May 2024

We brewed a new Pilsner beer on May 21, 2024, a total of 200 liters in two brewing processes, which will be fermented and matured in our "Tank Siegfried" from the LalBrew Diamond. The base batch consisted of Pale Ale malt, supplemented with Carapils, and after conditioning the malt was milled with our MattMill Professional.
As we had very good experiences with conditioned malt and the BrewTools 150 Pro for at least one brew, we brewed using the malt pipe technique this time. Around 115 liters of water were heated to 82 °C in the BrewTools, and after mashing in, which took a good 5 minutes with a honey whisk, we reached the target temperature of 76 °C, which was kept constant for 30 minutes.
The mash was then already iodine-normal, and this was followed by around one hour of lautering, with a secondary pour. Despite the perfectly preserved husks, lautering took longer than in previous brewing projects, and we are currently wondering whether the water composition in Clausthal, which is probably not uniformly stable in terms of calcium salts, could also play a role here.
After the end of lautering and the addition of sour beer to adjust the pH value, we obtained around 115 liters with an original gravity of around 11.5 °P, which was then boiled with non-isomerized bitter hop extract for 60 minutes. After 30 minutes, an aroma hop was added, with a further addition of aroma hops after boiling in the whirlpool. With both boils and the same total amount of water, we achieved the same original gravity with a deviation of only 0.1 °P, which already speaks for good reproducibility.
Since we obtained bittering values in the beers brewed since March 2024 that were only about 2/3 of the calculated and earlier values, we increased the hop quantities by 50% this time. We should achieve a bitterness of 30 - 35 IBU units. As the water on May 21 left many lime stains on the taps, we are optimistic that the bitterness will not deviate too much upwards. The test strips for calcium ions will be delivered in the next few days, so we will have at least semi-quantitative information on the lime content in the "brewing water of the day" on each brewing day.
All our tanks are currently full and there are mature beers in the cooling chamber, most of them filtered, which are now being gradually released. We have had mixed experiences with candle filters, but we will report on this at a later date. In principle, it is possible to filter the beers largely clear without any loss of taste, but the throughput rate is heavily dependent on the pre-clarification of the beers and, with the same turbidity, also on the respective yeast.
So far, it has not proven to be expedient to filter a cloudy beer in this way. After 20 liters at the latest, the individual filter has become clogged and then either progress is very slow or the filter has to be frequently rinsed with brewing-grade sterile water. Apart from the fact that losses occur, the time required is considerable. For cost reasons, but also due to the limited space available, filtration as used in large breweries with precoat filters and cascaded plate filters is not feasible. However, we are still looking into another option. Therefore, as before, the beers will continue to mature in the cooling chamber for a good 2 months after 2 - 3 weeks in the tank and, depending on the beer, will only be filtered after this time. The beers from the brewing processes described on this website are therefore only released after approx. 3 months. We do not filter our pale ales or our less frequently brewed wheat beers, which can sometimes be released after 6 weeks.

Who is not familiar with Pilsner beer, which is one of the most frequently brewed beers in German breweries. It is characterized by a yellow to golden yellow color, it can have a distinct hop bloom, and it is rather bitter with 30 - 40 IBU units. With an original gravity of 11.5 °P, the alcohol content is around 5% vol. and a Pilsner beer from large breweries is clearly filtered. As a bottom-fermented beer, a Pilsner beer is rather easy to brew if the technical requirements are met. The malt bill is based on Pilsner malt, rounded off with specialty malts such as Carahell or Carapils. For the bitterness, a bittering hop is used as pellets or extract, and for the aroma, classic hops from the Hallertau are used, such as "Tradition", "Mittelfrüh" or even those from Tettnang, to name but a few. Most commercial Pilsner beers are fermented with the bottom-fermenting yeasts W34/70 or W34/78. As these yeasts produce a certain amount of buttery-tasting diacetyl, a longer storage period or fermentation under excess pressure is required.
We used a batch consisting of Pale Ale malt and Carapils for 50 liters of Pils and mashed it isothermally at 78 °C. In our opinion, Pale Ale malt produces a better full-bodied beer than Pilsner malt, and Carapils improves the foam stability. In our 50/70 L system with agitator, the mash was iodine-normal after 30 minutes, and in our experience, a longer mashing time has hardly any influence on the achievable original gravity, as saccharification continues during lautering anyway. In our experience to date, it does not make a significant difference whether mashing takes place for 30 or 60 minutes before a 30 - 60 minute lautering process follows, the achievable original gravity is almost identical and we have not been able to determine any difference to a 2- or 3-stage infusion process with the same total time. The brew was boiled in the BrewTools 150 Pro for one hour with a bittering hop extract from Yakimachief, Hallertauer Mittelfrüh was added in 2 doses for the aroma, with the aim of achieving a bitterness of 35 IBU units. The brew is fermented in "Tank Ulla" with Lallemand "Diamond", a bottom-fermenting yeast whose characteristics are close to those of W34/70. With an original gravity of around 11.5 °P, we expect an alcohol content of 2.3 % vol. based on recent results, an emerging lower limit with maltotrio-positive yeasts.
 

