Research on yeast can untap new lager beer flavours
Lager is the most widely consumed style of beer, dominating the world market. But lager flavours and aromas are strongly limited. This is because the yeast strains used for brewing lager are genetically nearly identical. In a new study, scientists from the University of Santiago (Chile) and Stockholm University created new yeast strains that could revolutionize the lager beer industry by offering new and exciting flavours and aromas.
Lager yeast has barely changed for the last 500 years since it was first put to work by brewers in medieval Germany. What the old beermakers didn’t know, living in a world before microscopy and certainly long before modern day genomics, is that the microbe they were using was a hybrid cross between two species of yeast. This hybrid happily converted sugars into alcohol and carbon dioxide, but at much chillier temperatures (approx. 10°C) than the ale-yeast the brewers were used to. Today we know that all lager yeasts are hybrids between the ale yeast Saccharomyces cerevisiae and the cold-loving, wild species Saccharomyces eubayanus, which was not yet domesticated for the beer market, but had somehow snuck into the brewer’s fermentation vessels.
Researchers Jennifer Molinet (Stockholm University), Francisco Cubillos (University of Santiago), Rike Stelkens (Stockholm University) and their colleagues have created new lager hybrids. The study is published in PLOS Genetics and has been highlighted in international media outlets including The Economist and The Washington Post.
Wild yeast from the forests of Patagonia
The research team took a wild S. eubayanus yeast growing on tree bark in the forests of Patagonia, in the far south of Chile. First, Jennifer Molinet was struck by the yeast’s ability to survive the cold, harsh climate of Tierra del Fuego, the region’s gateway to Antarctica. Then, the researchers crossed the wild, cold-adapted yeast with a commercial ale yeast strain, and evolved the new hybrid in beer wort for 250 generations under chilled conditions, typical for lager brewing. Over the course of this experimental evolution, genetic mutations happened in the hybrid yeast genome that not only improved the speed of fermentation and resulted in higher alcohol production, but also produced unique aromatic profiles. “The new lager tastes spicy with hints of clove,” says Jennifer Molinet.
Faster fermentation and higher alcohol content
The researchers found that the faster fermentation and higher alcohol content is due to mutations in a metabolic pathway, allowing the hybrid to consume the sugar in the beer wort much more efficiently than its ancestors that did not have the mutations. The success of this new lager yeast is also due to the fact that it inherited the mitochondria (the main energy-producing organelle in the cell) from the cold-tolerant yeast from Patagonia.
Great potential to be untapped
There are many yeasts found in wild environments, in the forests of Patagonia, but also elsewhere in the world, which may be suitable for industry. But their potential has yet to be untapped.
“We hope that our research will help diversify the lager beer market. We think our approach, to expand the genetic diversity of the lager yeast through hybridization with wild strains, is a very promising avenue. We are excited to open a new door that can lead to new and exciting flavours and aromas,” says Rike Stelkens.
Francisco Cubillos and his team have already produced 500 liters of lager with the new hybrid strain, in collaboration with an artisanal brewery in Chile.
Read the study: Wild Patagonian yeast improve the evolutionary potential of novel interspecific hybrid strains for lager brewing in Plos Genetics.
Read more about Stelkens Lab
Read article: Yeast – teaching us how to cope with environmental change
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Rike Stelkens is a Wallenberg Academy Fellow and the research is partly funded by Knut and Alice Wallenberg Foundation.
Last updated: August 21, 2024
Source: Communications Office