Brewing Production investigated by 1H NMR Metabolomics on samples from Finnish American IPA and Sweet Stout Beers

This study has characterized beer samples taken from two different Finnish beer: Claudia’s Citra Stout (Mustialan Kartano Panimo) and Thunder Chief (Hopping Brewsters Panimo). Both of them have been analyzed from several steps of the brewing process, in order to characterize the final product (4.) and the metabolites change (1. after mashing, 2. after Whirlpool and 3. after secondary fermentation). The aim of this research was to discover how each compound changed during the beer making process, how this could be useful to characterize different styles of beers and if there was any by-product, in the liquids extract discarded, that could be valorized. The beermaking process has been followed from a metabolomics perspective, based on 1H NMR (Nuclear Magnetic Resonance) . In order to get a representative result, 33 NMR spectra have been analyzed, which we obtained by experimenting with different samples preparation methods [(a),(b),(c),(d)], to get the best characterization possible. The majority of the metabolites identified decreased in concentration from the steps before fermentation to post-secondary fermentation. In particular, it has been possible to distinguish 73 metabolites in unfiltered and unpasteurized beer (artigianal), and in commercial beer (Viktor), which has been used as reference. All of them were different in quantitative terms and through their characterization it was possible to identify exactly their presence in others beer samples. Furthermore was possible to obtain an objective opinion on the specific molecules and metabolisms acting on them, in order to optimize a recipe or to modify one that presents problems. Just for this last purpose, it was useful to verify changes that occur during the main steps (1-2-3-4), in order to identify not only the problem, but also in which step this is presented, and consequently how to intervene.