RESEARCH & DEVELOPMENT
Traditional Beer
Berliner Weisse through the ages – part 2: a fine line between aroma and spoilage Dr. Peter Lietz, Berlin
In the 19th century, Berliner Weisse could be found all over Berlin. However in the last few decades, it has been reduced to a niche existence. Recently, craft brewers around the world have rediscovered this traditional style of beer. In the second part of his article, the author focuses on the creation of this sour, top fermented beer and the importance of microorganisms to the beer’s flavor and quality.
Sudhaus Landré (brewhouse) on Stralauer Strasse in Berlin (year unknown)
Originally, the heavily carbonated, only slightly acidic lagers of the 17th and 18th centuries were either brewed from 100 % wheat malt or with a proportion of barley malt at varying intensities. The acid was produced by acid-forming bacteria within a few days. This bacteria could enter into the process in different ways: in the malt, the water, or the air. Huguenot influence At that time, top fermentation was used exclusively. In addition to the brewing yeast Saccharomyces cere visiae, strains of wild yeast (Torula species) were involved in the process, as were lactic acid bacteria, usually in the form of contamination. Historical records do not precisely indicate the first time a sour weiss beer was produced. The first Berlin cookbook written by Johann Sigismund Elsholtz in 1682 is entitled Diateticon and supports the conclusion that a white beer was
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already being brewed in Berlin during the mid-17th century. One thing is certain, however: The Huguenot influence in Berlin is tied to how these white beers developed into what later became known as the typical Berliner Weisse. These religious refugees from France preferred the clear, lighter wheat beer produced in their own breweries; this beer contained approximately 5.7 % malt extract and a correspondingly low alcohol content of just under 2 %. The classic Berliner Weisse produced and marketed by specialized weiss beer breweries until the second half of the 20th century likely did not come into existence until the 19th century. Improper fermentation in the mashing process In the late 18th century, wort was prepared in a similar way to the method still used later on in the 19th century. One important difference should be mentioned, however. In the late 19 th century, brewers assumed that if they used unboiled mash, the cultured lactic acid bacteria would remain alive in the wort as part of the microflora in the malt. This was the only reason why they did not boil the mash and wort. It wasn’t until later that they realized that only a negligible amount of cultured lactic acid bacteria ended up in the wort – and, consequently, in the fermentation process – via the mashing process. However, this method also involved significant risk of serious contamination, particularly with unwanted Micrococci bacteria. Brewers attempted to avoid improper fermentation by
Brauerei Forum International – November 2019
increasing the mashing-off temperature to 85°C – and later, potential improper fermentation was countered by boiling the wort and using pure cultures. Lactic acid bacteria during fermentation In their work “Zur Kenntnis der stäbchenförmigen Milchsäurebakterien im Berliner Weißbier” (‘On Bacillar Lactic Acid Bacteria in Berlin Weiss Beer,’ 1909), Schönfeld and Dehnicke focused on the causes of different types of acidification. They isolated various lactic acid strains of the yeast species Saccharobacillus pastorianus from seven different breweries, then categorized these strains in three groups. During the weiss beer fermentation process, the lactic acid bacteria generally grew at a rate similar to yeast propagation; bacterial growth did not begin to slow until the beer reached an alcohol content of more than 5 %. The mashing process and hop addition had a significant impact. The propagating lactic acid bacteria and Pediococci had the least significant impact on the beer when hops was added to the mash. If the wort was boiled with hops, the mixture did not achieve the desired level of acidity. Apparently, the boiling process generated more antibacterial substances than boiling the mash with hops did. That’s why weiss beer brewers long shied away from boiling the lautered wort before casting and consequently risked the beer becoming ‘ropy.’ To reduce this risk of contamination, Schönfeld suggested heating the lauter wort to at least 85 °C before
