Lager beer diversity

Research is sometimes triggered by the strangest things. Some newly published research e.g. originated during a Friday evening beer tasting at a lab of the University of  Leuven, Belgium. On a regular basis students taste and discuss five or six related beers. 

One night, we tasted six Pilsner-type beers, and someone commented on how similar they were, much more so than beers of other types.

Unlike ales, lager beers (such as the Pilsner-type) differ little in flavor. Lager beers are fermented with Saccharomyces pastorianus, which is a hybrid cross of Saccharomyces cerevisiae and Saccharomyces eubayanus, at temperatures generally between 8 - 15 C. They also have a lower alcohol content, 4 - 5.5 vol%. Ales are fermented by Saccharomyces cerevisiae, at higher temperatures- usually between 15 - 25 C., and they tend to be stronger than lagers.

The researchers didn't leave it at that and did what every good scientist does. They developed some hypotheses and put them to the test. Their assumption was that if they could create more crosses between Saccharomyces cerevisiae and Saccharomyces eubayanus, they would perhaps produce a set of more diverse lager yeasts, which in turn could yield more diverse lager beers. Problem is that both yeast species are very different from each other and the researchers had to do a lot to optimize growing conditions, hoping to facilitate mating between the yeasts. To this end, they experimented with different temperatures and growing media.

We were able to get some serious sexual action between our yeasts, which resulted in hundreds of new lager yeast strain. 

But of 31 new strains that they tested in small scale beer fermentations, only ten performed reasonably well in terms of speed of fermentation, and flavor. Some were really bad according to the testers. The best four were subsequently tested in full scale fermentation. 

Two were magnificent,they fermented more quickly than the commercially used reference lager yeast that we compared them to, and they produced really nice flavors.

We found that the different lager yeasts that we created showed very different aroma profiles compared to today’s commercially available lager yeasts. This means that it now becomes possible to make lager beers that, like ale beers, are more different from each other, and this without the need to extensively change the production process.

That's what I would call curiosity-driven science.