On the same day, we also brewed a Helles with the same equipment, using the identical procedure. The pouring differed slightly from that of the Pilsner beer and also contained a little melanoid malt. This is intended to give the beer a little more "body" in terms of taste and a slightly deeper color compared to the Pilsner. Mashing took place at 78 °C, and the wort was boiled with the aforementioned bittering hop extract from Yakimachief; for the aroma, we used Hallertauer Mittelfrüh and a hop extract from Yakimachief suitable for the whirlpool in the "Citra" variant. This aroma hop is intended to give the beer a very subtle fruity-aromatic profile. The calculated bitterness should be between 25 and 30 IBU units, i.e. somewhat milder than the Pilsner, and we also expect the alcohol content to be approx. 2.3 % alcohol by volume. The brew is fermented in "Tank Alex" and, like the Pilsner beer, the beer should be matured at the end of June / beginning of July. Both beers are then filtered through a candle filter to produce clear beers.
After a test phase in which we learned a lot about filtering with candle filters, we will filter most beers in future, but not our pale ales and wheat beers. A certain amount of turbidity is more desirable in a pale ale, and we can control it well with well-settling yeasts, and a certain amount of turbidity is expected in a wheat beer anyway. Filtration is a great advantage for the stability of our alcohol-free and pasteurized beers in particular, as well as for our gluten-free beers, which we do not brew regularly.

Our Schwarzbier is one of the most popular beers in our brewery, especially in summer. A Schwarzbier is usually based on dark Munich malt, the coffee-like aromas typical of such a beer are achieved with Caramünch and intensified with roasted malts such as Carafa or Chocolate Malt. We also use some melanoid malt and a small amount of smoked malt in the pour to give the beer a hint of smoky aroma. To deepen the color, we used roasted malt beer from Weyermann.
This time, to keep the effort on Father's Day, May 9, 2024, to a minimum, we (or one of us) brewed using the malt pipe technique and added 130 liters of water at a temperature of 82 °C in our BrewTools 150 Pro. A total of 23 kg of the malt mixture was mashed in, and after mashing, the temperature dropped to 76 °C, which was kept constant for 60 minutes.
In the meantime, we condition our malt, for which we had to slightly adapt our grist mill, the new MattMill Pro from MattMill, which was ultimately developed as part of a research project. With this small modification, which was implemented in consultation with Matthias Hoßfeld, conditioned malt can now also be milled without any problems. As a side effect, we have almost no more dust formation, which is not only beneficial for cleanliness in the malt store, but also minimizes exposure to malt dust, which can lead to malt fever, especially in allergy sufferers. Even the dreaded lump formation during mashing is no longer a significant problem when using conditioned malt.
If you read the brewing textbooks, nobody would dare to mash an allegedly low-enzyme malt such as Munich malt, mixed with 30 % enzymatically inactive specialty malts, at 82 °C and then mash it at 76 or even 78 °C for 60 minutes. The fact is, however, that the mash was already iodine-normal after 30 minutes and the in situ extract yield only increased by less than 1 °P during the following 30 minutes.
How can this be? A scientific discussion on this would probably fill an entire evening and would probably be controversial, but you have to bear in mind that up to 30 new barley varieties are registered in the European Union every year. In Germany, malting barley is continuously being developed through breeding in the so-called Berlin program, and brewing malt rarely consists of a single barley variety. Currently, malting barley (often) consists of around 50% of the enzyme-rich variety "Avalon", other varieties in the mix can be "Quench", "Accordine", "Leandra", "Irina" and several others.
However, Avalon is now gradually being replaced by better barley varieties, and so brewing malt is constantly improving. Malting plants are highly specialized operations, and the maltsters, master maltsters, brewers and master brewers in these plants are constantly developing the processes, so that today there are malts on the market that are very well suited for isothermal high-temperature mashing, even if this objective was perhaps never the main focus. The scientific question must also be allowed as to whether the molecular structure of alpha-amylase has not also changed in the course of these many years of continuous development.
We only used 10 liters of wort after lautering and then had to dilute the wort to almost 130 liters in order to achieve the target original wort of 11.5 °P, with which the alcohol content of the finished beer should be around 2.5 % vol. The wort was boiled in the BrewTools for one hour with a non-isomerized bitter hop extract from Yakimachief, another small amount of this hop extract was added 5 minutes before the end of the boil, and the calculated bitterness in the finished beer should be 30 IBU units.
During brews in March, which were not reported on in detail here, we unfortunately had to observe that hops from a small pack were incorrectly labeled or that the pack did not contain the hops we thought we had bought. A Pilsner, which was designed for 30 IBU units, appeared conspicuously mild in taste in terms of bitterness, and the measurements showed that the measured bitterness of all four beers was only approx. 2/3 of the calculated bitterness. Instead of 30 IBU units for a pilsner, we only achieved 20 IBU units, and instead of 20 IBU units for a darker beer, we only achieved 13 IBU units - unsuitable for the beers we were aiming for. We never had this problem with bitter hop extracts from large companies, the measured bitterness rarely deviated by 2 IBU units from the target value, so we now consistently use bitter hop extracts again to adjust the bitterness.
After 15 minutes in the whirlpool, the boiled wort was divided up between the 50/70 L "Tank Martin" and "Tank Mathias" CCGs via a trub filter and a plate heat exchanger, and a good 50 liters of wort are now fermented in each tank with the Lallemand "Diamond" in the second guide. Like many larger breweries, we have found that bottom-fermenting yeasts in particular ferment better and sediment better from the second pitch, which has the advantage that the beers clear faster and can then be filtered with less effort.
However, the multiple pitching of bottom-fermenting yeasts, which are ultimately hybrids of Saccharomyces Eubayanus and Saccharomyces Cerevisiae, has its limits, and different fermentation properties must be expected from the 5th pitch. We use bottom-fermenting yeasts a maximum of 3 times again. With the malt pipe technique, we have always achieved slightly higher alcohol contents than in mash tuns with stirrers, but we still expect less than 3% alcohol by volume. We are also curious to see how the noticeably reduced lump formation of the conditioned malt in the malt pipe during mashing will affect the alcohol content later on.

