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As previously mentioned, we only report superficially here on the brewing projects that are being worked on as part of student theses. We are also holding back a little on information about our publicly funded project, in which we are producing tasty beers based on quinoa. However, we can say that the quinoa beers are better when they are made with quinoa malt instead of unmalted quinoa.
We do try out new things in student theses, and as not everything works right away, one or two brews unfortunately have to go down the drain. On the other hand, we tried out a lot of new things in the bachelor theses carried out in the winter semester 2023/2024 and gained valuable inspiration for future work. For example, we definitely see potential to reduce the alcohol content of our beers even further.
We will also be reporting on a new challenge in more detail here soon. Stadtwerke Clausthal built new waterworks last year, and the surface water, which used to be very soft at 1 - 2 ° dH and ideally suited for Pilsner beers, is now lime treated as tap water with calcium carbonate to 7 - 7.5 ° dH. The resulting higher pH value now requires the addition of souring agent in order to achieve a microbiologically safe pH value of 4.5 or below in the finished beer. Calcium ions can have a fundamentally positive effect on the brewing process. For example, protein coagulation is promoted and alpha-amylase is protected; calcium ions also promote flocculation of the yeast. However, this will have to be clarified in the coming brews and it remains to be seen whether the character of the beers will change slightly due to the change in water. At least we won't get bored this way.
On 18.03.2024, however, we brewed a regular beer again, a top-fermented Helles based on an earlier recipe. We have already adjusted the amount of sour beer upwards a little. This time, we recombined our existing equipment and produced around 200 liters of beer in two brewing processes. During one of the last brewing processes, we had massive boiling problems with our BrewTower, which is why we now only use the lower container to preheat the main pour. Specifically, we heated 130 liters of water to 80 °C in the upper container, i.e. in the mash tun and lauter tun, and then mashed in 22 kg of malt grist. After resting for 30 minutes at 76 °C, the front wort was transferred to our BrewTools 150 Pro for 30 minutes, where it was boiled and hopped. During the heating phase in the BrewTools, we drained the BrewTower and then pumped the preheated mashing water from the lower tank to the top. After reaching 80 °C, we mashed in for the second time, and we mashed for a total of almost 90 minutes during the second brewing process until the BrewTools system was free again to receive the wort after whirlpooling, knocking out and cleaning.
It was interesting to note that a mashing time of 90 minutes had little effect on the extract that could be achieved compared to a mashing time of just 30 minutes. In both cases, the wort was boiled for 60 minutes with Hallertauer Magnum to adjust the bitterness, and Hallertauer Mittelfrüh was added after 30 minutes of boiling. Whirlpool hopping was carried out at around 85 °C with Hüll Melon (Wethop). We have previously combined these aroma hops in a bottom-fermented beer with the same bill of Pale Ale malt and Carahell, and the result was a delicately bitter and subtly fruity aromatic beer. This time we opted for top fermentation and used the neutral fermenting and very well sedimenting "Nottingham" from Lallemand Brewing. The yeast is said to have pseudo-lager properties, but the result is not a pilsner. With an original gravity of 11.3 °P, we expect approx. 2 % alcohol by volume. Top-fermented beers are generally matured more quickly than bottom-fermented beers, so the beer should be matured, clarified and therefore easy to drink by the end of April.
We needed a total of 7 hours for both brewing processes, which is a very good value. Thanks to the new configuration, cleaning the brewing equipment was done quickly. We could save another hour if we only mashed in the BrewTools system, but the malt pipe technology for isothermal high-temperature mashing has not proven to be ideal so far. Compared to systems with agitators, we get slightly higher alcohol contents, which is due to the fundamental disadvantages of malt pipe technology.
Instead of reporting on brewing trials here as usual, this time we have decided to outline some new findings on our brewing equipment, results on allegedly low-enzyme malts and surprises with a gluten-degrading enzyme.
In our research brewery, we focus on the isothermal high-temperature mashing process to reduce the alcohol content of beers. In the course of almost 200 trials, we have established that mash kettles with agitators are superior to systems with malt pipe technology. The background to this is that homogeneous mashing with an agitator (in our case) is completed within a minute, whereas the malt pipe technology requires mashing with a honey whisk, for example.
In addition, in the Speidel Braumeister there is a fairly large volume of water in the outer area of the malt pipe that is not used for mashing. Depending on the temperature of the mashing water, the temperature in the malt pipe drops below 70 °C after mashing and the beta-amylase can then produce maltose for a certain period of time. The BrewMonk only has a very small "dead volume", so it only needs to be mashed in quickly enough. The BrewTools system's percentage "dead volume" is roughly between the BrewMonk and the Braumeister series, but you can start circulation during mashing so that the target temperature is reached quickly. We have observed that the alcohol content tends to increase from the BrewMonk via the BrewTools to the Braumeister at the same mashing water temperature. However, an exact prediction is not possible because the malt grist can vary slightly depending on the grist mill and the type of manual mashing varies from person to person. In contrast, we have observed a very high level of reproducibility in our 70-liter mash kettle with agitator, and we generally obtain the lowest alcohol contents with this system. A current dark beer with 12 °P has just 2.2 % alcohol by volume, a light bock beer with 17 °P only 4.2 % alcohol by volume.
