**6. Conclusions**

The potential for reusing natural by-products and wastes from different sources was reviewed in this chapter, describing their most attractive properties and

characteristics. The most recent innovations and developments in this area were listed and presented, showing a novel possible way for the development of technical and functional textiles. The main potential applications for the valorization of whey protein by the production of textile fibres have been described, as well as by its application as a textile finish. The different applications already tested and the main products already available on the market for sustainable alternatives to produce genuine leather were also listed. Although these types of applications at an industrial level have some limitations, as cost-effectiveness ratio, permanence of the intrinsic properties of the substrates and durability to the laundering, for example, the reuse of these natural by-products and wastes as a bio-resource in the demanding textile sector presents itself as an attractive alternative.
