Brandhefe literally “burnt yeast,” is the German name for the brownish residues found on the sides of an emptied fermenting vessel. Usually seen as a ring near the top of the vessel, brandhefe is composed of dried-up yeast, albumen, and hop resins and must be carefully removed after each use of a fermenting vessel. It is a tough, tacky material, and is not always easy to remove. Contrary to its name, it does not consist primarily of yeast, but actually contains proteins and hop resins that make it dark and sticky. The brandhefe is mainly the dried remains of the froth built during the early stages of bottom fermentation, the so-called Kräusen. This froth, which is built up by evolving carbon dioxide, “washes out” undesirable flavors, including some rougher-tasting hop components, from the fermenting young beer. The Kräusen turns dark and eventually brown or even black as the contained hop resins dry out. In the latest phase of primary fermentation, the froth collapses and if not skimmed off sticks to the sides of the vessel, where it can be removed after the vessel is emptied. Traditional lager brewing recipes call for the removal of all dark parts of the Kräusen before racking the beer to a maturation tank, an operation that can only be performed when open fermenters are used in traditional lager beer breweries. In modern cylindroconical fermenters most of the brandhefe will stick to the inner walls or ceiling of the fermenting vessel, but several brewers argue that some of the harsh bitterness in certain modern pilsners may be the result of incomplete removal of brandhefe.