Berliner Weisse is a beer that is integral to the German capital’s identity, and in particular that of its historical working-class culture. It is a sour beer like the Belgian geuze and lambic, or the gose brewed in Leipzig, Germany. Traditionally, Berliner Weisse was made with top-fermenting yeast, lactic-acid fermentation and subsequent bottle fermentation. It used to be served in special wheat beer pubs that took advantage of the fact that sour beers can be stored for decades in the bottle and that their flavors change over time, not unlike wine. Pubs could thus offer a selection of fresh and bottled, aged wheat beers.
The light beer is brewed with barley and wheat malt and fermented using a mixed culture of the top-fermenting yeast Saccharomyces cerevisiae and lactic-acid bacteria, mainly Lactobacillus brevis, and the secondary fermentation yeast Brettanomyces bruxellensis that ensures a higher degree of bottle fermentation. Wheat beer breweries traditionally produced wheat beers exclusively to avoid the risk of contaminating other beers with lactic-acid bacteria, which would have influenced their flavor in an undesirable manner.
In 1905, there were 51 wheat beer breweries in Berlin. Ten were still in operation in 1940, but the number recently shrank to a single brewery that only produces an industrial variant of Berliner Weisse without bottle fermentation. The lack of bottle fermentation results in less acetic acid and a lower CO2 content that must be compensated by subsequent carbonation. The sour flavor of industrially brewed Berliner Weisse cannot hide the lack of bouquet that would otherwise develop during aging in the bottle. In recent years, breweries in the Berlin craft beer scene have revived the traditional Berliner Weisse brewing technique.
The light, bright, low-alcohol (approx. 2.2% to 2.7%) but highly carbonated draft beer is characterized by its mild, somewhat sour flavor, light malt body and fruity aroma. Other wheat beers are usually much more highly hopped than the slightly bitter Berliner Weisse, in which the hops aromas are barely noticeable. Fruit syrup is added to mask the pronounced sour taste of industrially brewed Weisse. Traditional mixtures with caraway and bitter orange liqueur have been documented.