Bottom fermented yeast

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Bottom-fermenting yeast ( Saccharomyces uvarum or Saccharomyces carlsbergensis , scientifically correct Saccharomyces pastorianus ) is a hybrid of the classic brewer's yeast ( Saccharomyces cerevisiae ) and the yeast type Saccharomyces eubayanus . When brewing decreases after fermentation the bottom yeast hence the name on the bottom of the fermentation vessel. The yeast set is also known in technical terms as "Druse" or " Geläger ". Today, pure yeasts are mainly used.

In contrast to top-fermenting yeast, bottom-fermenting yeast requires a lower temperature between 4 and 9 ° C for fermentation. Because of this, fewer spontaneous infections can multiply; In addition, bottom-fermented brewing requires a longer fermentation and storage time. Typical bottom-fermented beers are: Pils , Export , Märzen , Lager .

history

It is not known when and where the first bottom-fermented brewing took place. The oldest possible references to bottom-fermented brewing come from the pen of a Nuremberg town clerk, which can be interpreted to mean that the red beer was brewed with bottom- fermentation as early as the beginning of the 14th century .

In a brewing regulation of the city of Nabburg in the Upper Palatinate from 1474 it is determined that in addition to top-fermented beer, bottom-fermented beer should also be brewed as a reserve for the summer. In his book about beer brewing, published in 1581 , Christoph Kobrer , who works as a customs officer and schoolmaster in Kallmünz in Upper Palatinate , distinguishes three different types of fermentation. He assigns the first to the production of top-fermented barley beer and the second to the production of top-fermented wheat beer in Bavaria, and the third type of fermentation for the production of bottom-fermented beer to the Upper Palatinate.

Before Carl von Linde developed the improved refrigeration technology in the 1870s, bottom-fermented brewing relied on naturally low temperatures. This also explains why the bottom-fermented brewing method has a long tradition in areas with severe winters. Regions with rock cellars such as Bohemia , Franconia or the Upper Palatinate also had an advantage . Elsewhere in winter, ice blocks were cut out of frozen water and stored in caves and deep cellars ( ice cellars ). This was then used to cool the fermentation vats when the ambient temperatures were already too high for brewing.

Pure culture yeasts

For the pure yeast used in beer production today, it is necessary to also examine the yeast biologically. For this purpose, the breweries have operational controllers who are trained either at the universities ( HS Weihenstephan , VLB -Berlin, TH OWL ) or master brewer schools. In order to rule out any contamination, samples are also sent to the respective universities, master brewing schools or other laboratories.

In order to control the yeast, samples are taken, either immediately examined under the microscope or enriched with nutrient media and examined visually (with the "naked eye") or under the microscope due to a visible change in the medium. This task is incumbent on the biological plant control, which is also important for many other controls (not only with regard to yeast) in the brewery. In the 1960s and 1970s there was a surge in the development of all operational controls, not just biological ones. This led to the high quality of bottom-fermented beers today. A nutrient medium for the detection of beer spoilage that was just emerging at the time was the Japanese Nakagawa medium, which was also investigated in Germany by Klaus Grunenberg and, for example, T. was modified.

Individual evidence

  1. ↑ Gene analysis: the forefather of Pils yeast comes from South America . In: Spiegel Online , August 23, 2011, accessed October 5, 2014.
    Jian Bing, Pei-Jie Han, Wan-Qiu Liu, Qi-Ming Wang, Feng-Yan Bai: Evidence for a Far East Asian origin of lager beer yeast . Current Biology 24, Issue 10, May 19, 2014, pp. R380 – R381, doi : 10.1016 / j.cub.2014.04.031 .
  2. ↑ Jochen Sprotte: From 1303/1305 to 2005. 700 years of Nuremberg beer. In the yearbook of the Society for the History of Brewing 2005, Institut für Gärungsgewerbe Berlin, pages 87-131.
  3. ^ A b Franz Meußdoerffer , Martin Zarnkow: The beer: A story of hops and malt . CHBeck Verlag, 2014, ISBN 3406666671 , p. 86
  4. ^ "Brewing Science" Volume 28 / Issue 6 WP Hsu, JA Taparowsky and MW Brenner; A. Nakagawa: "A Simple Method for the Detection of Beer-Sarcina", Bull.Brew.Sci (Tokyo) 10 7-10, 1964; K. Grunenberg: "Fast determination of beer spoilage", Brauwelt 115, 46-48, 1975