Fig. 4: Hierarchical clustering arranges the beer samples’ FTICR mass spectra with regard to their beer type.

Color code of the observed clusters: lager beer blue; beer brewed with special grain red; wheat beer green; craft beer yellow; alcohol-free beer light blue. The cluster of QC lager beer samples is framed. The enlarged excerpt shows the cluster of one brewing site’s alcohol containing and alcohol-free beers. The samples’ order is stated below.