For the average beer drinker, the distinction between an ale and a lager boils down to how a beer looks, smells, and preferences. Ales tend to be fruity estery, while lagers are clean tasting and often described as Crisp. But to a brewer, the distinction is more essential than that.

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It’s not color, or flavor, or aroma, or hop\/grain\/malt varietals or even water hardness that separates a lager from an ale. To put it simply, lagers use an entirely different kind of yeast during fermentation. You’ll hear some beer pedants characterize the difference as Top fermenting vs. Bottom fermenting yeast, which is usually accurate, but useless to those who’ve no interest or experience with brewing.

Lager yeast, Saccharomyces pastorianus, was initially separated and explained in 1904 from the Danish mycologist Emil Christian Hansen while working at the Carlsberg brewery in Denmark. The two of these have since been discovered to be the same yeast, now called from the earliest name given, S.It possesses several parallels to the fact the fact the fact that of ale yeast, Saccharomyces cerevisiae – it in reality has entire stretches which are indistinguishable to S. Cerevisiae. Lager yeast behaves in a deeply different way than ale yeast. The most obvious distinction is that lager yeast is most effective in cold weather – conditions that will make an ale yeast go dormant.

Further, unlike ale yeast, no Wild kind lager yeast has ever been present in Europe and lager yeast need people to keep up its distribution. Lastly, ale yeast normally spends its life as a diploid organism. Lager yeast is what scientists call Allotetraploid: it has four copies of its genome, which is made up of genomes from two distinct species. Where the hell did lager yeast S. Pastorianus come from? And why did it only show up in the 1500 s, 1000’s of years after humans found out how to brew with S.

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Cerevisiae? The answer came in the year 2011, with the publication of Microbe domestication and the id of the wild genetic inventory of lager brewing yeast from Libkind et al in Proceedings of the National Academies of Sciences. In it, the scientists examined 6 yeast genomes: S. Cerevisiae, two species Saccharomyces species found in breweries, S. After obtaining samples from woods all around the globe, they separated two cold tolerant yeast strains from the woods of Patagonia in Argentina. After examining the genomes of those cold resistant strains, the researchers found that they were members of a new species of Saccharomyces yeast, that they named Saccharomyces eubayanus. It’s a domesticated hybrid strain of this Patagonian yeast.

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