Berliner Weisse is a beer style originating from the region around Berlin, Germany, which developed gradually from the 17th to the 20th century. Its main characteristic is a mild sourness and tartness with a light and fruity character, which led to the nickname “Champagne of the North.”
The origins of Berliner weisse are murky at best. There are several competing theories surrounding the development of the style. One theory holds that the Huguenots, French immigrants to Berlin in the early 18th century, developed the beer after migrating through Flanders and picking up techniques from brewers of Flanders brown and red ales.
What we do know is that wheat beers brewed around Berlin were not originally sour but rather light and easy to drink compared to the heavier brown beers. Most of the beers were about 3% ABV and used a mash of approximately 50% barley and 50% wheat. Interestingly, the wort was not boiled and the amount of hops used was quite low. Given that the wort was not boiled, the hops were not typically added in the kettle. Instead, hops were boiled with water (concurrent with the mashing process) and then this boiled hop infusion was blended into the mash to increase the mash temperature. This was a version of an infusion mash, one which may have allowed early brewers to achieve different mash temperatures without decoction.
With no wort boiled to effect sterilization, one can easily imagine the huge diversity of microorganisms that survived into the cooled wort. It was necessary to start the fermentation quickly enough to suppress most of the spoiling organisms. Even so, heat-tolerant lactic acid bacteria survived and synergistically fermented the worts into beers with a dry and lightly acidic character. This was not true spontaneous fermentation as is carried out in lambic beers—yeast was pitched, but carried both yeast and bacteria from previous fermentations. Other organisms survived wort production; malt has plenty of its own lactic bacteria. Fermentation took place in wood (and wood, being porous, is difficult to sanitize).
We can therefore differentiate between three production steps where acidification could have taken place:
The result was a range of beers with vastly differing levels of acidity, and although acidity was not uncommon in beers of the 17th and 18th centuries, the variability of the beer meant that it often failed to meet a consumer’s expectations.
The modern Berliner weisse developed relatively late, during the 19th century, and numerous Berlin breweries specialized in its production until the style started to wane in the 1950s. The technology applied in these breweries was very similar to the brewing process in earlier times, with the main difference being that fermentation was better controlled, especially with respect to the ratio of yeast and lactic acid bacteria during fermentation and lagering (the average bacteria concentration was approximately 20% of the yeast concentration).
Berliner weisse has not always been a low-gravity beer. Some were brewed at normal gravities, then either consumed straight or watered down at the beer hall, either by the house or by the consumer. To cut the varying acidity levels, the addition of various syrups became popular over the years, with the most common being bright green woodruff syrup or bright red raspberry syrup.
At the height of its popularity in the 19th century, Berliner weisse was the most popular alcoholic drink in Berlin, with almost 700 breweries producing it. But the intervening years have not been kind to Berliner weisse. Within Europe, it enjoys protection as a sort of appellation controlee; Berliner weisse can only be produced within the city limits of Berlin. That honor, however, has not saved it, and it has become a rare specialty, produced by only two full-scale commercial breweries, Berliner Kindl and Schultheiss. These breweries no longer use a yeast/bacterial blend to ferment the beer; the bacterial fermentation is conducted separately and the beer is blended for a defined acidity. The beers are very pale, slightly hazy, and effervescent, with a light tang. They are refreshing oddities but show little complexity.
In the last few years, however, Berliner weisse has enjoyed a revival among artisanal brewers. Small experimental brews have been conducted in Germany, and the resulting beer found to be very fine and complex, with no need for any syrups. American craft brewers have also taken to producing Berliner weisse, which is taking its place within the nascent culture surrounding sour beer styles. Even though the United States is far from Berlin and its appellation controlee, it is the place where production and enjoyment of this compelling old beer style is likely to flourish in the future.