to replace natural rubber or to be introduced in a polyurethane matrix. However, the introduction of BSG resulted in diminished properties, which could in part be counterbalanced by the addition of GTR. Finally, Hejna et al. have studied in detail the impact of BSG as filler with various polymer matrixes (NFC, PCL), and the interactions with them. [125] They showed that the proteins contained in BSG improved the interfacial compatibility by participating in Maillard reactions to form melanoidins. Extrusion temperature was found to be the most determining factor for these reactions, more present at higher temperature (> 180°C), doubling the antioxidant power but bringing a strong brown colouration of the polymers. However, despite the good compatibility, BSG addition showed to be detrimental for mechanical and thermal performances. Furthermore, terpenes and terpenoids were liberated during the extrusion step that can be harmful for human health and the environment.