We acknowledge the SOLEIL and SSRL synchrotrons for the provision of beamtime. U.B. and L.B. acknowledge support from the France–Stanford Center for Interdisciplinary Studies Program and the LabEx PATRIMA (Agence Nationale de la Recherche, 10-LABX-0094) / Fondation des Sciences du Patrimoine for U.B.'s invited professorship at Université Paris-Saclay. R.S.P.F. acknowledges the Flinders University Outside Studies Program and the Australian Synchrotron International Synchrotron Access Program for a research visit to Stanford University. We thank Alessia Andreotti from the Department of Chemistry and Industrial Chemistry of the University of Pisa for her help with the GC-MS analysis of polysaccharide gums. R.G.'s PhD work was funded by UVSQ and Synchrotron SOLEIL. R.G. acknowledges support from Université Paris-Saclay for the financing of a visit to Stanford. R.G. acknowledges support from the State Scholarships Foundation of Cyprus for doctoral studies.

FT-IR.zip: FT-IR dataset GC-MS.zip: GC-MS dataset ICP-MS.zip: ICP-MS dataset Py-GC-MS.zip: Py-GC-MS dataset XRS C K-edge.zip: X-ray Raman spectroscopy dataset at the carbon K edge XRS O K-edge.zip: X-ray Raman spectroscopy dataset at the carbon O edge