Protein-Based Bioplastics from Biowastes: Sources, Processing, Properties and Applications

Even though proteins have been used for the development of plastic materials for a long time, their use has not proliferated when compared to other plant materials, such as starch or cellulose. Moreover, the current trend in the bioplastic market is based on polylactic acid or polyhydroxycarbonates, such that a feasible and globally accepted formulation of protein-based bioplastics is still pursued. The physical instability along time, together with the need of using non-food resources are drawbacks for the development of protein-based materials. Since lots of biowastes from the industry contain a considerable amount of proteins, the application of these natural polymers in the production of biodegradable materials would seem to benefit from a revalorisation of those resources, in agreement with a circular economy. This review is aiming for a comprehensive analysis of the current status of protein-based bioplastics, considering the main plant and animal sources that have been used, describing different wet and dry processing techniques and conditions, as well as the most reported properties (thermal, mechanical, optical, among others).