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TU-Clausthal Brewery

May 2022

We brewed experimentally again on May 14 and 26.
 

In a series of experiments, we compared "our" isothermal mashing process, in which malt grist is subjected to a single rest at 72 °C, with a fast "high-short mashing process". Large breweries mash malt at approx. 65 °C and then rest at between 62 and 65 °C for a certain period of time. This is followed by a rest at 72 °C before mashing at 78 °C. Now we were interested in whether this could be done much faster without compromising the quality of the beer. In 3 trials each, we mashed 2 kg of Pale Ale malt in 12 liters of water in the "Braumeister 10" and then subjected it once to an isothermal rest at 72 °C and once to a shortened, more or less classic mashing process. In both mashing processes, mashing and lautering took less than 60 minutes in this small system, and we also dispensed with the so-called "retailing", i.e. we only used the front wort.
We obtained around 10 liters of wort in each of the two test series. The wort from both test series was collected, boiled and hopped separately, and the beers were then fermented with the maltotriose-negative "Mangrove Jack's M15". With almost identical original wort in both mashing processes, the beer brewed using the isothermal process at 72 °C achieved an alcohol content almost 1% lower by volume. The laboratory analyses of the various sugars, viscosity and free amino nitrogen confirm earlier results. With the small "Braumeister 10" system, the mashing and lautering process can be completed in less than 60 minutes, and if the heating time up to boiling is taken into account and the wort is boiled for an hour, the entire brewing process from mashing in to striking out is completed after 2 1/2 hours. The extent to which this time advantage can be transferred to the systems in large breweries cannot yet be assessed with certainty from these laboratory tests. However, such a process is now being used at the Zellerfeld Brewing Academy, and the entire brewing process only takes 3 hours on the 2-device system there with a volume of 300 liters. So it would be no problem to brew 900 liters of beer there in one day - if only it weren't for the cleaning ....
 

In the fall of 2021, before "Corona" abruptly interrupted our activities again for a good 4 months, we experimented with producing low-alcohol IPAs. Using the isothermal mashing process, we can produce wort that has an alcohol content of just 3.5% by volume at an original gravity of 12 °P with conventional yeasts. IPAs are characterized by a fruity aroma, which is achieved by subjecting the fermenting wort to a cold hopping process. During this process, many aromas are extracted from the hops, and if the yeast has beta-glucosidase, glycosidic bonds between glucose and aroma components are cleaved, with the aroma compounds then released deepening the fruity aroma. Unfortunately, ordinary hop pellets contain glucoamylases, alpha- and beta-amylase, i.e. during fermentation, the hop enzymes break down higher sugars (dextrins) into fermentable sugars and ferment them with the yeast.
As a result, alcohol contents of 7% by volume are quickly achieved at moderate original wort temperatures of around 14 °P, and this fermentation behavior can hardly be distinguished from diastatic yeasts, which also have starch-splitting enzymes. We have had ambivalent experiences with WetHop, pasteurized fresh hops. Some varieties no longer have any enzymatic activity, while others break down higher sugars into fermentable ones during cold hopping. WetHop also contains isomerized alpha acids, which intensify the bitterness during dry hopping. In this way, high alcohol contents are achieved and the pre-isomerized alpha acids can lead to a very bitter beer. However, the aroma profile of wet-hopped IPAs is quite convincing, both in terms of aroma and taste, but the brewing process must be adapted. Depending on the duration of the dry hopping, bitter hopping during the boil can probably be dispensed with and IPAs with 3-4% alcohol by volume should be feasible. However, the existing recipes need to be adapted for this.

On the way to low-alcohol IPA's, we have therefore also tried out the new product from BarthHaas, "Spectrum". This is an aroma hop extract that is expressly suitable for dry hopping and is also free from enzymatic activity. The previous trials in May 2022 have not yet resulted in a clear evaluation, which is why we carried out a series of trials this time in which we varied the yeasts. For this purpose, a wort was produced from Pilsner malt, Pale Ale malt, Carapils and sour malt using the isothermal mashing process at 72 °C, which was adjusted to approx. 15 IBU with the bittering hop "Herkules". The original gravity achieved was around 12 °P. This batch was divided into 5 small fermentation vessels and 10 g of "Spectrum" in the "Citra" variant was added to each of them. The yeasts used were: Lærdal Kveik, Imperial Yeast Kveiking, Opshaug Kveik, Voss Kveik and, in a mixed fermentation, BRY-97/Nottingham Ale. These yeasts have different amounts of beta-glucosidase, so we will get a first insight into which of these yeasts emphasizes the fruit aroma of Citra. Citra is referred to as the "fruit salad" of hops, and with classically brewed IPA's we also have a good comparison of what flavor profile "Spectrum" Citra provides.

