Concept
Lager (ˈlɑːgər) is a type of beer which has been brewed and conditioned at low temperature. Lagers can be pale, amber, or dark. Pale lager is the most widely consumed and commercially available style of beer. The term "lager" comes from the German for "storage", as the beer was stored before drinking, traditionally in the same cool caves in which it was fermented. As well as maturation in cold storage, most lagers are distinguished by the use of Saccharomyces pastorianus, a "bottom-fermenting" yeast that ferments at relatively cold temperatures. Until the 19th century, the German word Lagerbier (de) referred to all types of bottom-fermented, cool-conditioned beer in normal strengths. In Germany today, it mainly refers to beers from southern Germany, either "Helles" (pale) or "Dunkel" (dark). Pilsner, a more heavily hopped pale lager, is most often known as "Pilsner", "Pilsener", or "Pils". Other lagers are Bock, Märzen, and Schwarzbier. In the United Kingdom, the term commonly refers to pale lagers derived from the Pilsner style. While cold storage of beer, "lagering", in caves for example, was a common practice throughout the medieval period, bottom-fermenting yeast seems to have emerged from a hybridization in the early fifteenth century. In 2011, a team of researchers claimed to have discovered that Saccharomyces eubayanus is responsible for creating the hybrid yeast used to make lager. Based on the numbers of breweries, lager brewing became the main form of brewing in the Kingdom of Bohemia between 1860 and 1870, as shown in the following table: In the 19th century, before the advent of refrigeration, German brewers would dig cellars for lagering and fill them with ice from nearby lakes and rivers, which would cool the beer during the summer months. To further protect the cellars from the summer heat, they would plant chestnut trees, which have spreading, dense canopies but shallow roots which would not intrude on the caverns. The practice of serving beer at these sites evolved into the modern beer garden.
