Decomposing the molecular complexity of brewing

Abstract

The compositional space of a set of 120 diverse beer samples was profiled by rapid flow-injection analysis (FIA) Fourier transform ion cyclotron mass spectrometry (FTICR-MS). By the unrivaled mass resolution, it was possible to uncover and assign compositional information to thousands of yet unknown metabolites in the beer matrix. The application of several statistical models enabled the assignment of different molecular pattern to certain beer attributes such as the beer type, the way of adding hops and the grain used. The dedicated van Krevelen diagrams and mass difference networks displayed the structural connectivity of the annotated sum formulae. Thereby it was possible to provide a base of knowledge of the beer metabolome far above database-dependent annotations. Typical metabolic signatures for beer types, which reflect differences in ingredients and ways of brewing, could be extracted. Besides, the complexity of isomeric compounds, initially profiled as single mass values in fast FIA-FTICR-MS, was resolved by selective UHPLC-ToF-MS 2 analysis. Thereby structural hypotheses based on FTICR's sum formulae could be confirmed. Benzoxazinoid hexosides deriving from the wheat's secondary metabolism were uncovered as suitable marker substances for the use of whole wheat grains, in contrast to merely wheat starch or barley. Furthermore, it was possible to describe Hydroxymethoxybenzoxazinone(HMBOA)-hexosesulfate as a hitherto unknown phytoanticipin derivative in wheat containing beers. These findings raise the potential of ultrahigh resolution mass spectrometry for rapid quality control and inspection purposes as well as deep metabolic profiling, profound search for distinct hidden metabolites and classification of archeological beer samples.

On the Trail of the German Purity Law: Distinguishing the Metabolic Signatures of Wheat, Corn and Rice in Beer

“…Such compounds that show strong evidence for the use of wheat (Pihlava and Kurtelius, 2016;Pieczonka et al, 2020) and corn (Fenz, 1991;Fenz et al, 1992) in brewing have been adequately described and have been confirmed in our study. In addition, numerous derivatives of these compounds could be characterized.…”

“…As reported before (Pieczonka et al, 2020) reinforces the presence of a carboxylic acid group of these compounds on the molecular structure level. Based on this annotation, known to be specific for the use of corn (Fenz, 1991) changes equivalent to hydroxylation, hydrogenation, methoxylation or water addition form a network of masses specific to corn.…”

“…In addition, numerous derivatives of these compounds could be characterized. Of particular note are the sulfate derivatives, some of which we already reported (Pieczonka et al, 2020). Little is known about the biological function of these compounds, but their function as polar regulation or storage conjugates can be assumed.…”

“…High-resolution mass spectra were acquired on a Bruker solariX Ion Cyclotron Resonance Fourier Transform Mass Spectrometer (Bruker Daltonics GmbH, Bremen, Germany) equipped with a 12 T superconducting magnet (Magnex Scientific Inc., Yarton, GB) and a APOLO II ESI source (BrukerDaltonics GmbH, Bremen, Germany) operated in negative ionization mode. The sample preparation, measurement and data processing parameters were chosen as reported recently ( Pieczonka et al, 2020 ; Pieczonka SA. et al, 2021 ).…”

“…The technical advances in separation methods, detector units and mass analyzers, as well as the further development of data collection and analysis, are showing new perspectives for modern beer analysis ( Pieczonka S. A. et al, 2021 ). The entire molecular diversity of beer can be shown and the influence of different raw materials such as hops and wheat on its metabolome can be captured ( Pieczonka et al, 2020 ). Complex reaction networks during the brewing process can be described ( Pieczonka SA.…”