July 2024

On July 29 and 30, 2024, we brewed with single-variety Pilsner malt, i.e. malt that was produced from just a single type of barley and provided to us by a medium-sized malt house. The variety used is considered to be strong in alpha-amylase, the protein content is low with a high degree of protein solubility. This barley variety is found to a certain extent in the mixtures of current malting barley.
We were interested in investigating how this malting barley behaves during isothermal high-temperature mashing. For this purpose, we mashed 10 kg of conditioned and crushed malt in a total of four trials at 72, 74, 76 and 78 °C for 40 minutes in 50 liters of brewing water with 1 °dH in our 50-liter system, which has a very powerful agitator and reduces the mashing process to around 30 seconds. The brewing water was previously mixed from reverse osmosis water and tap water. Lautering was carried out in the BrewTools 150 Pro, and in all four trials, 12 liters of secondary at 78 °C were applied.
In all these trials, the mash was iodine-normal after just 20 minutes, and after 40 minutes, in situ extracts of around 12 °P were achieved, very similar to all other previous trials under comparable conditions. We were surprised that saccharification was fastest at 78 °C and that the best overall extract yield was achieved at this temperature. These results raise the question of where the upper temperature limit for isothermal high-temperature mashing actually lies for this variety and what effect an even higher temperature has on sugar distribution.
The wort was boiled in the BrewTools 150 Pro with a non-isomerized hop extract from Yakimachief; aroma hopping was carried out in the whirlpool with Czech Saazer, a very fine aroma hop. After boiling, we replaced the water evaporated during the boil with reverse osmosis water and adjusted the wort to around 12 °P, whereby the volumes were almost the same in all trials. A certain weak point is the lautering, as this can differ slightly from trial to trial.
Each wort is fermented in a cylindrically-conical fermentation vessel at 12 °C without pressure using the Lallemand Brewing Diamond. Hopping and yeast are intended to produce Pilsner beers, and in addition to the subsequent alcohol content, we and the malt house that provided us with the malt are interested in other physico-chemical parameters of these beers. As Pilsner beers always require a certain maturation period, it will be October before we can fully evaluate these four beers. As an aside, it should be mentioned that the hardness of the tap water was relatively stable during the last brewing trials and was between 5 and 6 °dH. We currently mix our brewing water from 80% reverse osmosis water and 20% tap water, although we still determine the hardness of the tap water on a daily basis.

We brewed approx. 180 liters of a Pilsner beer on 18.07.2024 before the vacation season began. Since the beginning of the year, we have had major problems brewing authentic pale ales, and ultimately the limescale in the tap water to 5 - 6 °dH, which was also unstable at times, caused us real problems. Brewing Pilsner beers with such water is practically impossible, and so our Pilsner beers brewed with the previously less defined water, which will soon be released, are good, but not as good as they were last year. These Pilsner beers reminded a brewer friend of the Dortmund type.
On July 18, we were able to brew a Pilsner with defined water again for the first time. The day before, we mixed 260 liters of brewing water with 1 °dH from tap water, which we determined to be 5 °dH, and reverse osmosis water. As our reverse osmosis system can unfortunately only provide just under 2 l/min, we will install a second one in parallel, as mixing simply takes far too much time, during which it is almost impossible to carry out any other work - if you don't want to risk overflowing. A mixture of Pale Ale malt and Carapils was mashed in our BrewTower 140+ in two brewing processes, each in 130 liters of water at 78 °C. Thanks to improvements in the circulation, the installation of baffle plates and the conditioning of the malt, the previously feared lump formation no longer plays a significant role. The lautering process was carried out without secondary pouring, meaning that a front wort beer was produced.
The wort, to which sour cream was added beforehand to lower the pH value, was then boiled in our BrewTools 150 Pro with a non-isomerized bitter hop extract from Yakimachief, while Czech Saazer was used in two batches as pellets type 90 for the aroma. Its aroma is described as "earthy", "herbal" and "flowery" and contributes to the aroma of the well-known "Pilsner Urquell". The bitterness of our beer should be around 35 IBU, making it a very strongly hopped Pilsner. It is perhaps worth mentioning that the duration of mashing does not play too great a role in the achievable original gravity. We mashed once for 30 minutes and once for around 90 minutes, and in both cases we obtained almost identical original gravities of 11.6 °P at comparable volumes after boiling. Future trials will have to show to what extent the mashing time can be reduced even further.
We have implemented a technical change for the transfer of the wort to "Tank Siegfried" that significantly simplifies the filling of the tank and virtually eliminates the already low risk of contamination with foreign yeasts. Both wort types are fermented together at 12 °C with the bottom-fermenting yeast Diamond from Lallemand Brewing in the second fermentation run. In our experience to date, fermentation is much faster in the second fermentation with this yeast, and the beers also clarify much better, which in turn makes filtering easier. This yeast is maltotrio-positive, and with an original gravity of 11.6 °P, we expect an alcohol content of no more than 2.5 % vol. A pilsner needs a certain amount of time to mature, so it will not be released until around the beginning of October.

