ISBN 978-3-8439-5486-0

978-3-8439-5486-0, Reihe Mikrosystemtechnik

Florian Tritz
Quantification of analytes from aqueous samples using a capture and release process: Diketones in beer and wine

221 Seiten, Dissertation Albert-Ludwigs-Universität Freiburg im Breisgau (2023), Softcover, B5

Zusammenfassung / Abstract

Beer quality control and brewing process monitoring are core competencies of any brewery. This includes, among other things, the determination of the concentration of vicinal diketones (VDKs). Vicinal diketones are formed during brewing at concentrations that are not sensory detectable if the process is performed correctly. However, if the brewing process is not optimally managed, the concentrations of vicinal diketones are too high (above 0.10 mg/l) and the beers are no longer usable due to a pronounced off-flavor. The aim of this research was to develop a detection system for the quantitative determination of vicinal diketones in beer and wine. For this purpose a copolymer was developed that reacts with the diketones and binds them. The polymer polyacryoyl hydrazide (PAH) with a hydrazide group as functional group showed high reactivity and complete binding of the diketones. The release of the ketones from the polymer PAH and thus the cleavage of the hydrazone required a hydrolysis reaction. For the subsequent photometric analysis, the diketones had to be stained due to their low absorption and low concentration. Based on the necessary parameters, a novel staining for diketones was developed using 2,3-diaminophenazine.

Two practice-oriented enrichment modules were tested using a polymer-filled capillary or a filled syringe filter. Comparative measurements showed the high accuracy and reproducibility of the process. Finally, a portable demo setup was developed, based on a portable photometer, which did not require an external power supply and could be used to perform measurements directly on-site. The portable system provided fast results with a high accuracy.