 

Update: Our suspicion that the problems with bitterness described above could be related to an incorrectly labeled hop delivery has unfortunately not been confirmed, as the same problem also occurs with bittering hop extract. It is unlikely that a small pack and a hermetically sealed can from a well-known manufacturer would be mislabeled at the same time. We first observed these problems with beers brewed in March 2024. Around February 2024, Stadtwerke Clausthal commissioned a new waterworks for Clausthal, and the water is now being treated with lime, as in Zellerfeld in another waterworks, which changes the pH value as well as the composition of the water. Please refer to the website of the Clausthal municipal utility company using the search term "water quality".
Apparently there are fluctuations in this process, because sometimes you see a few limescale stains on the taps, sometimes many when the water dries up. The water quality has a massive influence on the wort break, and in addition to the pH value, which is rather easily adjusted by sour water, the calcium ions introduced by the scaling process are also responsible for this. In the textbook "Die Bierbrauerei", Volume 2 by Ludwig Narziß and Werner Back, the following can be read with reference to a literature citation: "Protein coagulation is promoted (by calcium ions). During mashing, they protect the alpha-amylase from heat denaturation, they also promote the activity of endopeptidases". Improved yeast sedimentation is also mentioned.
We can confirm a change in the wort break, whereby the wort break now flocculates better than before. Unfortunately, this wort curd also partially adsorbs the iso-alpha-acids formed during boiling, just as the sedimenting yeast also precipitates them. Converted into a concentration, 30 IBU means that there are 30 mg of iso-alpha acids in one liter of beer, and this substance determines the bitterness. The dissolved quantity is in turn in equilibrium with the quantity adsorbed on the wort break, and if the wort break, which consists of many components, favors the adsorption of the bitter substances, less is available for the bitterness in equilibrium.
In a brewery, it is possible to adjust to a change in water quality. If the composition of the water remains reliably stable, we have to adjust our hop additions upwards by around 50% in order to return to our previous values for bitterness and aroma. However, we run into difficulties if we have very soft water available on a brewing day. Then our beers might become atypically bitter and we would only be able to blend such a beer with another one that is less bitter.
The problem would be solvable for the beers we release, but it becomes critical if we brew research beers for later publications and have to deal with different brewing water in the necessary three test series. Then we would be comparing the proverbial apples with pears, and the non-reproducible results would not be publishable. As a first measure, we have ordered a test kit with which we can obtain semi-quantitative statements on the content of calcium ions in the "brewing water of the day" on brewing day. We will now have samples tested at regular intervals and, if there continue to be major fluctuations in the future, we will have no choice but to install an automatic water treatment system. Many large breweries treat their water in this way and the technology is available. However, the question remains as to what costs we will incur as a university institute in this case.