On May 7, 2024, we brewed around 180 liters (net) of a Pale Ale that was fermented with a maltotriose-negative yeast. For the typical pale ale aroma, the special whirlpool hop extract Dynaboost (formerly YCH 702) from Yakimachief in the "Citra" variant was used in the hot section, while the product Spectrum from Barth-Haas in the "Galaxy" variant was used for the cold hopping. We aimed for an alcohol content of less than 2 % vol. and achieved a pleasingly low 1.7 % vol. with an original gravity of 11.3 °P. All test drinkers so far have been very satisfied with this pale ale, and no one has complained about too little taste or too little alcohol.
This beer was also a test of whether our hot pasteurization of the cylindrically-conical fermentation vessels after their alkaline and acidic CIP cleaning is sufficient to reliably kill off any former yeast cells of maltotriosis-positive yeasts that may still be present. In future trials, we would like to use one of our 200 L CCGs with maltose-negative yeasts to produce non-alcoholic beers, as these are increasingly in demand, especially our non-alcoholic pale ales.
This first test was successful, so we brewed a new pale ale in a second test on July 11 with minimal modification of the recipe and filled the wort into the same recently emptied tank, whereby the remaining yeast was used a second time directly in situ. Ultimately, a sealed cylindrically-conical fermentation vessel is a bioreactor. The batch consisted of Pale Ale malt, Carapils and Melanoidin malt, mashed isothermally at 76 °C successively once for 30 minutes in the BrewTools 150 Pro (malt pipe technology) and once for around 50 minutes in the mash tun (with agitator) of our BrewTower. Boiling took place in the BrewTools for 60 minutes in each case, the bitterness was adjusted to around 30 IBU units using a non-isomerized bittering hop extract from Yakimachief.
The first aroma hops were added in the whirlpool with the product Dynaboost from Yakimachief, this time in the "Mosaic" variant. For the dry hopping in the cylindrically conical fermentation vessel, we again used Spectrum in the "Galaxy" variant. Both hop variants lead to aromas of pineapple, mango, peach, passion fruit and gooseberries and harmonize well with each other.
The tank was only opened each time to fill in the wort from above, otherwise the tank had been hermetically sealed since 7 May. With a small modification, the wort to be fermented will in future be filled into the respective ZKG without opening the tank. If no yeast cells from the brewing air have penetrated the tank, this should result in an alcohol content of just 1.6% vol. at an original gravity of 10.8 °P, which means that this beer could almost be declared "low in alcohol". But are cold-hopped pale ales actually beers in the legal sense? This question and its problems are explored in the category "News from everyday brewery life".

On July 2, 2024, thanks to our new reverse osmosis system, we were able to use soft water with 1 °dH for brewing for the first time since November/December 2023. The analysis of some earlier photos of calcification on the heating coils of our brewing equipment suggests that the municipal utilities began feeding calcified water into the pipe network between the beginning and end of November 2023. This is pretty much in line with our experience, and the last good pilsner we managed to brew was in November/December 2023, and we were probably just lucky that we had soft tap water available on that brewing day. After that, the pale beers, especially the Pilsner beers, were no longer of the same quality, and in February/March 2024 we realized "Houston, we have a problem!", even if we couldn't localize or even narrow it down yet.
 

We measured the total hardness of the tap water at 5 °dH on July 1, so our brewing water (main pour + post-pour) was mixed on July 1 from 80% reverse osmosis water and 20% tap water, a total of 200 liters for all steps combined. A control measurement confirmed the total hardness of 1 °dH of the brewing water mixed in this way - as expected. We now regularly check the hardness of our tap water, and on July 2 we received 3 °dH in the morning and 6 °dH in the evening. These measurements are carried out by several people at the institute and in the brewery in order to rule out systematic errors. However, without detailed knowledge of the process steps in the waterworks of the municipal utilities, we cannot be sure where these fluctuations in the total hardness come from.
However, before we started measuring the total hardness, we saw that there are fluctuations in the total hardness from the varying degrees of limescale deposits on the taps. As already described in the "News from everyday brewery life" section, such fluctuations are completely unproblematic for water as a foodstuff, but for scientifically correct work or even "just" for brewing Pilsner beers, such fluctuations are a major problem because not only the so-called residual alkalinity plays a role, but calcium ions also influence the brewing process in several places.

