Yeast, the essential microorganism for fermentation in the brewing of beer, converts carbohydrates into alcohol and other products that influence appearance, aroma, and taste. In a study published online today in Genome Research (www.genome.org), researchers have identified the genomic origins of the lager yeast Saccharomyces pastorianus, which could help brewers to better control the brewing process.
Very nice. Ale yeast, the ‘original’ is a top fermenting yeast, while lager is a bottom-fermenting. Because of these characteristics, lagers are more easily produced for mass consumption but usually do not have the taste complexities found in ales. ALes can also be easily produced at room temperatures while lagers need cooler temps.
This looks like an interesting report, with the mystery of where lager yeast came from being closer to a solution. What I found really interesting is that the yeast from different breweries looked like they had been under selective pressure for that specific brewery.
So it may not just be the water that makes the same brand of beer produced at different sites to taste differently. The yeast may actually be diverging at the two sites.