January 2025

Regular readers of our website will have noticed that the last brew report was almost two months ago. Sometimes we just don't manage to write anything during the lecture period, but of course we still have beer in our brewery. After all, what could be worse in the world than a brewery with no beer....
 

Nevertheless, we will no longer be reporting on every brew in detail in future, partly because the isothermal high-temperature mashing process we have developed is slowly gaining international recognition thanks to our recent publication in the Journal of the American Society of Brewing Chemists . Apart from exceptions resulting from the scientific approach, we are now brewing consistently according to this new brewing method and are also further optimizing the processes in the brewing plants. In the meantime, we have also found a way to achieve an alcohol content of just 2.5 % vol. with our BrewTools system (malt pipe technology) at a wort gravity of 11.5 °P (our regular target value), even if we are still 0.5 - 0.7 % vol. above the values achievable with stirrers.
A sensory evaluation of beers with different alcohol contents in a local student pub at the end of last year showed once again that it is not possible to reliably identify the moderate alcohol content of our beers, and for physical and chemical reasons alone, it makes little sense to assign the properties of a flavor carrier to alcohol in a diluted aqueous solution, and beer is nothing else. Nevertheless, beers above approx. 6% alcohol by volume are characterized by an alcoholic taste, but that's another topic. At 16 °P, our almost finished bock beer has just 2.9 % alcohol by volume, and so far no one has complained that the beer is lacking anything.

Since the last report, we have brewed a gose beer, but it can't really be called a beer. There are numerous recipes for gose beer, and such beer from the local area is characterized by a subtle taste of coriander. We are very pleased with the result and have been able to achieve an alcohol content of just 2 % vol.

We have also brewed a top-fermented pale ale using four different hop varieties. With these trials, we are also testing how close we can get to a Pilsner with top-fermenting yeasts and bottom-fermenting yeasts that tolerate temperatures of up to 20 °C. Like the large breweries, we have noticed that there is less demand for pilsner beers due to their pronounced bitterness, and the demand for pilsner is rather manageable for us. We no longer brew wheat beer because it is only rarely in demand, in contrast to our pale ale beers. Nevertheless, we are brewing a nice pilsner with at least four different classic aroma hop varieties for the 250th anniversary celebrations of Clausthal University of Technology, and we will be using a fine Czech Pilsner yeast for fermentation.

Top-fermented beers need just 2-3 days for complete fermentation, especially in combination with the isothermal high-temperature mashing process, and if you use a well-sedimenting yeast, these beers are mature after 4 weeks without any off-flavors and are almost clear without filtration. The current Helle has an alcohol content of just 2.5% vol. at 11.5 °P.

The previously announced bachelor's thesis is currently investigating how the temperature during isothermal high-temperature mashing of a single-variety Pilsner malt affects the subsequent alcohol content. Preliminary tests last year showed that this variety leads to different alcohol contents in the beer depending on the mashing temperature. As these results are to be published in a specialist journal, we will withhold detailed information at this point. We will only reveal that we set an original gravity of 11.5 °P for all these beers and ferment the wort under pressure in cylindrically-conical fermentation vessels with a Czech Pilsner yeast.