Due to the high demand, we brewed a total of 2x 60 liters of non-alcoholic beer on July 2nd. We conditioned a batch consisting of 11 kg of pale ale malt and 4 kg of melanoid malt, milled it with the MattMill Professional and mashed it in the BrewTools 150 Pro at 82 °C in 130 liters of water. The temperature dropped to 76 °C within a few minutes, and after 30 minutes we started lautering, which took around 30 minutes. The malt was washed out with brewing water at 78 °C until a volume of 150 liters was reached in the system. We added around 2 liters of sour beer and then boiled the wort with a non-isomerized bitter hop extract from Yakimachief for 60 minutes.
The evaporated water was then replaced with reverse osmosis water and an aroma hop extract (Hallertauer Perle) from Eisemann was added to the wort in the whirlpool. After 15 minutes, the wort, whose original gravity was around 7 °P with a pH value of 4.1, was transferred via a wort filter and a plate heat exchanger into two previously pasteurized stainless steel vessels, around 65 liters per fermentation vessel.
In one vessel, the wort is fermented with Saccharomycodes Ludwigii in the second fermenter, in the other with Cyberlindnera Misumaiensis in the first fermenter. The so-called Ludwig yeast ferments glucose, fructose and sucrose, the Cyberlindnera Misumaiensis only glucose. Based on previous brewing trials, the alcohol content should be a maximum of 0.5% vol. in the first case and a maximum of 0.3% vol. in the second case.
At first glance, the pH value of the wort may seem surprising, as trainee brewers and maltsters learn the rule of thumb at vocational school that the wort should have a pH value of 5.4 and the finished beer 4.5. However, with maltose-negative yeasts, it should be noted that there is only a very slight drop in pH during fermentation. As a sufficiently low pH value is also important in order to precipitate extremely bitter hop resins (the black sticky rim on fermentation vessels), such wort must be acidified. The only option compatible with the so-called Purity Law is to add souring agent, ultimately a lacto-fermented malt extract. According to our experience to date, the reduction in the pH value due to fermentation will be no more than 0.1 - 0.2 pH units, so that the finished beers should later have a pH value between 3.9 and 4.0, a not untypical value for top-fermented beers.
Even at only 7 °P, the Ludwig yeast produces a full-bodied beer in which honey aromas can be perceived; the Cyberlindnera Misumaiensis certainly gives the beers a certain Pils character. We will monitor the fermentation process over the next few days and gently pasteurize the beers when they reach 0.5 or 0.3% alcohol by volume and carbonate them after cooling. Pasteurization is absolutely essential, as we cannot rule out the possibility that common yeast cells from the brewing air have found their way into the wort. Although it does take some time for them to ferment maltose and maltotriose to any significant extent, it would be too risky to forego pasteurization. After a further 4 weeks or so, the beers are filtered before they are finally dispensed. As soon as these two beers have been pasteurized, we will brew our very well-received alcohol-free pale ale with the Lallemand Brewing LoNa and an alcohol-free wheat beer with a Saccharomyces Jurei - actually a nice summer beer, if it were summer ....

All our tanks are currently empty, and in the next two weeks we will be brewing a new pilsner with < 2.5% alcohol by volume for Tank Siegfried using our redefined brewing water, and a pale ale with around 1.7% alcohol by volume for Tank Volker. For the four small tanks, we will use single-variety barley malt to investigate how the isothermal mashing temperature will affect the character of a pilsner and its head using pilsner beers. After that, we'll have to start thinking about the bock beers for autumn and winter and also plan the beers for the 250th anniversary celebrations of Clausthal University of Technology in 2025.
After the very varied experiences of the last 7 months or so with tap water, which is unstable for brewing purposes, we are very happy to have invested in a reverse osmosis system and are now able to mix our brewing water in a defined way. In our project to produce gluten-free beers based on quinoa, which ends in September, some brewing problems may also have been a result of the unstable water in terms of hardness. The next brewing trials will start shortly. The only disadvantage compared to the previous soft tap water is that our reverse osmosis system can only provide 1.8 l/min, so we have to mix the brewing water the day before until a better technical solution is found, especially as mixing 260 liters of brewing water from 20% tap water and 80% reverse osmosis water takes around 2 hours.