The PRIMo project ("Photoionisations-Reaktor-Inlineanalyse für Moderne Lebensmittelröstung") addresses a critical gap in modern food processing: the lack of selective, real-time chemical process control in coffee roasting. Coffee roasting is a highly dynamic process driven by complex reaction networks, including Maillard reactions, Strecker degradation, caramelisation, and pyrolysis, that collectively determine the aroma profile and quality of the final product. Despite its industrial importance, coffee roasting is still largely controlled using only temperature and roasting time, which do not fully reflect the complex chemical reactions occurring during the process. In contrast, pressure has received comparatively little attention as a process variable in coffee roasting, despite its well-established influence on chemical reaction pathways and reaction kinetics. 

A central innovation of PRIMo is the introduction of pressure as an active process parameter, combined with inline chemical analysis. To this end, a modular high-pressure roasting reactor (up to ~100 bar and ~300 °C) is being developed and coupled to a photoionisation mass spectrometer (PI-MS). Using both single-photon ionisation (SPI) and resonance-enhanced multiphoton ionisation (REMPI), the system enables soft, non-fragmenting ionisation of volatile organic compounds directly from the gas phase during roasting, with a time resolution in the sub-second range. This allows the continuous, real-time monitoring of key aroma markers such as pyrazines, furanones, and aldehydes throughout the entire roasting process. 

One of the main technical challenges is the development of a high-pressure-compatible sampling interface. This interface must allow controlled pressure expansion while preventing condensation and analyte loss, ensuring reliable transfer of the process gas into the ionisation source. The acquired spectral data will be processed using multivariate statistical methods and machine learning techniques to correlate real-time mass spectra with roast quality indicators such as roast degree and aroma profile. Ultimately, this approach aims to support the development of data-driven, closed-loop process control strategies for coffee roasting. 

The project is carried out in collaboration with Photonion GmbH, Dustec Hochdrucktechnik GmbH, and PROBAT-SE, combining expertise in analytical chemistry, high-pressure engineering, and industrial roasting technology.