Sustainable citrus waste biorefining as a source of value added bioproducts

Abstract

The main challenge which limits the wider uptake of biobased chemicals, produced by biological transfonmation via microbial fermentation, as altematives to those derived from petroleum is the cost of production. The majority of the direct costs of such bioprocesses are accounted for by the substrate used. This presents an opportunity for the development of biorefineries engineered to take sugar (carbon) and nutrient rich wastes and by-products and tum them into value added biomolecules. One such inefficiently used agro-industrial waste is citrus processing waste, predominately orange juicing waste. In a typical orange juicing process around 50% of the processed mass of oranges leaves as waste, which is usually disposed of by incineration to recover some energy. As a sugar rich waste stream orange peels can be used as a low cost substrate to obtain biomolecules. The key aim of the current joint proposal is to develop a technically feasible citrus waste biorefinery, by engineering a bioprocess to obtain a sugar rich fermentation media for the production of biocolorants using Ta/aromyces amestolkiae and biopolymers using Cupriavidus necator H16. Alongside the development of the bioprocess as a whole, the environmental and economic irnpacts, of such an orange juicing waste biorefinery will be assessed on a life cycle basis. The proposed work will support the current Young Investigators FAPESP project, n. 2014/01580-3, entitled "Biotechnological process for the development of new natural colorants from microorganisms for industrial application", which is coordinated by Dr. Valéria C. S. Ebinuma. Furthermore, this collaboration will underpin the development of a broader, high quality biorefining research network to bring together Brazilian (where sugarcane to ethanol biorefining is well established) and UK biorefining expertise, promoting the valorisation of agricultural waste streams, including citrus by-products, through transformation into value-added bioproducts. The fonmation of this network will enable two-way knowledge exchange and provide the foundation for future funded joint-projects. (AU)