The 19th century witnessed many advances in scientific enzymology and microbiology that laid the foundations for modern biotechnological industries. In the current study, we analyze the content of original lager beer samples from the 1880s, 1890s and 1900s with emphasis on the carbohydrate content and composition. The historic samples include the oldest samples brewed with pure Saccharomyces carlsbergensis yeast strains. While no detailed record of beer pasteurization at the time is available, historic samples indicate a gradual improvement of bottled beer handling from the 1880s to the 1900s, with decreasing contamination by enzymatic and microbial activities over this time span. Samples are sufficiently well preserved to allow comparisons to present-day references, thus yielding molecular signatures of the effects of 20th century science on beer production. Opposite to rather stable carbohydrate profiles, some aldehydes reach up to 40-fold higher levels in the historic samples as compared to present-day references.