February 2024

As part of a four-week student internship, we brewed a "Claus-Zellersch" on February 19, 2024, using pure Pale Ale malt and our isothermal high-temperature mashing process. The entire brewing process took place in the Brewtools 150 Pro, and we achieved an original gravity of 12.3 °P as a front wort beer. We adjusted the bitterness to approx. 25 IBU with a non-isomerized hop extract from Yakimachief, and Rottenburger and a small amount of Lemondrop were added as aroma hops in the whirlpool at 85 °C. At this temperature, the hop enzymes are safely denatured, hardly any bitter substances are transferred into the wort and the aromatic substances of the hops are well transferred into the wort.
The wort is fermented at around 20 °C without pressure using Lallemand Brewing "Kölsch", a typical top-fermenting Kölsch yeast. There are many stories about Kölsch beer, and it is often said that although the beer is very light in taste, it still reaches alcohol levels of 5 % vol. and above at original wort temperatures of around 11.5 °P. In contrast, we do not expect our beer to have more than 3 % alcohol by volume.
Kölsch beers are not necessarily known for their stable head, which is also due to the yeast, which is why they are usually drunk rather quickly from tall 0.2 l glasses in Cologne, sometimes as a whole meter, and sometimes perhaps too quickly. The Kölsch convention limits the use of the name "Kölsch", and this beer is one of the protected regional specialties. With a twinkle in the eye, you could say that a Kölsch is only a Kölsch if you can somehow see Cologne Cathedral from the brewery in Cologne. Well, you can't see it from Clausthal-Zellerfeld with the best will in the world, but from the roof of our building we can see both the church tower of the church in Clausthal and the church in Zellerfeld. So it makes sense to call our beer "Claus-Zellersch".
To do justice to the research character of this student internship, we added a gluten-degrading enzyme to the wort for the main fermentation. At events at Clausthal University of Technology, which we supply with beer, we are regularly asked whether we can also produce gluten-free beers. We not only monitor the fermentation process, but also measure the gluten content as a function of time at regular intervals during primary and secondary fermentation and the subsequent maturation of the beer using an ELISA reader. This is a detection method using antibodies, ELISA stands for "Enzyme-linked Immunosorbent Assay". The realistic detection limit for gluten using this method is 10 mg/kg, and most people suffering from coeliac disease cope well with these low gluten levels. Currently, foods with a gluten content of < 20 mg/kg can be labeled as "gluten-free". Our aim in this practical course is to achieve a gluten content below the detection limit. The enzymatic degradation of gluten, which is broken down by the enzyme wherever the amino acid proline is found in gluten, is influenced by many parameters, e.g. the settling yeast can also precipitate the enzyme, or the unavoidable lees adsorb the enzyme, resulting in reduced gluten degradation.
After approx. 2 weeks, the beer is filtered and, depending on the gluten content achieved by then in the lager barrel, further enzyme is added if necessary. From previous trials, we can expect the beer to be mature and gluten-free in approx. 4 weeks. The addition of a gluten-degrading enzyme contradicts the so-called "Purity Law", i.e. the finished beer may not be called beer (only in Germany?), but the enzyme is permitted under food law, which takes precedence over the Purity Law. We might call this beer "research beer" or just "alcoholic beverage" with regard to the Purity Law and for people who suffer from coeliac disease or gluten intolerance. It is also conceivable that we could apply for a permit to offer such beers as "special beers". This also applies to our quinoa-based beers, which we currently brew with a small amount of barley malt for flavor reasons. Using a gluten-degrading enzyme, these beers quickly achieve gluten levels below the detection limit.

As part of a four-week student research internship, we are currently investigating how the original gravity of a beer brewed using the isothermal high-temperature mashing process affects the taste. For these experiments, a total of four beers were produced in which the original gravity was successively reduced, starting at 12 °P, which also reduced the alcohol content. The amount of hops was identical in all trials, and all beers were fermented with the same bottom-fermenting yeast.
In order to be able to assess the taste later without distorting it, the matured beers were filtered through a candle filter. We have chosen the pore size of this filter so that yeast cells and any lactic acid bacteria present are retained, but not the aromatic substances. We tested the filter with the pilsner brewed on 17.11.2023, which was fermented with the Whitelabs WLP-830. Unfortunately, the cells of this bottom-fermenting yeast strain settle less well than those of the Diamond from Lallemand Brewing, which is why the beer was still not fully clarified by sedimentation at the beginning of February. The filtered beer, on the other hand, is completely clear and we have not noticed any loss of aroma; on the contrary, the mouthfeel, which is difficult to describe and certainly individual, seems more harmonious to us because of the removed yeast cells.
At 11 °P, this beer has an alcohol content of just 2.4 % vol - our lowest value to date for a pilsner beer. We will be taking a closer look at filtering beer in the coming months, especially as the commercially available filter cartridges differ in terms of pore size. We need to find the optimum balance between clarification and throughput for our brewery.

On February 9, we brewed a new NEIPA, the recipe for which was based on the beer from November 4/5, 2023. However, the grain bill consisted of 100% Pale Ale malt, which was milled with our new MattMill Professional, fortunately with negligible dust formation, which also minimizes the risk of contracting malt fever. Furthermore, this is a front wort beer, i.e. we measured the main pour in such a way that we did not have to give up any secondary pours.
Mashing was carried out in parallel in the BrewTools 150 Pro and in our BrewTower 140+ at 76 °C for 30 minutes. A longer mashing time has only a minor effect on the in situ original gravity; any secondary saccharification takes place during lautering. The mashing process in both systems was technically unremarkable, but after boiling we only achieved the expected original gravity of 11.5 °P in the BrewTools system, and unfortunately only 9.5 °P in the BrewTower.
Two problems came together in the latter: firstly, the agitator with its two rather small paddles and the low speed of the geared motor does not achieve ideal mixing, which is necessary for isothermal high-temperature mashing. This can result in lumps that only gradually break down. To solve this problem for future brews, we asked the manufacturer for 2 additional paddles to improve mixing.
Secondly, the heating capacity of the brewing kettle, which unfortunately cannot be regulated via the control system, was oversized at 10 kW for a wort volume of around 115 liters. The wort repeatedly boiled over and thus partly found its way through the vapor condenser into the sewage system; in addition, water also flowed from the vapor condenser into the brewing kettle, so that the wort was diluted. The influx of fresh water was recognizable by the falling temperature in the brewing kettle. To prevent this boiling over in future, the connection will be modified so that the second of the two 5 kW heating cartridges can be switched off via a switch when the boiling temperature is reached. This should solve the problem of boiling over.
The bitterness was adjusted to approx. 15 IBU using a hop extract from Yakimachief, while the whirlpool hopping was carried out using a special hop extract from Yakimachief in the "Mosaic" variant. Both wort types were fermented with the Ebbegarden Kveik in the presence of the hop extract Spectrum from Barth-Haas in the "Galaxy" variant in our "Tank Volker". The beer was already finally fermented on February 13 and has an alcohol content of a pleasingly low 2.2% vol. at an original gravity of 10.4 °P. The yeast itself produces aromas of tropical fruit, which are complemented by the hop extracts used.
We will be filtering at least part of this beer in a few weeks' time in order to investigate how the naturally cloudy NEIPA differs in taste from its filtered counterpart. If this mild filtration proves successful, we could increase the throughput of our brewery by reducing the time the beers spend in the tanks, because sometimes, especially when many events have taken place at Clausthal University of Technology in quick succession, we have run out of stock. After several events last year, we only had 50 liters of beer left in the cold store, and after all, what could be worse than a brewery with no beer .....