On May 7, we carried out a trial on a Pale Ale/ NEIPA with less than 2% alcohol by volume based on preliminary tests from a bachelor thesis. Up to now, such beers with an original gravity of around 11 °P have had alcohol contents of 2.3 - 2.4 % vol. These are achieved by brewing consistently according to our isothermal high-temperature mashing process and avoiding the hop creep effect of hops by either enzymatically inactivating the aroma hops for dry hopping beforehand or by working with hop extracts that have no enzymatic activity whatsoever.
With the brewing malts currently available, the alcohol content mentioned seems to be the lower achievable limit at an original gravity of around 11 °P if yeasts that ferment maltose and maltotriose are used. The alcohol content can only be reduced by lowering the original gravity or by using yeasts that do not ferment maltose or maltotriose. In our current experiment, we fermented the brew with the maltotriose-negative top-fermenting yeast "Windsor" from Lallemand Brewing in our "Tank Volker". We therefore mashed a mixture of Pale Ale malt, Carapils and Melanoidin malt in our BrewTower 140+ isothermally at 78 °C and designed it as a front wort beer.
The few improvements to our "brew tower", i.e. two additional stirring paddles and a more powerful circulation pump, have made mashing much easier, as hardly any lumps form during mashing and these break down very quickly. In the next few days, the mash tun will be fitted with two baffle plates, which will further improve the mashing process.
We mashed once for 30 minutes and then boiled the wort in our BrewTools system; in the second process, we mashed for 60 minutes because the BrewTools was busy boiling the first wort. It is interesting to note that there was only a slight difference in the original wort after mashing; mashing for 60 minutes has hardly any advantage over mashing for 30 minutes, the residual saccharification takes place in the lauter tun or in the brewing kettle anyway. It should be noted that both mashes were already visually iodine-normal after 30 minutes at 78 °C.
Both brews were boiled with a bitter hop extract from Yakimachief, with a target value of a mild 20 IBU units. The whirlpool hopping was carried out with a hop extract from Yakimachief in the "Citra" variant, and for the dry hopping we used the "Spectrum" product from BarthHaas in the "Galaxy" variant. The combination of these hop extracts results in aromas of tropical fruits.
Both brews are fermented, as outlined above, with the maltotriose-negative yeast "Windsor" from Lallemand Brewing. We would like to say a few words about this yeast with regard to our cylindrically conical fermentation vessels (CCVs). In the summer of 2023, after cleaning our CCVs using the CIP process with alkaline and acidic solutions at approx. 40 °C, we observed that all beers fermented with maltose- or maltotriose-negative yeasts in the previously cleaned CCVs "fermented through" despite multiple rinsing steps. Maltose and maltotriose were no longer detectable in the chromatograms measured by HPLC. The only explanation was that "somewhere" in the CCG, yeast cells from a previous fermentation had survived and then fermented maltose and maltotriose.
After consulting the manufacturer of the CCGs, we therefore adapted the cleaning of the CCGs. Cleaning with lye and acid is carried out at 50 °C. In the final step, the CCG is filled to 3/4 full and rinsed with hot water at around 80 °C for one hour. The spray head of the CCC distributes the hot water virtually everywhere in the CCC, so that no yeast cells from a previous fermentation should be able to survive. We will monitor the fermentation process and, after a certain time, use HPLC to determine whether maltotriose is still present and whether its concentration has changed in comparison with the unfermented wort. If this is not fermented, the result should be a full-bodied, fruity and aromatic Pale Ale / NEIPA with 1.8% alcohol by volume.
Our experience to date also strongly suggests that we can use a candle filter with a pore size of 450 nm to obtain a beer that no longer contains any living yeast cells and is therefore stable for storage in barrels. However, such filtration requires that the yeast has settled well beforehand. This means that pasteurization of this beer may not be necessary, at least for kegs. We are very much looking forward to the result.
 

