The transition to a green and sustainable economy requires efficient utilization of our natural resources. Lignin, as a part of lignocellulosic biomatter, is an example of a naturally abundant, but under-utilized, resource . Lignin is currently produced in large quantities as a by-product of pulping processes. Valorization of lignin into high-value industrially relevant products, materials or chemicals , can therefore substantially increase both the sustainability and revenue of biorefineries . Recently, some of us have developed AquaSolv Omni (AqSO), a green biorefinery for the integrated utilization of all biomass components, with special focus on the lignin-containing streams . In the AqSO process, hydrothermal treatment (HTT) is first applied to the biomass feedstock and the resulting solids are subsequently washed with a solvent. The aqueous environment of HTT eliminates the need for extra chemicals in the reaction medium, which makes AqSO a green process given a suitable choice of solvent.