Of all the varieties of beer that exist, lager is probably the most
maligned by craft beer aficionados. Mass market lagers are criticised
for their uniformity and bland fizziness; microbrewed ones are almost
nonexistent because lager is expensive to brew. The bulk of the lagers
on the market in Australia conform to a very narrow range of the style:
pale lagers rather than the traditionally German dunkels, märzens or schwarzbiers.
It is the international style that now dominates the local brews and faux
imports alike. They’re crisp, unvarying and unchallenging.
The strains of yeast used to brew a lager thrive at low
temperatures, generally between 7 and 15 degrees celcius. Brewing away
at lower temperature causes yeasts to grow more slowly. Traditional
lagers like marzen (which means “March” in German) were stashed in cool
caves in March and disgorged from the casks for Oktoberfest. It is a
costly process to replicate because of the need to keep the beer stored
at a low temperature while the yeast eats its way through the sugars
in the beer.
Lagers have been brewed in Germany since the 1400s but one of the
mysteries behind the beer is how did the particular strain of lager
yeast get to Germany. This year, we came one step closer to finding out.
Geneticists have known since the 1980s that the yeast brewers use
to make lager, S. pastorianus, was a hybrid of two yeast
species: S. cerevisiae — used to make ales, wine and bread —
and some other, unidentified organism.
Searching through collections of wild yeasts from Europe,
researchers — including Hittinger and his collaborators — tried to
identify lager's missing link but again and again were stumped. "There
were a few candidates, but none fit particularly well," Hittinger said.
So he and his colleagues began "sampling more systematically,"
collecting soil and bark, sap and abnormal growths called galls from
trees on five continents.
Team member Diego Libkind of the Institute for Biodiversity and
Environment Research in Bariloche, Argentina, found S. eubayanus in
galls on southern beech trees in Patagonia. The galls were
particularly rich in sugar, which yeast like to colonize and consume.
Patagonian natives used to make a fermented beverage from the
galls — a definite clue that the scientists were on the right track,
When the team brought the yeast to a lab at the University of
Colorado and analyzed its genome, they discovered that it was 99.5%
identical to the non-ale portion of the S. pastorianus genome,
suggesting it was indeed lager yeast's long-lost ancestor.
What makes this fascinating for one of the world’s more boring beers
is that somehow, the yeast from Patagonia has made its way from the
Americas to Germany in the early 1400s. There is a possibility that the
bacteria existed in an as yet undiscovered location in Europe, but the
first European to make that passage was Christopher Columbus in 1492.
The small unknown in history suddenly makes lager look a little more