its potential applications and future research directions, offering a reference for its further development.