Insights into Supercritical and Near-Critical Fluid Technologies for the Processing of Food using Raman Spectroscopy

Supercritical and near-critical fluids offer innovative and sustainable process concepts for various applications. Especially in the field of food processing these fluids provide several benefits compared to conventional processing.
Due to its special properties, compressed CO2 in particular can open up completely new process paths or replace the frequently environmentally critical organic solvents in conventional extraction processes. For the development and design but also for the optimization of such processes, the complete process mechanism and the key process parameters have to be known. Especially optical measurement techniques exhibit a high potential for the in-line process analysis.
This thesis demonstrates the feasibility of Raman spectroscopy for the in-line monitoring in the field of supercritical and near-critical fluid food processing. The non-invasive measuring technique provides insights into the dense phase carbon dioxide pasteurization of liquid foodstuff, the pressurized CO2 drying of fruits and vegetables, and the supercritical fluid extraction of hop. For the analysis of these processes, self-developed Raman sensors were used. The impact of interfering fluorescence signals on the Raman spectra could be completely eliminated with mathematical and experimental methods.