As my german sour beer research continues I found some really interesting facts about Gose.
From a newspaper article from 1882 there is the following:
„There is no yeast pitched into the beer. Due to that fact a thick layer of mold builds on top of it.
The thicker this leather like layer gets the better the stability of the beer. The reason for that is that the mold layer blocks oxygen from getting into the beer. Only when the beer is given away yeast is pitched.“
That Gose stems from spontaneous fermentation is nothing new but a leather like layer sounds quite interesting. There is also talk that a second fermentation took place in long necked bottles and the rising yeast makes a barrier so the beer could develop carbonation. But how would that work? I never hat brittle or dry Kräusen. The next bit of information comes from Jakob from the german homebrew forum:
„Wilhelm Henneberg first discovered 1897 the „Bacterium acetosum“ in the Dölnitzer Gose. It produces Acetic Acid and can be used for production of vinegar. According to my research it could be a polymer building bacterium that creates the barrier in the bottle.“
I try to translate one of the sources that describes the bacterium:
„Bacterium Acetosum Henneberg: The growing stuff (german word Auflagerung) on the streak cultures has a very fine divided border. When growing the same bacteria on a tryptone solution it results in a strong hazyness of the solution. The flower? (Kahmhaut i would translate to pellicle) on a sterile beer is smoth, firm and white. and shows only little ambition to climb the walls of the culture glas. Older pellicles have a peculiar convultion on their surface. The Zoogiöen (means something like group of bacteria) consists of cell chains, these chains are hard to separate from the groups. And after 2 day growth the links are 1 fi long and 0,4-0,8 fi wide. The pellicle stain iodine not blue. Hypotrophic, bloated, spindly cell forms appear when growing this Acetic acid formers on gose at a temperature of 30°C after two days. On lager beer these cultures are more seldom. At 36°C forms are created like hansen pictures them for B. Pasteurlanum. The Temperature optimum for B. Acetosum is at room temperature”
So interesting stuff.
He also Drops some nice Analysis from Gose around 1904 (I only post the relevant values):
|Name||Final Gravity||Alcohol (g/l)||Lactic Acid (g/l)||Salt (g/l)||Degree of Fermentation|
|Gose Jung Würze||1,0420||1,72||0,01||0,13||24,2|
|Gose Jung nach 48 Stunden||1,0178||3,86||0,12||0,17||60,4|
|Gose nach vier Tagen||1,0090||2,94||0,12||0,15||64,8|
|Gose Jung nach vier Wochen (sauer)||1,0110||3,64||0,73||0,15||65,6|
This is quite interesting since Berliner Weisse has way more lactic acid (around 2g/l) but gose was described the more acidic beer. This supports the theory that there was a acetic acid producing bacteria in the mixed culture / semi spontaneous environment (it was fermented open in attics).
Another nice information is that the Gose from Goslar did not contain coriander but used spruce branches for lautering and desinfecting. And if spiced Vermouth and Cinamon was used.
Analysis: “Armin Röhrig, W. Ludwig und H. Haupt: Gose. (Bericht der Chemischen Untersuchungsanstalt Leipzig 1904, 74.)