It’s lager, but not as we know it. One of the world’s most popular beer varieties could soon be made with a range of novel flavours, thanks to new hybrid strains of yeasts used in brewing.
“We are in the process of generating an entirely new set of strains that has the potential to significantly diversify the current lager experience,” says at the Millennium Institute for Integrative Biology in Santiago, Chile. “It is our hope that in the future, producers will be inclined to explore and innovate with these novel lager yeasts, enriching the brewing landscape.”
Most other types of beer are made with ordinary brewer’s yeast (Saccharomyces cerevisiae). But lagers are made with a hybrid of S. cerevisiae and Saccharomyces eubayanus, named Saccharomyces pastorianus. That hybridisation is thought to have happened on two occasions in the past 500 years, most likely in the breweries of Northern Europe. This means that all lager yeasts originate from just these two lineages – known in the industry as the Saaz and Frohberg strains.
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These lager yeasts metabolise more slowly and in much colder conditions than ale yeasts, giving lager its famously clean and crisp taste. Ale yeast, on the other hand, has hundreds of distinct varieties all over the world, and this helps to create a much wider range of flavours.
The origin of the lager yeast ancestor S. eubayanusĚýhas long been mysterious, but in 2011, wild strains were found in the Patagonian Andes. Cubillos and his colleagues brought these wild strains back to the lab to hybridise them with S. cerevisiae.
The team subjected the hybrids to conditions typical of beer fermentation and examined which hybrid strains performed best in terms of fermentation and flavours. Within six months of lab-accelerated evolution, the researchers had a shortlist of new lager yeast candidates.
Cubillos says beers made with these strains have different aromas and tastes compared with existing lagers. “They combine different profiles from both species, including fruity esters from both species and some light phenol notes from S. eubayanus,” he says. “Interestingly, there is so much diversity in these two species that many novel profiles could be obtained in the future.”
at the University of Queensland, Australia, who has collaborated with Cubillos’s team in the past, says it is an interesting idea to find the wild ancestors of yeasts used in lager and try to recreate the hybridisation that happened accidentally centuries ago.
“There’s a massive diversity of wild yeasts in the environment,” says Schulz. “It’s actually hard to know yet whether these yeasts will be able to produce different-flavoured beers, but I’m very excited to try them.”
at KU Leuven, Belgium, says the study furthers the understanding of hybrids between the ancestors of lager yeast and serves as a stepping stone towards commercial applications.
In 2015, Verstrepen and his colleagues by crossing six different S. cerevisiae strains with two different S. eubayanus yeasts. The resulting hybrids were found to yield very different lager beers, he says.
“Many strains did not yield palatable beer, though – but a few did, and one of them is now used commercially at massive scales,” says Verstrepen.
bioRxiv