For this reason, we purchased a BrewTower 140+/180 last year, with the agitator in the upper tank and the wort boiled in the lower tank. Mashing in the upper tank is quite reproducible, but we have ordered two more mash propellers as we feel that the circulation is not sufficient, especially during mashing-in. In our experience, the best results are achieved with a w/w water/malt ratio of 5/1, although we now only brew front wort beers with the BrewTower. The loss of extract is small, but we save time and effort.
However, boiling the wort in the lower container has proven to be problematic. There are 2 heating elements of 5 kW each mounted directly above each other in the brewing kettle, and as the heating power cannot be adjusted with the Craft-Ing control system, boiling over is unavoidable, even if one of the two heating cartridges is disconnected from the mains by a switch. Not only do we lose several liters of wort per boil-over, but the cooling water from the vapour condenser can also get into the brewing kettle and dilute the wort. It would certainly be better to install heating coils, similar to the BrewTools system, which distribute the heating power better. Due to these weaknesses, we have now decided to only use the lower container of the BrewTower to preheat the mash-in water for the second brew; in future, the wort will be boiled in our BrewTools 150 Pro. This also saves us a lot of cleaning work.
We receive a few comments about our isothermal high-temperature mashing process from time to time, but the trend is currently decreasing:
- "That will never work, it's guaranteed to get a blue brew!"
- "It will destroy the beta-amylase!"
- "The brewing process is exhausted, what we're doing today is the optimum!"
- "Alcohol is an important flavor carrier!"
We are always happy to receive comments, because in science, you have to face up to opposition, and opposition should also motivate you to constantly question yourself and continue to develop. Because, "Nobody is perfect!"
We have now carried out some tests with a type of malt (spring barley) that is classified on the HETAIROS website as having medium beta-amylase activity and rather low alpha-amylase activity. We crushed this malt as before and mashed it at 80 °C in a mash pan with an agitator and then mashed it isothermally at 76 °C for 60 minutes. We have not seen any difference in the in situ saccharification, measured in °P, or in the original gravity achieved compared to the Pale Ale malt from Weyermann that we have mainly used up to now. A comparable alcohol content is also obtained in the finished beer.
The question now arises as to how the malts are actually classified in terms of alpha- and beta-amylase activity. Such data is presumably obtained from the congress mashing process, and the so-called final fermentation degree seems to be included in this consideration. However, we look at a malt in isothermal high-temperature mashing from a slightly different angle. For us, it is important that saccharification is complete, i.e. the wort must be visually iodine-normal at the end of mashing.
Another criterion for us is that we obtain the same extract build-up at the end of mashing within the margin of error as in the "high-short mashing process" as well as similar values for free amino nitrogen (FAN). And last but not least, our aim is to achieve the lowest possible alcohol content with a full flavor. From our point of view, it is not only necessary to consider an "isothermal 65 °C test mashing process", which has been known for some time, but also to develop an "isothermal 75 °C test mashing process".
We have activities in our research brewery for the production of gluten-free beers; as part of a funded project, we are working with partners on beers based on a priori gluten-free quinoa. As part of student theses, we are also trying to use commercially available gluten-degrading enzymes to bring the gluten content of beers brewed from barley malt below the detection limit of 10 mg/kg. We have already succeeded in doing this, but we were also confronted with an unexpected problem with these enzymes in the course of the trials.
In two bachelor theses, the aim was to produce alcohol-free gluten-free beers using the isothermal high-temperature mashing process. In only two of six trials did the beers remain at a maximum of 0.5% alcohol by volume, in the other cases the alcohol content rose again after about a week, and in one case we obtained an astonishing alcohol content of 3.5% by volume at 7 °P. As we do not work with diastatic yeasts, our interpretation was that the aroma hops may have been added at too low a temperature, resulting in so-called "hop creep".
However, we became suspicious when the fermentation of a beer produced using the isothermal high-temperature mashing process and fermented with a maltotriose-positive yeast in the presence of a gluten-degrading enzyme simply would not stop. The alcohol content increased every day, and in the end a clear overfermentation was even observed, as is known from diastatic yeasts. In contrast, reference tests without the gluten-degrading enzyme were normal, without overfermentation.
This leads to the conclusion that at least the commercial gluten-degrading enzyme preparations we used from three different manufacturers contain glucoamylases and possibly even alpha- and beta-amylase. This is not declared on the packaging, nor is there any information on this on the manufacturers' websites. It may be that these amylases are not even noticeable in the normal brewing process. This is because the multi-stage infusion mashing process or the high-short mashing process only produces a small amount of unfermentable sugars such as maltotetraose and above, and these beers are also filtered. Today's filter systems in larger breweries are so efficient that beers are effectively bottled sterile-filtered. These beers contain hardly any cleavable sugars and, due to the lack of yeast, any cleavage products are no longer fermented. For the production of alcohol-free or alcohol-reduced gluten-free beers, which are also made from barley malt, we will have to adapt our brewing process in future.