Archeochemistry of a Historical Beer Sample
A historical beer, dated to the German Empire era, was recently found in Lübbecke, northern Germany. The location of the find and label reconstructions link it to a local brewery that had a contractually agreed collaboration with a shipping company at the time (1885). Corked, wired and sealed, over 300,000 beers each year were shipped around the world. However, one of the beers brewed for export purposes has never left mainland Germany. This beer’s chemical composition represents a unique source of insights into brewing culture of the late 19th century when pioneer innovations laid the foundations for industrial brewing. Archeochemical analysis was used to investigate whether biological and molecular signatures can still be found for a brewing process that dates back to a time when metabolic pathways, modern food hygiene (Pasteur), industrial filtration (Enzinger), cultured yeast (Hansen) and the ‘refrigeration apparatus’ (Linde) were newly discovered and developed. Complementary analytics including metabolomics (FT-ICR-MS, LC-ToF-MS, TQ-MS/MS and 2D-NMR), microbiological, sensory, and beer attribute analysis revealed the beer’s chemical profile. The historical brewing process and the changes caused by aging could be described on a molecular level in more detail. Molecular networking revealed a hitherto unknown diversity of oxidized hops bitter acid derivatives that comes with natural decades-long ageing. The chemistry happening in such a sealed 0.75-liter micro laboratory resulted in numerous lipid oxidation products and undescribed high concentrations of Maillard reaction marker molecules (HMF, furfural). The clear indicators of the ravages of time, however, have not been able to obscure the detailed molecular information of the brewing of the late 19th century. Metabolomics certified the unprecedented good storage condition even after 130 years in the bottle. The beer’s original nature was unchanged in many parts. Comparing its chemical signature to that of four hundred modern brews allowed to describe molecular fingerprints, teaching us about technological aspects of historical beer brewing.
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