Bioplásticos a partir de proteína de guisanteprocesado, caracterización y ciclo de vida

Abstract

The United Nations enacts the 17 Sustainable Development Goals (SDG) with the aim of ending poverty, protecting the planet and ensuring that all people enjoy peace and prosperity by 2030. Among them, we find Goal 12 on efficient management of natural resources, which reduces the amount of waste. To this end, in recent years, waste and by-products from the industry are being used to produce sustainable materials that are also eco-friendly (in a circular economy context that makes use of wastes or by-products as raw material). Materials that seek to replace conventional petroleum-based plastics are located in this research line. These materials are called bioplastics because they are biodegradable, have a natural origin or because they meet both qualities. In this sense, the main objective of this project was the development of bioplastics from a by-product, from the agri-food industry, rich in pea protein. Thus, the first stage of the thesis consisted of the characterization of the raw material, based on its chemical and amino acid composition, its solubility and even its thermal properties. Next, the fabrication of bioplastics was carried out. Classical thermoplastic polymer processing techniques (extrusion, compression moulding, etc.) have been widely used to obtain different protein-based bioplastic materials. In this study, bioplastics have been obtained by injection moulding. This technique consists of a previous mixing of the protein and a plasticizer (glycerol) followed by an injection stage. Therefore, the influence of the processing parameters involved has been studied, evaluating both the protein/plasticizer ratio, the mixing time or the injection conditions such as the injection pressure, the moulding time or the temperature of the mould. The reference bioplastic has been fabricated with the processing conditions selected above. In this way, the influence of different crosslinking methods on the properties of the bioplastics obtained has been analyzed. Three methods of crosslinking have been studied. Specifically, a thermal treatment and UV radiation have been used as physical methods, genipin and aldehydes as chemical methods and transglutaminase as an enzymatic method. Regarding the different methods of crosslinking, physical crosslinking generates new bonds by additional physical phenomena, while chemical and enzymatic crosslinking generate new bonds through chemical reactions caused by chemical compounds or the use of enzymes. To conclude the project, an environmental assessment of a process using waste/by-products is included to understand the process in the context of the circular economy. For this reason, a preliminary analysis of the bioplastics obtained has been carried out, with the different modifications carried out, through a preliminary study of the life cycle of its fabrication process.