Raman spectra files and reference concentration data from malic acid fermentations with Ustilago trichophora

This data repository accompanies the publication “Raman Spectroscopy–Based Glucose Feed Control Automates Malic Acid Fermentation.” The study demonstrates that Raman spectroscopy combined with Partial Least Squares (PLS) regression can be used for closed-loop glucose feed control to automate malic acid fermentation. Provided here are the Raman spectra files and reference concentration data that were used to calibrate and validate the PLS model. These include the pure component spectrum of water, mixture spectra of glucose, malic acid, and succinic acid in water, as well as the fermentation data. The Raman spectra were collected using an Rxn1 Raman spectrometer (400 mW, 785 nm, wavenumber range 150-3450 1/cm, 4 1/cm resolution, 3x10 s acquisition time, HoloGrams 4.1, Endress+Hauser AG, Reinach, Switzerland) equipped with a near-infrared short focus immersion optic (0 mm focal distance, Endress+Hauser AG, Reinach, Switzerland). Fermentations F1-F5 were monitored online in a cell-free bypass loop. For the fermentation with inline measurement, the optic was inserted through the headplate and fully submerged in the fermentation broth. Pure component and fermentation offline samples were measured manually in glass vials. Reference concentration data were measured via High-Performance Liquid Chromatography. A Thermo Fisher Ultimate 3000 (Thermo Fisher Scientific, Waltham, Massachusetts, United States) combined with a Rezex ROA-Organic Acid H+ (8%) LC Column 300 x 7.8 mm (Phenomenex, Inc., Torrance (CA), United States) and a RefractoMax 520 RI detector (Thermo Fisher Scientific, Waltham, Massachusetts, United States) was used. As the mobile phase, 25 mM sulphuric acid with a flow velocity of 0.8 mL/min at 20 °C was used.