Over the past few years, cold IPA has introduced many brewers and drinkers to the idea of a non-lager beer style fermented with lager yeast. However, this is a familiar move that brewers have been using ever since lager yeast strains and bottom-fermentation techniques first spread from Bavaria in the 19th century. Whether for reasons of practicality or flavor profile, many styles commonly brewed with ale yeast have also been brewed with lager yeast by breweries all over the world.
Lager brewing took the world by storm starting in the mid-1800s, as the popularity of the golden pilseners from Bohemia spread, and as German brewers emigrated to other countries in search of new opportunities. With them they brought lager yeast (Saccharomyces pastorianus), a genetic hybrid of ale yeast (Saccharomyces cerevisiae) and the more cold-tolerant Saccharomyces eubayanus. This genetic hybrid—lager yeast—evolved via adaptation over the centuries in Bavaria to ferment at cooler temperatures and produce crisp, clear beers. That was in stark contrast to the relatively murky, tart, and/or funky ales that were ubiquitous in other brewing regions.
An Old Trick, Style by Style
As lager brewing became more popular, ale and porter brewers reacted to the new competition with beers such as cream ales—essentially, pale lagers made with ale yeast. That brings us to an example of where things got mixed up: Once this style became established with consumers, some brewers began making them by blending beers made with ale and lager yeast. Others who were used to brewing lagers also wanted in on this trendy style—so they simply brewed it with lager yeast.