Valorization of the lipid fraction of rice bran via supercritical CO2 and green solvent extraction processes

Efficient food resources management, particularly through minimization of waste across the production and supply chain, is essential for creating a resilient, circular agri-food system. The rice industry is one of the largest sectors in agri-food, supporting over half of the global population. This work focuses on valorizing the lipidic fraction of rice bran, a major by-product of rice processing, to contribute to reducing the environmental impact of rice production. Novel purification processes of rice bran wax (RBX) from rice bran are presented, together with their environmental impact assessment. Rice bran butter (RBB) was initially extracted using supercritical CO2, followed by the separation of its main components, rice bran oil (RBO) and rice bran wax (RBX), through combinations of different physical unit operations including crystallization, centrifugation, solvent extraction and filtration. The purification strategies developed involved green solvents such as ethanol and isopropanol, compared to the commonly used hexane. The purified products were characterized in terms of their chemical properties via chromatographic techniques. Differential Scanning Calorimetry (DSC) and X-ray diffraction were used to determine structural and thermal properties of the material extracted. A Life Cycle Assessment (LCA) was also conducted to determine the environmental impact of the designed extraction and separation processes. The LCA highlighted that the optimal process configuration balances wax extraction yield, energy consumption, and solvent use. Process #2 using ethanol emerged as the most sustainable option, achieving the highest performance with the lowest environmental impact.