Valorization of Sulphur-Rich Proteins from Agro- Industrial Waste and Co-Products for the Development of Bioplastics: Thermoprocessing and Characterization of Feather Keratin/Gliadin Blends

Biopolymers based on plant and animal proteins are interesting alternatives in the development of films with future prospects as food packaging. Considering that in recent years there has been an increasing interest in the valorization of agro-industrial residues and by-products and that the blending of polymers can lead to materials with improved properties, in this work, keratin-rich feather fibers and gliadins were blended at different ratios in order to develop sustainable and biodegradable films. Control gliadin G100, feather F100 films and their blends at 3:1 (G75F25) , 2:2 (G50F50) and 1:3 (G25F75) ratios were successfully developed through thermoprocessing. The physical properties were differentiated as a function of the concentration of both polymeric matrices. Although gliadins showed higher hydrophilicity confirmed by its highest swelling degree, films with high gliadin ratios exhibited lower water permeability values at low and medium relative humidities. On the other hand, the feathers displayed the highest Young´s modulus values and provided oxygen barrier to the blends, principally at the highest relative humidity. In conclusion, the blend of these protein-based polymers at different ratio resulted on interesting composites whose physical properties could be adjusted.