April 2024

On 30 April, we brewed around 200 liters of "Amber Lager", a bottom-fermented beer characterized by a mild bitterness and subtle malt aromas. The batch therefore consisted of 50% pale ale malt and 50% Munich malt, mashed in our BrewTower 140+ at 76 °C for 30 minutes or 60 minutes for the second brewing process.
In the standard version of the BrewTower, the agitator consists of two agitator paddles, the circulation from the heated area below the lauter floor to the area where mashing takes place is realized with an external pump. In the past, we have observed that the circulation for mashing in above the gelatinization temperature, as is the case with isothermal high-temperature mashing, was noticeably too low and many lumps were formed that only broke down very slowly. Reaching into an agitator with a manual paddle to break up these lumps is not really recommended.
To solve this problem, we therefore upgraded the agitator with two additional agitator paddles and replaced the circulation pump with one with a much higher flow rate. These two very easy-to-implement measures meant that any lumps that formed during mashing were completely disintegrated after a few minutes, allowing saccharification to proceed smoothly.
Once mashing was complete, the wort was lautered via the lauter tun directly into our BrewTools 150 Pro, in which the wort was boiled with sour beer and Hallertauer Magnum for 60 minutes. As this is a front wort beer, no secondary additions were made during lautering. During this boiling time, the BrewTower was mashed a second time, and the longer mashing time was solely due to the fact that the BrewTools had just been filled with the first brew.
Aroma hopping was carried out in the whirlpool with Hallertau Mittelfrüh and Slovenian Styrian Golding. While the Mittelfrüh results in more classic hop aromas, the Styrian Golding also produces aromas of lemon and pine in the beer. Both brews are fermented together unpressurized in our Siegfried tank with Lallemand Brewing "Diamond". This brewer's yeast is recommended for many bottom-fermented beers and we have the best experience with it for the production of pilsner beers or bock beers. Beers fermented with this yeast clarify well and the yeast seems to precipitate lees from malt and hops very well. This also means that the matured beers can be filtered comparatively easily through a candle filter, whereas the candle tends to clog up quickly in the case of dust yeast and has to be rinsed more frequently, with unavoidable losses.
We have set the fermentation temperature to 12 °C, and we expect fermentation to be complete after a week at the latest. Experience has shown that with this dry yeast sprinkled directly onto the wort, it takes a good two days before fermentation activity can be detected. With an original gravity of around 11.5 °P, we expect an alcohol content of no more than 2.5 % vol. The beer should be ready to drink in around 6 weeks after filtration. We will report on our experiences with filtering beers in a future article. Cartridge filters with the smallest pore sizes of 450 nm can be implemented for microbreweries without too much financial or technical effort, and filtration makes the beers more reproducible in production. However, we had to go through a certain learning curve, especially with regard to the storage of such a filter candle.

The day of German beer
On April 23, 1516, one of the oldest laws on food quality was passed in Ingolstadt, which is now known as the "Purity Law". Ultimately, the princes decreed that only barley, hops and water should be used to brew beer in future. Yeast, which strongly influences the character of a beer, was not yet known as such at the time; people simply did not know what this "stuff" was, without which neither bread would rise nor beer would ferment. As wheat is a demanding crop compared to barley in terms of soil quality and the harvests and soils were rather poor due to the Little Ice Age at the time, wheat was used for bread and barley for beer. Malt was certainly also used in brewing back then, as barley alone is far too weak in enzymes, but the processes involved in malting were unknown and enzymes were certainly not yet known.
 

