Safety Assessment of Keratin and Keratin-Derived Ingredients as Used in Cosmetics

Keratin from Animal By-Products: Structure, Characterization, Extraction and Application-A Review

Keratin is a structural fibrous protein and the core constituent of animal by-products from livestock such as wool, feathers, hooves, horns, and pig bristles. This natural polymer is also the main component of human hair and is present at an important percentage in human and animal skin. Significant amounts of keratin-rich animal tissues are discarded worldwide each year, ca. 12 M tons, and the share used for keratin extraction and added-value applications is still very low. An important stream of new potential raw materials, represented by animal by-products and human hair, is thus being lost, while a large-scale valorization could contribute to a circular bioeconomy and to the reduction in the environmental fingerprint of those tissues. Fortunately, scientific research has made much important progress in the last 10-15 years in the better understanding of the complex keratin architecture and its variability among different animal tissues, in the development of tailored extraction processes, and in the screening of new potential applications. Hence, this review aims at a discussion of the recent findings in the characterization of keratin and keratin-rich animal by-product structures, as well as in keratin recovery by conventional and emerging techniques and advances in valorization in several fields.

Fabrication of Wet-Spun Wool Keratin/Poly(vinyl alcohol) Hybrid Fibers: Effects of Keratin Concentration and Flow Rate

Sheep wool is one of the most common wastes derived from agriculture and also a great source of keratin. In this study, chemical reduction and alkali hydrolysis methods of extracting keratin from wool were studied for the purpose of reusing the waste wool, and the products were used to fabricate wet-spun hybrid fibers by mixing with PVA. The comparative yield of the two extraction methods was investigated, and the optimal precursor concentration ratio for keratin extraction was identified. The effects of keratin concentration and wet-spinning flow rate on the mechanical properties of fabricated fibers were studied. Therefore, this study encourages the further investigation of wool keratin-based hybrid biomaterials, which could provide a new way to reuse waste wool.