LAUSR

Fluorochromes can impair analysis results or, due to their natural frequency (molecular vibrations) completely superimpose important signals and make measurements impossible. This is especially true for non-invasive, optical measuring methods such as Raman microspectroscopy, which reach their limits when fluorochromes are present. Beer contains many fluorescent substances, e.g., amino acids, vitamins and phenolic compounds. Therefore, in this study, eight different beers (lager beer, dark lager, Pilsner beer, Radler beer, wheat beer, dark wheat beer, alcohol-free lager beer, and alcohol-free wheat beer) were examined for their fluorescent ingredients. Using the PARAFAC model, the fluorescence of the eight beers could be explained for three components. By comparing with existing database literature, these components could be qualitatively assigned to the organic substances DOM (dissolved organic matter), DOC (dissolved organic carbon) or CDOM (colored dissolved organic matter) and OC (organic matter). The emission and extinction spectra helped to establish these organic substances as the three aromatic amino acids phenylalanine, tryptophan and tyrosine, iso-α-acid, phenolic compounds and the vitamin B group. In addition, correlations with the fluorescence intensities from the EEM (excitation–emission matrix) data were detected in combination with beer analyses. A correlation between the fluorescence intensity of origin and iso-α-acid could therefore be shown. The fluorescent amino acids phenylalanine, tryptophan and tyrosine showed only slight correlations with the fluorescent intensity. The calculated data showed that fluorescence spectroscopy with the obtained EEM represents a powerful real-time measurement, which offers sensitive monitoring for the identification of fluorescent substances in beer samples. Qualitative analysis combined with the PARAFAC analysis is also advantageous to identify the main components.