A Brief Study of Beer
Beer is produced by the alcoholic fermentation of water, malt, hops, and yeast. Only barley malt may be used for bottom-fermented beers. For top-fermented varieties, it is possible to use other types of malt, for example wheat, rye, or barley malt. Beer contains carbohydrates, protein, mineral substances, carbon dioxide, alcohol, and is 90 percent water.
The purity law determines that only water, malt, hops, and yeast may be used for the production of beer in Germany. The law was decreed before a meeting of the Estates of Ingolstadt summoned by Duke Wilhelm IV on April 23, 1516 – and is thereby the oldest nearly unchanged valid food law regulation in the world. It still applies in the current Provisional Beer Law and secures the high quality of German beer. The anniversary of the Purity Law is celebrated by the German brewing industry with the “German Beer Day”, which is held each year on April 23rd and includes numerous events, activities, and promotions, which all revolve around the merry subject of beer.
Malt is made from barley, wheat, spelt, or rye. The grains are sprouted in the malt house by adding water and then dried (kilned).
Hops is known as the “soul of beer”. It gives the beer its tart-bitter flavor, improves shelf life, and stabilizes the foam. The largest area for hops cultivation is Hallertau in Bavaria.
Yeast subsequently ferments the wort and transforms the malt sugar in alcohol and carbon dioxide. As a result of bottom-fermented yeasts (saccharomyces carlsbergensis) bottom-fermented beers are created, top-fermented beers are created by using top-fermented yeasts (saccharomyces cerevisiae).
Original gravity designates the percentage of substances dissolved from the malt in the still unfermented wort. These are above all malt sugar, protein, vitamins, and minerals. During fermentation, and promoted by the yeast, this becomes around one-third alcohol and one-third carbon dioxide. A third of the remaining extract is left unfermented. The higher the original gravity content, the stronger the beer. Most beers in Germany lie between eleven and fourteen percent in regard to their original gravity. The alcohol content is then between 4.5 and 5.5 percent. Beer is divided into different beer classes according to the original gravity:
- Common beers (up to 7 % original wort)
- Draft beers (7 to below 11 % original wort)
- Full beers (11 to below 16 % original wort)
- Strong beers (more than 16 % original wort)
The color of the beer is solely determined by the color of the malt. The higher the temperature at which the malt is dried – “kilned” – the darker it will turn. It passes the color on to the beer during the brewing process. Before the introduction of the hot-air kiln in 1807, malt was dried over the open fire. It was hardly possible to influence the temperature, and the malts all turned more or less dark. A more sophisticated malting technique in the early 19th century made it possible to control the malt color and to brew beer that had a lighter color.
Top-fermentation or bottom-fermentation are both brewing methods. It thereby depends on the yeast and the fermentation temperature. The top-fermenting brewing method is the older method, since fermentation is done at higher temperatures (usually between 15 and 20 degrees centigrade), which were more easily achieved before the discovery of the refrigeration machine by Carl von Linde in 1873. The term “top-fermented” is derived from the property of these yeast strains, to rise to the surface of the “green beer”, where the yeast could then be skimmed off and harvested, from the top of the open vessels that were mainly used at the time. Bottom-fermented yeast requires in comparison lower temperatures and settles at the bottom of the fermenting vessel after fermentation. Its implementation was only possible earlier in areas where enough ice could be harvested during the winter, in order to ensure sufficient cooling during the warm season as well. The triumph of bottom-fermented beer began with the discovery of the refrigeration machine. There are still many other specialties today that are brewed with the top-fermenting method, e.g. Kölsch, Alt, Berliner Weisse, or even wheat beer.
The calorie content of beer is moderate. On an average, a liter of beer has a caloric value of 400 kilocalories (1,674 kJ) and can thereby easily compete with other beverages. For easy comparison: fruit juices have an average of 500 kilocalories (2,113 kJ) per liter, a liter of whole milk contains about 660 kilocalories (2,760 kJ), and German red wine can even contain up to 700 kilocalories (2,900 kJ) per liter. So beer does not make you fat and is also not responsible for the legendary “beer belly”.
Source: Deutscher Brauer-Bund e.V. (German Brewers’ Association)