On April 23, 2024, we brewed an alcohol-free beer with a maximum of 0.5% alcohol by volume for an upcoming event at Clausthal University of Technology using our isothermal high-temperature mashing process. A 50/50 blend of Pale Ale malt and Munich malt was mashed in our 50/70 liter mash tun with agitator at 82 °C, and mashing took no more than one minute. During this time, the temperature dropped to 78 °C, and this temperature was kept constant for 60 minutes. After around 30 minutes, the mash was already visually iodine-normal with an in situ extract of around 12 °P, which rose only slightly to 12.4 °P after a further 30 minutes. It is therefore by no means the case that the alpha-amylase is quickly denatured at 78 °C. On the contrary, the malt is saccharified without any problems and the in situ extract build-up corresponds to that of the industrial high-short mashing process with the same duration, but with a different sugar distribution.
After lautering, this wort was diluted with water and adjusted to an original gravity of around 7 °P. This original gravity is the upper limit so that maltose-negative yeasts do not produce more than 0.5% alcohol by volume. The wort was boiled in the presence of Sauergut and Hallertau Magnum, Rottenburg aroma hops were added in the whirlpool. When fermenting with maltose-negative yeasts, the addition of Sauergut is obligatory, as otherwise there is no sufficient pH drop, which is necessary for the precipitation of undesirable hop components on the one hand and guarantees microbiological safety with a pH value of 4.5 and below on the other. If a sufficient amount of souring agent is omitted, the result is an undrinkably bitter beer, and the question of microbiological stability does not even arise.
After boiling, the original gravity was adjusted back to 7 °P and fermentation took place after cooling in a previously carefully pasteurized container made of food-safe stainless steel with Saccharomycodes Ludwigii, also known simply as "Ludwig yeast". This yeast ferments fructose, glucose and sucrose, but not maltose and higher homologs.
On April 29, the beer was finally fermented with the expected alcohol content of 0.5% vol, which allows the beer to be labeled "non-alcoholic" by law. Although this beer contains very small amounts of alcohol, these are physiologically harmless, provided there is no alcohol allergy or a lack of alcohol dehydrogenase, as a healthy adult can break down between 0.085 and 0.1 g of alcohol per hour and kilogram of body weight. One liter of such a beer contains around 4 g of alcohol, and you have to drink 2 liters of it per hour for the alcohol intake to exceed the rate of physiological degradation. The feasibility of such a project should be tested by each individual in a self-experiment. As fruit juices can also contain alcohol (up to 0.5 % vol. for apple juice, even up to 1 % vol. for grape juice), the legislator has set this limit.
When brewing with maltose-negative yeasts, meticulous care must be taken to ensure that no other yeasts get into the wort. In principle, a single cell of a normal brewer's yeast in the wort would be enough for fermentation to continue, imperceptibly slowly at first, but then faster and faster. To prevent this, such a beer must either be sterile-filtered or pasteurized. We have decided to gently pasteurize the unpressurized end-fermented beer in closed 20-litre barrels at around 63 °C and subject it to forced carbonation after cooling. In the final step, it is then filtered through a candle filter with a pore size of 450 nm, which effectively removes all yeast cells, should any creep in at any point.
Last autumn/winter, we produced an alcohol-free beer in this way using a different maltose-negative yeast, and there was no unplanned pressure build-up in the barrels or bottles. The last remaining bottles are still inconspicuous today. However, this presupposes that meticulous attention is paid to cleanliness when filling or decanting. For this purpose, we thoroughly sterilize all hoses, the manual counter-pressure filling system and all tap heads with wet steam, and the bottles are filled with beer straight from the cleaning process, just like in a large brewery. So far, this procedure has proved successful, and only in the case of a bottle of such a non-alcoholic beer as a guest gift would we carry out an additional bottle pasteurization to be on the safe side - you never know!

We have extracted harvest yeast from the green beer and store it in a closed container at 2 °C in a cold chamber. In the next few weeks, we want to brew another "Ludwigsbier" with this harvest yeast. We also want to find out whether the alcohol content stops again at 0.5% vol. or whether there are any maltotrio-positive yeasts from the brewing air in the harvest yeast. Furthermore, pasteurization is to be optimized in future trials. For further experiments on the production of non-alcoholic beers, we will use the Cyberlindnera Misumaiensis and a Saccharomyces Jurei, which our colleagues at the Center for Brewing and Food Quality (BLQ) at the Technical University of Munich in Freising-Weihenstephan have kindly made available. The former ferments only glucose and fructose and almost produces the taste of a Pilsner beer, while the latter produces the typical aromas of a wheat beer. Although the Jurei yeasts are maltose-negative, they do begin to ferment maltose and higher after a while, which is why sterile filtration and/or pasteurization are mandatory.