Revaluation of a Soy Protein By-product in Eco-friendly Bioplastics by Extrusion

Agri-food waste and by-products are being increasingly revalued, exploiting their potential. One of the attractive alternatives is their use as raw materials for the production of bioplastics due to their high protein content, generating eco-friendly bioplastics, since they come from renewable sources and are biodegradable. However, their industrial scalability is being difficult mainly due to their manufacturing process, which is generally expensive. Therefore, the objective of this work was to revalue a by-product from the industrial production of soybean oil as a raw material to process bioplastics by extrusion moulding (a process widely used in the manufacture of plastics). In this way, the use of this raw material could reduce costs and facilitate the scalability of these products. The results obtained in this work show that this by-product is a suitable raw material for the development of bioplastics. Furthermore, extrusion allowed obtaining bioplastics with different mechanical characteristics and water uptake capacity by modifying the temperature and screw speed of the process. Thus, higher temperatures generated better mechanical resistance, while lower temperatures improved the water uptake capacity. These results demonstrate the great capacity of this raw material and processing technique for the large-scale adaptation of bioplastics that can be used in different applications, such as packaging and hygiene products.