HAVE you ever wondered why some types of lagers taste different from others? The answer, it seems, has a lot to do with the yeast.
Lagers belong to two main families: the Saaz group such as Carlsberg, brewed in Denmark; and the Frohberg lagers that include Heineken and Oranjeboom from the Netherlands.
To find out whether there is a genetic difference between these families, Gavin Sherlock and Barbara Dunn of Stanford University, California, compared the genes of 17 lager yeast strains across the world dating from between 1883 and 1976.
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It has long been thought that Saccharomyces pastorianus, the yeast used in lager production, formed only once from the hybridisation of S. cerevisiae and S. bayanus. Instead, the team discovered that it happened at least twice in two separate locations in Europe, giving rise to the two different lager families (Genome Research, ). The hybrid, which makes lager instead of ale, probably evolved in Bavarian beer-brewing cellars during the 16th century.
The team also found that Saaz yeasts have a single copy of each parent yeast’s genome, whereas the Frohberg yeasts have an extra copy from S. cerevisiae. They believe this difference affects the flavour of the lager, as well as how quickly the yeasts can ferment the malt.
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