Laser-assisted extraction of food ingredient compounds from organic microparticle suspensions due to pulsed laser diffusion enhancement in liquids (PUDEL) based on coffee as a model material

• Applicants: Professor Dr.-Ing. Stephan Barcikowski; Professor Dr. Torsten Schmidt
• Subject Area: Analytical Chemistry ; Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571997310

Pulsed Laser Diffusion Enhancement in Liquids (PUDEL) is an innovative technique using ultrashort-pulsed lasers to locally heat and rearrange surface atoms in micro- and nanoparticle dispersions, without altering particle size or morphology. While PUDEL has shown promise for tuning structural defects in inorganic catalysts, its potential for organic microparticle suspensions, such as those found in food processing, remains largely unexplored. This project aims to systematically investigate PUDEL’s effects on solid-liquid extraction profiles, using coffee as a model system. Potential benefits include accelerated extraction of aroma components, enabling e.g. rapid cold-brew coffee preparation, and the generation of novel aroma profiles. Our approach involves conducting PUDEL experiments with size-selected coffee particles in a custom flat-jet flow-through reactor, allowing precise control of irradiation parameters such as fluence and laser pulses per volume element (PPV). The aqueous extract and headspace of PUDEL-treated samples are analyzed to identify and quantify compounds that are depleted, enriched, or newly formed. This requires the adaptation and development of sensitive analytical methods, primarily based on LC-MS and GC-MS, supported by advanced statistical analysis to resolve subtle changes in complex matrices. The project is structured into defined, collaborative work packages: (1) examining input parameters such as coffee type and roasting degree to identify substances most responsive to laser-induced extraction; (2) correlating extraction yield with particle size, considering both surface area and laser absorption properties; (3) optimizing laser fluence to distinguish between regimes of degradation, global heating, and true PUDEL effects; (4) varying PPV to identify whether single-or multi-pulse effects are involved; and (5) performing kinetic studies to determine how PUDEL influences the speed of extraction. Although focused on coffee, the insights gained have the potential to be transferable to other food powders such as matcha or spices, potentially transforming extraction processes in food research and industry.

• DFG Programme: Research Grants