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As part of the module "Introduction to the Chemistry of Brewing" in the Master's degree program in Chemistry at Clausthal University of Technology, a student internship is currently taking place again in our research brewery. In addition to the actual brewing process, students are also learning about other activities that occur in breweries. First of all, we thoroughly cleaned our "Tank Siegfried" with our new CIP system (CIP: Cleaning in Place) and prepared it for the next beer.
We then brewed around 200 liters of Pilsner beer with the "Braumeister 50" and the BrewTools system, whereby, with a few exceptions, we always use the isothermal mashing process at 72 - 76 °C. This means that the malt is mashed at a fairly high temperature. Malt is therefore mashed at a very high temperature, this time at 76 and 78 °C, and our intention is that the beta-amylase is denatured as quickly as possible.
As we have been able to show in several publications, today's barley malts, including Munich malt, which is actually considered to have a low enzyme content, have a more than sufficiently active alpha-amylase, which reliably leads to iodine-normal wort. Ultimately, we only skip the so-called maltose rest, because even the large breweries today generally no longer carry out protein rest. It is thanks to the continuous development of the malting barley community in cooperation with farmers, maltsters and research institutes that today's barley malts are so well pre-dissolved during malting that brewers no longer have to worry about an extensive mashing program.
Only with special malts such as spelt malt, oat malt and others is it necessary to ensure that the mash is enzyme-rich enough. In our experience, spelt malt in particular has a weak alpha-amylase; isothermal mashing > 72 °C with spelt malt or oat malt alone is difficult. We use this mashing process to reduce the alcohol content in a simple way. Most of our full beers with original gravities between 11 and 12 °P have alcohol contents between 3 and 3.5% by volume.
We brewed with a batch (44 kg) consisting of Pilsner malt, Pale Ale malt and Carapils, rounded off with sour wort, achieving a total of 200 liters of wort with 11.8 °P. We finish the mashing itself after 30 minutes, lautering takes place at 72 °C, and the residual saccharification reliably takes place during lautering. Depending on the malt and its milling, the mashing and lautering process takes between 60 and a maximum of 90 minutes. The wort was boiled with the bittering hop "Enigma", and we used Hallertauer Mittelfrüh in the whirlpool at around 80 °C for the aroma. The brew was fermented with Lallemand "Diamond Lager", a Pilsner yeast with good sedimentation and neutral fermentation.
On September 25, we brewed an "Amber Dinkel" and a "Helles", 50 liters each, using the two systems mentioned above. For the first beer, we isothermally mashed a batch consisting of 50% Munich malt and 50% spelt malt and achieved an original gravity of around 10.5 °P; the finished beer would therefore be a draught beer. The mild bitter hopping is done with "Enigma", the aroma hopping with Hallertauer Blanc (Wethop). As the WYeast 3068 (like Weihenstephan W68 or TUM W68) only sediments moderately, this beer will need a little maturing time until the bitterness is harmonious.
We also brewed a so-called Helles, the bill consisted only of Pale Ale malt and Carahell. This type of beer is rather mild in bitterness with a much higher original gravity than a pilsner, and a nice hop aroma is also typical. We used "Enigma" for the bitterness, the whirlpool hopping was done with Hallertauer Blanc (Wethop), the brew is fermented with Lallemand Diamond Lager. The amber spelt is fermented and matured in our "Tank Ulla", the pale ale in "Tank Mathias".
We are currently doing a group project as part of a physical chemistry practical course, and it makes perfect sense to combine brewing with aspects of physical chemistry.
Typical questions in a beer analysis are: What techniques are actually used to determine original gravity and alcohol content in the finished beer, how do you determine bitterness, how do you determine color? What sugars does the yeast utilize, and are there any harmful bacteria in the beer? We always have beers that can be analyzed for such student experiments, but of course the brewing itself should not be neglected.
That's why we brewed 100 liters of beer in our Brewtools 150 system on 3 September with active student support. This involved mashing 25 kg of crushed Pale Ale malt at 76 °C and then subjecting it to a 30-minute rest at 72 °C. Sour beer was added shortly before the end of the rest. In situ, the mash reached a remarkable 16.2 °P, after lautering and secondary wash at 72 °C, 110 liters with 14.2 °P were obtained. For hopping during boiling, we used Northern Brewer in 3 doses (60 minutes, 20 minutes, 10 minutes boiling time), whirlpool hopping was carried out at 83 °C with Hallertauer Blanc Wethop. The finished wort was cooled in a countercurrent process and divided into 2 fermentation vessels. Fermentation took place in both vessels without pressure under a fermentation bell, once with the WYeast "Californian Lager" and once with the ImperialYeast "Pub Ale" at room temperature, approx. 22 °C. The latter is a top-fermented beer. The latter is a top-fermenting yeast that is said to produce very clear beers because it sediments quickly and completely; a so-called diacetyl rest is recommended. Californian Lager is genetically a bottom-fermenting yeast whose optimum temperature is around 20 °C, whereas normal bottom-fermenting yeasts ferment best between 8 and 12 °C. This yeast also sediments very well and produces clear beers in a short time. During the later tasting in the physico-chemical seminar, we will then assess the extent to which two yeasts with similar fermentation behavior influence the taste of the beer in different ways.
With an original gravity of around 14 °P, we expect alcohol levels of around 4% by volume. Both beers should be ready to drink at the beginning of October.