The automated process control in the chemical and biotechnological industry requires measurement techniques that record the educt and product concentrations in real time either inline or online. It also has to be easily integrated into the process engineering environment. Of the various optical spectroscopy techniques, MIR and Raman spectroscopy have the highest selectivity since they provide information on the fundamental vibrations of molecules. During the aerobic batch fermentation of Saccharomyces cerevisiae, the degradation of glucose is analyzed and the ethanol concentration is measured.

The major advantage using optical probes is that the measurement technique can be spatially separated from the process allowing additional quantification through an at-line measurement of weighed substance concentrations and fermentation samples. Raman spectroscopy is more selective than NIR and UV / VIS spectroscopy and thus better suited for this application. Furthermore, it is predestined for bioprocess tracking since the water spectrum has a lower dominance resulting in less interference.