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The research brewery at the Institute of Electrochemistry at Clausthal University of Technology focuses on the hitherto little-known mashing process at constant temperatures of more than 72 °C, i.e. the isothermal high-temperature mashing process. In a conventional brewing process, many breweries today use a more or less predetermined temperature program for mashing.
Crushed malt is mashed at approx. 55 °C, especially in small breweries, and then subjected to a “protein rest” at 52 - 55 °C, during which the proteins not yet dissolved in the malting process are further broken down by enzymes present in the malt for 15 - 20 minutes. This produces amino acids, which the yeast needs for later fermentation, as well as proteins that stabilize the foam in beer.
Today's malts, which are further developed from year to year through breeding, are already dissolved so well during the malting process in malt houses that this protein rest is no longer necessary, and many large breweries skip the protein rest and mash directly at approx. 65 °C. In this area, beta-amylase (from the malt) is active, releasing glucose, maltose, and maltotriose, sugars that can be fermented by most yeasts, from the starch. At approx. 72 °C, the alpha-amylase from the malt again shows high activity, releasing glucose, maltose, and maltotriose from the starch in the malt, but in smaller quantities, as well as higher non-fermentable sugars up to the so-called dextrins. This process is known as the high-short mashing process.
The result of this mashing process is that a typical Pilsner beer with an average original gravity of 11.5 °P (i.e. 115 g of dissolved substances in one kilogram of unfermented wort) contains around 5% alcohol by volume.
We asked ourselves what would happen if the rest at 65 °C were also omitted and the malt were mashed in such a way that a constant temperature of 72 °C was maintained during mashing, because beta-amylase is weakened at this temperature. These experiments showed that the amount of fermentable sugars is reduced, the amount of non-fermentable sugars is increased, and a Pilsner beer with an original gravity of 11.5 °P achieved with this method, which is highly dependent on the malt, has an alcohol content of between 2.5 and 4% vol.
If dark malts such as “Munich malt” are used in combination with dark caramel malts, beers with an alcohol content of around 2.5% vol. are obtained at 11.5 °P. This little-known mashing process also offers potential in combination with maltotriose- or maltose-negative yeasts, which can be used to produce low-alcohol and even non-alcoholic beers. Maltotriose-negative yeasts such as Windsor from Lallemand Brewing or Empire Ale from Mangrove Jack's have been commercially available for some time, but now the first commercial maltose-negative yeasts are also available. We like to use LoNa from Lallemand for the production of non-alcoholic pale ale beers, as this yeast also metabolizes the wort aromas well.
In a completed project, we were able to show that a special variety of quinoa grown by a farmer in the Vorharz region can be used to produce tasty and completely gluten-free pale ale beers.