It’s unusual in several respects, for a German beer. For a start it’s spontaneously fermented, a technique that mostly died out in Germany a couple of centuries earlier. Then there’s the ridiculously high OG and equally ridiculously high FG. Not to mention the organism that performed the fermentation.
And on that latter point Olberg has made things much clearer. I’ve read descriptions of a slime forming on the top of the beer. Olberg’s explanation of what was doing the fermenting explains that observation.
Off with the paraphrase.
Jopenbier can be considered a type of hopped malt drink. The mashing method employed doesn’t really matter that much. So for reasons of economy a short mashing scheme is usually employed. Per 1500 kg malt 25 to 30 pounds of hops are used. The wort is left to cool in the cooler and then run into fermenting tuns, which hold between one and two barrels. The tuns are 1 to 2 metres tall and built much narrower than usual. The wort remains in the tuns until after about three weeks it begins to ferment all on its own as aa result of spores that have fallen into it. No great value is placed on cleanliness or cleaning in the fermentation cellar, only the cellar floor is kept clean. Though naturally the cellar is kept dry and well ventilated. If I’m not mistaken the spontaneous fermentation is caused by Penicilium glaubum though Saccharomyces Beylink is also present. The fermentation is very violent which is why the tuns are kept closed with the exception of a vent under which a vessel is placed to catch overflowing liquid. When fermentation is complete the tuns are uncovered and the beer left to rest until it is shipped. Before it is filled into the smallest transport casks it is passed through filter sacks. The alcohol content is 3.5% and the acidity (measured in acetic acid) is 0.95%.
Source: Olberg, Johannes (1927) Danziger Jopenbier in Moderne Braumethoden, pp 65-66, A. Hartleben, Wien & Leipzig.
The penicillin will explain the mould, I guess. Unfortunately a search for that particular type threw up nothing whatsoever. It’s probably something that has changed its scientific name over the years. The same with the Saccharomyces – a total blank. Please let me know if you have any idea what they might be.
Interesting that it was fermented in tall narrow vessels. And counterintuitive. Surely if you’re relying on shit dropping into the wort to ferment it you’d want as large a surface area as possible?
That level of acetic acid would result in a pretty sour beer. Though with that amount of residual sweetness, it was probably barely noticeable. That will be 3.5% ABW, by the way.
Here’s the only analysis of Danziger Jopenbier I have:
|"Jahresbericht über die Leistungen der chemischen Technologie (1907)", 1907, pages 352 - 353.|
The FG is higher than the highest OG I’ve ever seen for a UK-brewed beer. Though the ABV is high enough for Jopenbier to count as an alcoholic drink, Doubt anyone could drink enough of the treacle to get pissed, mind.