New diversity for lager beers

September 25, 2015

Unlike ales, lager beers differ little in flavor. But now, by creating new crosses among the relevant yeasts, Kevin Verstrepen, PhD, Stijn Mertens, and their collaborators have opened up new horizons of taste. The research is published in the September 25 Applied and Environmental Microbiology, a journal of the American Society for Microbiology.

The relative uniformity of flavor among lagers turned out to result in significant part from a lack of genetic diversity among the yeasts. Genetic studies showed that lager yeasts had resulted from just two crosses between the parent yeasts, Saccharomyces cerevisiae, and S. eubayanus. The problem was that the two yeast species are so different—like lions and tigers—as to make successful crosses rare.

"We figured that if we could create more crosses between S. cerevisiae and S. eubayanus, we would perhaps produce a set of more diverse lager yeasts, which could yield more diverse lager beers," said Verstrepen, who is Professor in Genetics and Genomics, University of Leuven and director of the VIB lab for Systems Biology, Leuven, Belgium. The researchers did their best to optimize growing conditions, hoping to encourage 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 strains," said Verstrepen. 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," Verstrepen confesses.

They then tested the four best of these in full scale fermentations. "Two were magnificent," said Verstrepen. "They fermented more quickly than the commercially used reference lager yeast that we compared them to, and they produced really nice flavors."

More generally, "We found that the different lager yeasts that we created showed very different aroma profiles compared to today's commercially available lager yeasts," said Mertens, who was the paper's lead author. "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."

Lager beers are fermented with S. pastorianus, which is a hybrid between S. cerevisiae and S. eubayanus, at temperatures generally between 8-15oC. They also have a lower alcohol content, 4-5.5 percent by volume. Ales are fermented by S. cerevisiae, at higher temperatures—usually between 15-25oC., and they tend to be stronger than lagers.

The research originated during one of the regular Friday evening beer tastings at the laboratory, in which students would 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," said Verstrepen.

Explore further: Thanks, fruit flies, for that pleasing beer scent

Related Stories

Thanks, fruit flies, for that pleasing beer scent

October 9, 2014

The familiar smell of beer is due in part to aroma compounds produced by common brewer's yeast. Now, researchers reporting in the Cell Press journal Cell Reports on October 9th have discovered why the yeast (formally known ...

Lager yeast ancestors were full of eastern promise

February 26, 2015

There are few drinks as iconic as a 'pint of the black stuff'. It might, therefore, surprise beer connoisseurs to learn that the DNA of the all-important brewing yeast – the building blocks of the perfect Stout – is the ...

Better chocolate with microbes

July 15, 2015

For decades, researchers have worked to improve cacao fermentation by controlling the microbes involved. Now, to their surprise, a team of Belgian researchers has discovered that the same species of yeast used in production ...

The evolution of beer

August 11, 2015

From Austrian monks to American craft brewers, beer geeks are everywhere. But making a good beer not only depends on the best ingredients, but also the best yeast.

Researchers optimize cocoa fermentation process

August 14, 2015

The Barry Callebaut Group, VIB (Flanders Institute for Biotechnology) and KU Leuven (University of Leuven), with the support of IWT (Agency for Innovation by Science and Technology-Flanders), managed to improve the process ...

Recommended for you

Whiskers help animals sense the direction of the wind

August 24, 2016

Many animals appear to have an impressive ability to follow the wind to find food, avoid predators, and connect with potential mates. Until now, however, no study had examined how land mammals know the direction of the wind. ...

Scientists develop new techniques to track how cells develop

August 24, 2016

Understanding how various cell types differentiate themselves during development is one of the fundamental questions in developmental biology. Using genome-editing tools, Harvard scientists are getting closer to finding answers.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.