The presentation of our results is organized as follows. First, we describe the experimental BO data collection and the qualitative convergence of the surrogate models. We furthermore consider how useful our two different data collection strategies (Fig. ) were in this task. Next, we analyze the surrogate models to gain insight into the extraction process and its underlying chemistry. Lastly, we show how to simultaneously optimize lignin yield and structural properties to obtain extraction conditions tailored for specific applications in lignin valorization.