We are currently brewing some non-alcoholic beers with a maximum of 0.5% alcohol by volume using so-called maltose-negative yeasts, which have been reported on this website on several occasions. The challenge with these yeasts is to work extremely cleanly in the cold range and to control the fermentation process in order to then gently pasteurize the pressureless fermented beers in good time before they are carbonated. There are only a few such maltose-negative yeasts on the market, one of which is LoNa from Lallemand Brewing, which is described by Lallemand as follows:
"LalBrew® LoNa™ is the first maltose-negative Saccharomyces cerevisiae strain specifically developed using hybridization for brewing clean low-alcohol and non-alcohol beers (reduced worty flavors, POF-negative and H2S-negative). Advanced classical and non-GMO breeding methods were used to select a strain that does not consume maltose or maltotriose, resulting in very low attenuation. As a S. cerevisiae strain, LalBrew® LoNa™ performs like an ale yeast producing a clean and neutral aroma profile with no phenolic flavors, and significantly reducing aldehydes that cause worty flavors. Additionally, the patented technology from the University of California Davis (USA) ensures that the strain will not produce sulfurous off-flavors, allowing the malt and hop flavors to shine through." (Text in quotation marks taken from the Lallemand Brewing website on 05.05.2024).
This yeast cannot be used to produce wheat beers with their typical clove or banana aroma, nor Pilsner beers, as the yeast does not produce hydrogen sulphide. In our experience, it also does not ferment quite as neutrally as the manufacturer claims; at fermentation temperatures of around 20 °C, it produces very subtle ester aromas, which are by no means unpleasant. In our opinion, it is therefore quite suitable for the production of non-alcoholic Pale Ale beers, especially if enzyme-free hop extracts are used for dry hopping.
And so we brewed a non-alcoholic Pale Ale on May 5th. Apart from a few exceptions, we brew exclusively using our isothermal high-temperature mashing process, whereby we vary the mashing temperature between 72 and 78 °C. This time, we mashed a malt mixture consisting of 50% Pale Ale malt and 50% Munich malt for 60 minutes at 78 °C in our 50/70 L system with agitator. With a post-pour of 10 liters in the brew kettle (our BrewTools 150 Pro), we obtained an original gravity of 14 °P, and after dilution to 100 liters and the addition of sour beer, a corresponding 7 °P, which represents the limit for brewing beers with a maximum of 0.5 % vol. with maltose-negative yeasts that also metabolize sucrose.
We boiled the wort for one hour with a non-isomerized bitter hop extract from Yakimachief and adjusted the bitterness to around 30 IBU. The whirlpool hopping was carried out with special hop extracts from Yakimachief in the "Citra" and "Mosaic" variants. This has already laid the foundation for tropical fruit aromas in the hot range. To further emphasize these aromas, we carried out a cold hopping with BarthHaas Spectrum in the "Galaxy" variant, i.e. this hop extract was added to the wort at the same time as the yeast. This hop brings aromas of peaches/apricots and pineapple to the beer, resulting in a very fruity and aromatic non-alcoholic pale ale. We will be monitoring the fermentation process over the next few days and based on previous results, primary fermentation should be complete after around 3 days with an alcohol content of 0.5% vol. As with the beer brewed on 30.04., pasteurization will then take place at 63 °C without pressure, followed by carbonation. Depending on the turbidity, the beer may be filtered later.
 

At this point, we would like to say a few words about hop extracts. Anyone who reads this website in detail will see that we work with both hop pellets and hop extracts, but in fact no longer with hop cones, as these are very difficult to handle in our systems in terms of process technology. Opinions differ as to which form of hops is better. In the future, however, we will increasingly use non-isomerized hop extracts again, especially for adjusting the bitterness.
Our experience with bitter hop extract has shown that the information on the alpha acid values on the hermetically sealed cans is reliable and that the beers contain the bitterness that was previously calculated quite precisely. Unfortunately, we have never been able to achieve such consistency with hop pellets from small packs, for which there are several possible reasons, which we will not speculate on here. Bitter hop extract ensures the scientifically necessary reproducibility for our research work in particular.
A lot has happened in the field of aroma hops in recent years, and there are now excellent hop extracts, for example from BarthHaas and Yakimachief (as well as others), which can be used in hot and cold brewing. Even if these hop extracts concentrate on hops with fruit aromas for the production of pale ale beers, the first liquid products made from the more classic hops such as Saazer, Perle or Hallertauer Mittelfrüh are now also available, which can be used in beers such as "Pils" or "Helles". For our research work, which focuses on the isothermal high-temperature mashing process, this provides the opportunity to achieve the best possible reproducibility together with filtration via candle filters. Ultimately, every brewing test must be carried out three times to achieve a certain statistical relevance, and if there are excessive deviations between the tests, e.g. in terms of bitterness, questions are raised when reviewing a manuscript that may require further tests.