New analysis of 1,000 year-old pottery fragments, unearthed in Argentina, has revealed the earliest known traces of the so-called “lost parent” yeast of lager beer.
According to a report by NBC News, the genetic analysis of ceramics, excavated by archaeologist Dr Alberto Perez, shows that they contain traces of the cold-resistant yeast strain Saccharoymyces eubayanus, one of the ‘parents’ of the hybrid strain Saccharomyces pastorianus used in the production of lager.
Dr Perez uncovered the pottery fragments near San Martin de Los Andes in Argentina, close to the Chilean border, last year. The subsequent analysis that led to the discovery of S. eubayanus was conducted by an interdisciplinary team led by archaeologist Jose Luis Lanata and the biologist Christian Lopes, both based at Argentina’s National Scientific and Technical Research Council (CONICET).
These findings, if proven to be genuine and not the result of later contamination, could threaten lager’s supposed German origins. At the very least, they would demonstrate that the people of South America were producing alcoholic drinks using the S. eubayanus yeast strain around 400 years before the Europeans did.
Commenting on the results of the analysis, Dr Perez who is based at Universidad Catolica de Temuco in Chile, said: “This is the first archaeological evidence and earliest evidence of any kind of Saccharomyces eubayanus being used in alcohol production. Our findings confirm the historical presence of the yeast in this region and now we have confirmation of its use.”
“Saccharomyces eubayanus turned up in remains from two of the sites [out of 6 excavated]. We had strong evidence showing the ceramics had been used to ferment vegetal products to produce alcoholic beverages”.
Unlike ales, lager is usually fermented at cool temperatures and then cold-stored – the German word ‘lager’ translates as ‘storeroom’ or ‘warehouse’. The yeast strain most commonly used in lager production is Saccharomyces pastorianus. Since the 1980s, scientists have been aware that this yeast is in fact a hybrid with two ‘parent’ yeasts.
Before 2011, beer experts were only aware of one of the ‘parents’ – warm-brewing yeast Saccharomyces cerevisiae – and suspected that the other parent yeast, the one that allowed lager to be fermented at cold temperatures, was not native to Europe. In 2011, Dr Chris Hittinger from the University of Wisconsin-Madison along with a team of geneticists and microbiologists from the US, Portugal and Argentina discovered S. eubayanus in wild samples from a Nothofagus tree in Patagonian forests.
Although S. eubayanus’ presence in South America is known, this find is the first and earliest archaeological evidence of it being used to produce alcohol. Despite being native to America, it was believed that its use in the production of alcohol did not occur until the 15th century, with lager thought to have originated in Bavaria in the 1400s.
Scientists remain uncertain as to when the yeast strain found its way to Europe. The most recent study conducted by Dr Hittinger in 2016 suggested that birds or insects may have transported the yeast strain, possibly thousands of years before lager was produced in Germany.
“We discovered there were several strains of Saccharomyes eubayanus,” Dr Hittinger said. “Our research showed that Patagonia is home to a tremendous diversity of S. eubayanus and one of our models suggested a lager yeast ancestor originated there and spread northwards.”
Dr Hittinger, who was not part of Dr Perez’s team, added: “The evidence that Saccharomyces eubayanus may have been used to ferment beverages before contact between the Eastern and Western Hemispheres suggests an intriguing twist to the origin of lager yeasts.”
“Future genetic studies will be required to exclude the possibility that these strains are environmental contaminants and to determine how they are related to wild Patagonian strains, wild strains from the Northern Hemisphere, and the domesticated hybrid strains used to brew lagers”.
Perez added that the people that made the ceramic vessels containing the lager yeast “would have been from a hunter-gatherer society with a mixed economy based on seasonal produce of mainly seeds and fruits and some cultivated plants”.