At the beginning of May, we brewed - more or less - experimentally and tried out new approaches.
 

  • Single beer:
    Single beers have an original gravity of 1.5 to 6.9 °P and are rarely offered commercially. They taste a little watery and lack the full-bodied flavor typical of beer. Nevertheless, they are interesting because at an original gravity of 2.5 °P, brewed using the isothermal mashing process, they achieve an alcohol content of only 0.5% by volume even with standard yeasts and are considered "alcohol-free" by law.
    The background to this is that a person without a lack of alcohol dehydrogenase breaks down the alcohol absorbed directly again, even if such beers are consumed extensively, so there is no accumulation. Our own tests using an alco-tester have confirmed this assumption, but caution is advised for people who suffer from an alcohol allergy.
    These beers are easy to brew, they require neither dealcoholization nor the use of special yeasts. This time we brewed with Munich malt, Pale Ale malt, Carahell and Sauergut in Brew Monk 50 and achieved an original gravity of around 3 °P. We tried to compensate for the lack of malt body (full body) by using two different aroma hops (Waiiti, Mandarina Bavaria) in the whirlpool. In addition, the new product "Spectrum" from Bart Haas was used in the dry hopping, in the "Citra" variant. This is an aroma hop extract that is supposed to deliver equivalent results to classic dry hopping, but without the dreaded hop creep due to starch-splitting enzymes in the hops. For fermentation, we used the "Windsor Ale" from Lallemand, which cannot ferment maltotriose and higher sugars, so we expect no more than 0.5% alcohol by volume. It remains to be seen whether the pH value after primary fermentation is low enough to precipitate out the undesirable hop resins, which would otherwise cause an unpleasant bitterness. If necessary, we would have to treat with biological lactic acid until the taste is harmonious. You can also do research in the field of beer ....

     
  • "Empire Ale"
    Like Lallemand's "Windsor Ale", Mangrove Jack's "Empire Ale" is a so-called maltotriose-negative yeast, i.e. it only ferments fructose, glucose, sucrose and maltose, but not the higher sugars that give a beer its full-bodied flavor. For details on the yeasts, please refer to the manufacturers. In our experience to date, these yeasts produce malty, "sweet" beers that are well received. Using Pale Ale malt as a base and Carahell and Carapils to round off the color and flavor, we mashed once isothermally at 72 °C using sour mash and once using a new ultra-high-short mashing process. We used our Braumeister 50 from Speidel and, apart from the different mashing process, we kept all the steps the same for both brews. The bitterness was adjusted to approx. 30 IBU with "Herkules", the whirlpool hopping was carried out at 85 °C with "Mandarina Bavaria". For the dry hopping, we added the new product "Spectrum" from Bart Haas in the Citra variant at the start of fermentation. Fermentation took place with Mangrove Jack's M15 - Empire Ale and was completed after one day at 22 °C. Both beers are currently being cold matured at 2 °C in a ZKG.

     
  • Ebbegarden Kveik
    We have already made many beers with Norwegian Kveiks and this time we brewed a batch with the "Ebbegarden Kveik" from Escarpment Labs. The manufacturer writes:
    "Ebbegarden Kveik Blend
    Works well with hops and accentuates their mango and guava aromas.
    Hailing from Stordal in Norway, Ebbegarden Kveik yeast is your IPA's secret ingredient to enhance tropical fruit aromas from your hops."

    In other places it is implicitly mentioned that this yeast blend has beta-glucosidase, which emphasizes the hop character. This time we opted for a NEIPA, which in simple terms is an IPA without the inherent bitterness of an IPA. The bill consisted of Pale Ale malt and Carapils, brewed in parallel using the isothermal mashing process at 72 °C in the "Braumeister 50" and in the "Brewtools 150 Pro", so we produced a total of 200 liters. A late addition of "Herkules" hops resulted in a barely perceptible bitterness of 10 IBU, while the new "Spectrum" product from Bart Haas in the Citra variant was used for dry hopping. The Citra aroma hops are described as a "fruit salad of hops", with aromas of lime, mango, tropical fruit, passion fruit, lychee, grapefruit, gooseberry, peach and red berries. With an original gravity of around 12 °P, we expect around 3.5% alcohol by volume. Towards the middle/end of June we will see whether the brewing has been successful, until then the beer will slowly mature in "Tank Siegfried".