Yeast & Fermentation

Is Alsatian beer top-fermented or bottom-fermented? The region's big names brew pale lager, and lager is bottom-fermented. The yeast works cool, at around 8 to 12 degrees Celsius, and settles to the bottom after fermentation. Top-fermenting yeast, by contrast, stays on top and ferments at room temperature.

Lager yeast is called Saccharomyces pastorianus, a hybrid of two species: ordinary brewer's yeast Saccharomyces cerevisiae and Saccharomyces eubayanus, first described in Patagonia in 2011. A pure culture of it was achieved in 1883 by the Dane Emil Christian Hansen in Copenhagen. Before that, brewers worked with mixed yeasts from their own operations.

Why does lager taste so clean? Because cool fermentation produces few fruity esters—the aromatic compounds reminiscent of banana or pear. This gives the beer a clear, calm character, letting the hops shine through more clearly. That's exactly what brewers aiming to showcase Strisselspalt are after.

After primary fermentation, which usually takes about a week, the young beer goes into lagering tanks. There it matures for several weeks at just a few degrees above freezing, until it turns round and clear. This is one reason why lager needs time and space, and why the breweries on the outskirts of Strasbourg were able to build on a large scale.

The small breweries around the region, in places like Lobsann, Riquewihr, Saales, or Schiltigheim, represent a distinct range of their own. Au Brasseur in Strasbourg reopened in 1991, and Brasserie Perle is a newer name in the city.