Irish scientists have helped uncover the origin of lager beer - which may have come about due to the death of a childless German nobleman.
A team from University College Cork and the Technical University of Munich in Germany, combining historical research with science, believe that the yeast used for the world's most popular beer - Saccharomyces pastorianus - came about as a result of mating two different yeast species - a Bohemian S. cerevisiae and a Bavarian S. eubayanus in Munich at the start of the 17th century.
The Bavarian brewing ordnance of 1516 - regulations limiting the ingredients in beer - stipulated that only bottom fermentation species of yeast were permitted.
But in 1548 the powerful nobleman Hans VI von Degenberg was granted a dispensation to allow the brewing of wheat beer through top fermentation.
However when Hans VIII Sigmund von Degenberg, the grandson of Hans VI, died without an heir in 1602, his property and assets- including the family brewery at Schwarzach in Bavaria - were seized by Maximilian I, Duke of Bavaria.
Historical records show that on 24 October 1602, top-fermenting yeast were brought from Schwarzach to the Duke’s brewery in Munich, where the brewing of wheat beer then alternated with the traditional Bavarian brown beer.
Writing in the journal FEMS Yeast Research, the research authors propose that by the time a dedicated wheat beer brewery had opened in 1607, top-fermenting wheat beer yeasts from Schwarzach and bottom-fermenting yeasts from the Munich brewery had mated to create a brand new species that we now know as the lager yeast.
Co-author of the research, Professor John Morrissey of UCC’s School of Microbiology, said: "We often think historical events are almost pre-programmed, but this is an amazing example of how chance events – the lack of an heir, the Duke’s thirst for wheat beer, and the unorthodox sex between different yeasts, culminated in a new yeast species that changed the world of beer."
